This manual must only be used by a qualied heating installer/service technician. BEFORE installing, read
all instructions in this manual and all other information shipped with the boiler. Perform steps in the order
given. Failure to comply could result in severe personal injury, death or substantial property damage.
•Installation
•Startup
•Maintenance
•Parts
Boiler Manual
Part number 550-142-330/0421
Series4
Oil-FiredSteamBoilers
Part number 550-142-330/0421
2
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
HOMEOWNERandSERVICETECHNICIAN—readandfollowcompletely.
The following defined terms are used throughout this manual to bring attention to the presence of hazards
of various risk levels or to important information concerning the life of the product.
Indicates presence of hazards that will cause severe personal injury, death or
substantial property damage.
Indicates presence of hazards that can cause severe personal injury, death or
substantial property damage.
Indicates presence of hazards that will or can cause minor personal injury or
property damage.
Indicates special instructions on installation, operation or maintenance that
are important but not related to personal injury or property damage.
When calling or writing about the boiler
Please have boiler model number and series from boiler rating label and Consumer Protection (CP) number(s)
from boiler jacket, burner and controls. On page 35 of this manual is space to list CP number(s).
Homeowner —
Read and follow all information on pages 1 through 7 ONLY.
Service technician —
Read and follow ALL information in the entire manual.
Failure to follow all instructions in proper order can cause severe personal injury, death or
substantial property damage.
Using this manual
Hazard definitions
Packaged boilers: Available only in sizes 3 through 6, are factory assembled, completed with block, collector
hood, jacket, controls and trim (damper included, shipped loose inside boiler shipping
carton). Burner is ordered and shipped separately
Semi-packaged boilers: Available only in sizes 3 through 6, are shipped with block assembled with collector hood
and jacket installed. Control, trim, damper and burner are ordered and shipped separately
for field assembly.
Knocked-down boilers: Available in sizes 3 through 9, are shipped with block assembled only. All other components
are ordered and shipped separately for field assembly.
Part number 550-142-330/0421
3
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
HOMEOWNERandSERVICETECHNICIAN—readandfollowcompletely.
Contents
Usingthismanual.....................2
When calling or writing about the boiler . . . . . . . .2
Packaged, Semi-packaged and Knocked-down boilers 2
Hazarddenitions.....................2
Contents..........................3
Readthisrst!......................4
Routinemaintenanceschedule..............5
Beginning each heating season . . . . . . . . . . . .5
Daily during heating season . . . . . . . . . . . . . .5
Weekly during heating season . . . . . . . . . . . . .5
Periodically during heating season . . . . . . . . . .5
End of heating season . . . . . . . . . . . . . . . . .5
Boiler shutdown . . . . . . . . . . . . . . . . . . . .5
Pleasereadthisbeforeproceeding...........6
Start-Up . . . . . . . . . . . . . . . . . . . . . . . .6
Check Daily . . . . . . . . . . . . . . . . . . . . . . .6
Check Monthly . . . . . . . . . . . . . . . . . . . . .6
Check Periodically . . . . . . . . . . . . . . . . . . .6
Troubleshooting. . . . . . . . . . . . . . . . . . . . . .7
Beforeinstallingboiler..................8
Installations must comply with . . . . . . . . . . . . .8
Before selecting boiler location . . . . . . . . . . . .8
Provide clearances around boiler (see Figure 2) . . .8
Provide air for combustion and ventilation . . . . . .9
Lay a foundation, if needed . . . . . . . . . . . . . .9
Air contamination . . . . . . . . . . . . . . . . . . . 10
Operation.........................11
SGO with float-type low water cutoff . . . . . . . . 11
SGO with probe-type low water cutoff. . . . . . . . 12
Installboiler-Packaged boilers only...........13
Place boiler . . . . . . . . . . . . . . . . . . . . . .13
Perform hydrostatic pressure test . . . . . . . . . .13
Installboiler-Semi-packaged & Knocked-down boilers14
Place boiler . . . . . . . . . . . . . . . . . . . . . .14
Tankless heater, if used. . . . . . . . . . . . . . . . 14
Perform hydrostatic pressure test . . . . . . . . . .16
Install jacket (Knocked-down boilers only) . . . . . 16
Install boiler controls . . . . . . . . . . . . . . . . .16
Installburnerandchimney—allboilers . . . . . . .18
Install burner (also refer to instructions
packed with burner) . . . . . . . . . . . . . . . . . 18
General chimney requirements. . . . . . . . . . . . 18
Connectbreeching...................18
Connect breeching . . . . . . . . . . . . . . . . . .18
Connectsteampiping. . . . . . . . . . . . . . . . . .20
General piping information . . . . . . . . . . . . . . 20
Install piping . . . . . . . . . . . . . . . . . . . . . 20
To connect SGO boilers to indirect-fired
water heaters . . . . . . . . . . . . . . . . . . . . .20
Optional reservoir piping . . . . . . . . . . . . . . .23
Connecttanklessheaterpiping . . . . . . . . . . . .24
To pipe tankless heater. . . . . . . . . . . . . . . . 24
Connectwiring—generalinformation........26
General wiring requirements . . . . . . . . . . . . .26
Thermostat wiring . . . . . . . . . . . . . . . . . . 26
Junction box (furnished) . . . . . . . . . . . . . . .26
Burner wiring . . . . . . . . . . . . . . . . . . . . .26
High temperature limit . . . . . . . . . . . . . . . . 26
Blocked vent shutoff switch . . . . . . . . . . . . . 27
Connectwiring(Float-typeLWCO)...........28
Blocked vent shutoff switch (BVSS), when required 29
Connectwiring(Probe-typeLWCO)..........30
Blocked vent shutoff switch (BVSS), when required 31
OVD Vent damper wiring . . . . . . . . . . . . . . .32
Connectoilpiping. . . . . . . . . . . . . . . . . . . .32
General oil piping requirements . . . . . . . . . . .32
Oil piping connection at burner . . . . . . . . . . . 32
Startup..........................33
Steam water treatment . . . . . . . . . . . . . . . . 33
Fill the system . . . . . . . . . . . . . . . . . . . . 34
Tips for steam systems. . . . . . . . . . . . . . . . 34
Skim steam boiler. . . . . . . . . . . . . . . . . . . 34
To place in operation . . . . . . . . . . . . . . . . .34
Checkoutprocedure . . . . . . . . . . . . . . . . . .35
Check off “Steps” as completed . . . . . . . . . .35
Installationandservicecerticate. . . . . . . . . . .35
Annualservicechecklist. . . . . . . . . . . . . . . .36
Serviceandmaintenance. . . . . . . . . . . . . . . .37
General description of control operation . . . . . . 37
Burner adjustments . . . . . . . . . . . . . . . . . 37
Controls requiring annual service . . . . . . . . . . 37
Cleaning boiler flue ways. . . . . . . . . . . . . . . 38
Inspect . . . . . . . . . . . . . . . . . . . . . . . . .38
Reported problems . . . . . . . . . . . . . . . . . . 38
Boiler area . . . . . . . . . . . . . . . . . . . . . . 38
Piping . . . . . . . . . . . . . . . . . . . . . . . . .38
Service . . . . . . . . . . . . . . . . . . . . . . . . .39
Check/test . . . . . . . . . . . . . . . . . . . . . . .39
Check monthly . . . . . . . . . . . . . . . . . . . . . 39
Boiler and system piping . . . . . . . . . . . . . . . 40
Review with owner. . . . . . . . . . . . . . . . . . . 40
Boiler relief valve. . . . . . . . . . . . . . . . . . . . 40
Replacementparts...................41
Dimensions.......................46
Ratings..........................47
Handlingceramicberandberglassmaterials...48
Part number 550-142-330/0421
4
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
HOMEOWNERandSERVICETECHNICIAN—readandfollowcompletely.
Tips for water systems —
•Check boiler and system piping for leaks. Continual makeup
water will reduce boiler life. Minerals can build up in sec-
tions, reducing heat transfer and causing cast iron to over-
heat, resulting in section failure.
Failure to maintain recommended pH and repair
leaks can cause section iron corrosion, leading to
section failure and leaks. Do not use petroleum-
based sealing or stop-leak compounds in boiler
systems. Damage to system components can result,
causing property damage.
•Boiler water pH 7.0 to 8.5 is recommended. For pH condi-
tions outside 7.0 to 8.5 range or unusually hard water areas
(above 7 grains hardness), consult local water treatment
company.
•When using antifreeze:
❏ Use antifreeze especially made for hydronic systems.
Inhibited propylene glycol is recommended.
Do not use automotive, ethylene glycol, undiluted
or petroleum-based antifreeze. Severe personal
injury, death or substantial property damage can
result.
❏ 50% solution provides protection to about –30°F.
❏ Local codes may require back-flow preventer or actual
disconnect from city water supply.
❏ Determine quantity according to system water content.
Boiler water content is listed on back cover of Boiler
Manual.
❏ Percent of solution will affect sizing of heat distribution
units, circulator and expansion tank.
❏ Follow antifreeze manufacturer’s instructions.
❏ Do not add cold water to hot boiler. Thermal shock can
cause sections to crack.
Saltwater Damage — The exposure of boiler components to
saltwater can have both immediate and long-term effects. While
the immediate effects of saltwater damage are similar to those
of freshwater (shorting out of electrical components, washing
out of critical lubricants, etc.), the salt and other contaminants
left behind can lead to longer term issues after the water is gone
due to the conductive and corrosive nature of the salt residue.
Therefore, Weil-McLain equipment contaminated with saltwater
or polluted water will no longer be covered under warranty and
should be replaced.
Electrical Damage — If any electricalcomponent or wir-
ing
came into contact with water, or was suspected to have
come into contact with water, replace the boiler with a new
Weil-McLain boiler.
Frozen Water Damage Hazard
Residences or buildings that are unattended in severely cold
weather, boiler system components failures, power outages, or
other electrical system failures could result in frozen plumbing
and water damage in a matter of hours. For your protection,
take preventative actions such as having a security system
installed that operates during power outages, senses low
temperature, and initiates an effective action. Consult with
your boiler contractor or a home security agency.
Homeowner —
•For homeowner or person responsible for simple
start-up and routine maintenance of the system.
Instructions on 1 through page 7 must be followed to
assure proper operation of your boiler. See page 7 for
lists common problems and possible corrections. In
addition, it is your responsibility to:
•Have boiler and burner installed by a qualified
installer.
•Have boiler and burner serviced annually by a
qualified service technician.
•Review and understand start-up and routine
maintenance procedures with qualified service
technician.
•Perform routine maintenance as described on
page 5 and
Service technician —
•For a qualified service technician who has the nec-
essary equipment to check the boiler and system
performance, and is responsible for start-up and
service of boiler and system.
•All instructions in this manual must be followed to
assure proper operation of this boiler.
•Annually service boiler and burner to assure proper
operation. See page 36 for service record.
•Review and explain start-up and routine mainte-
nance procedures with homeowner.
Follow instructions below to prevent se-
vere personal injury, death or substantial
property damage:
•To avoid electric shock, disconnect electrical supply
to burner service switch and additional external
switches before performing service.
•To avoid severe burns, allow boiler to cool before
performing service.
•Do not block flow of combustion or ventilation air
to boiler.
•Boiler must be connected to a flue with sufficient
draft at all times to assure proper operation.
Do not use this boiler if any part has been under water.
Electrical and mechanical failures may cause electric
shock and fire risks. Immediately call a qualified ser-
vice technician to inspect chimney or vent, boiler and
burner. Have the boiler flue ways cleaned and have the
following replaced:
•all electrical and mechanical controls
•electrical wiring
•oil burner and controls
•insulation and chamber lining
Read this first!
Part number 550-142-330/0421
5
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
HOMEOWNERandSERVICETECHNICIAN—readandfollowcompletely.
Routine maintenance schedule
Beginning
each heating season
❏ Call a qualified service technician to perform annual service.
Daily
during heating season
❏ Check that boiler area is free from combustible materials, gasoline
and other flammable vapors and liquids.
Weekly
during heating season
❏ Check for and remove any obstructions to flow of combustion or
ventilation air to boiler.
❏ Check that breeching is attached between boiler and chimney. If
breeching is loose or damaged, immediately turn off switch on
boiler and call service technician to repair.
❏ Check for oil leaks in oil piping and around burner. If found, im-
mediately call qualified service technician to correct situation.
❏ Check for water leaks in boiler and piping; also check for leaks
around tankless heater plate, if installed. If found, immediately call
service technician to repair.
❏ Check float-type low water cutoff, when used: Refer to control
manufacturer’s instructions.
Scald potential. Do not blow down low water cutoff unless blow
down piping has been installed according to Boiler Manual. If
piping is not in place, call qualified service technician to install.
Periodically
during heating season
❏ Test probe-type low water cutoff, when used: refer to control
manufacturer’s instructions.
End
of heating season
❏ If tankless heater is installed, boiler will continue to operate. Check
for the following:
•All daily and weekly instructions listed on this page must be fol-
lowed.
•Burner motor may have to be oiled. Some motors are permanently
lubricated and do not need additional oil. Check for oiling instruc-
tions on burner or motor.
Boiler
shutdown
❏ Do not drain boiler unless exposure to freezing temperatures will
occur.
❏ Do not use antifreeze in steam systems.
❏ Always keep manual fuel supply shut off if burner is shut down for
an extended period of time.
•Turn off switch at boiler and any external switch to boiler.
•Close fuel valves.
•Turn off water feed valve.
•Cover burner to protect from dust and dampness.
Part number 550-142-330/0421
6
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
HOMEOWNERandSERVICETECHNICIAN—readandfollowcompletely.
Please read this before proceeding
Start-up
1. If burner does not fire, check for:
• Boilerswitchturnedoff?
• Fusesblownorbreakertripped?
• Thermostatsetbelowroomtemperature?
• Fuelvalvesturnedoff?
• Waternotvisibleingaugeglass?
• Notenoughoilintanktosupplyburner?
2. Correct problems found in step #1. If burner does
not fire, press the reset button on burner primary
control only once. Repeated presses will deposit oil
in chamber, creating a fire hazard.
Burner must never be fired when oil is in
combustion chamber. Immediately call a
qualified service technician.
3. If burner still does not fire, call a qualified service
technician.
❏ Check daily
Boiler area
•Check that boiler area is free from combustible materials,
gasoline and other flammable vapors and liquids. Ensure
that no air-contaminating materials (see page 10) are
present in the area.
Figure1 Boiler and components
Pressure gauge
•Pressure gauge must not show more than 15 psig
(normally 5 psig). Contact a qualified service techni-
cian if high pressure occurs.
Air openings
Verify that combustion and ventilation air openings to
the boiler room and/or building are open and unob-
structed.
❏ Check monthly
•Venting system, see page 39.
•Boiler and system piping, see page 39.
•Boiler relief valve, see page 40.
❏ Periodically
Oil motors equipped with oil cups
Burner motors may require oiling. Such motors are fit-
ted with oiling cups. Use a few drops only of SAE 20
detergent oil. Do not use household oils. Excessive
oiling can damage motors. Do not attempt to “fill up”
the oiling cup.
Test low water cutoff(s)
Probe-type low water cutoff
1. Turn off power to boiler
and wait 5 minutes.
2. Drain water to bottom of
gauge glass.
3. Turn on power.
4. Set thermostat to call for
heat. Red neon lamp on
low water cutoff should
light.
5. Wait 5 minutes. Boiler should not fire.
6. Refill boiler to correct water line. Red lamp should
go off.
7. Wait 5 minutes. Boiler should fire.
8. Return thermostat to normal setting.
Float-type low water cutoff (by others, if used)
Blow down control and test per control manufacturer’s
instructions.
Scald potential. Do not blow down low
water cutoff unless blow down piping
has been installed according to control
manufacturer’s instructions. If piping is not
installed, call a qualified service technician.
Part number 550-142-330/0421
7
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
HOMEOWNERandSERVICETECHNICIAN—readandfollowcompletely.
Troubleshooting
CommonproblemsCommoncausesPossiblecorrections
Rapid cycling -
burner
turns on and off frequently.
ermostat installed where dras or heat aect
reading.
Locate thermostat on inner wall away from heat sources or cool dras.
Heat anticipator setting in thermostat set
incorrectly.
Consult thermostat manufacturer instructions or set heat anticipator to
match current draw of circuit it is attached to. (Burner primary control, T-stat
switching relay coil, etc.).
Main and/or radiator vents not working properly
(one-pipe steam) or traps not working properly
(two-pipe steam).
Contact service technician to check, repair or replace air vents and traps.
Incorrect pressure limit setting. Set pressure cut-in and dierential according to system needs. Typical one and
two pipe systems need less than 2 psig. Typical cut-in setting is ½ -1 psi and
dierential of 1 psi. Try increasing dierential in ½ psi increments for longer
cycle times.
Frequent release of
water or steam through relief
valve.
Inoperative limit control.
If pressure in boiler is approaching 15 PSI, check pressure control setting,
operation & wiring. Replace if defective.
Incorrect or defective relief valve. Check for proper relief valve (15 psi). If opening at less than 15 psig, replace.
Needtofrequentlyadd
makeup water.
Leaks in boiler or piping.
Have qualied service technician repair leaks at once to avoid constant use of
makeup water.
Black or rust colored water
condition.
Black oxide or oxidation (rust) due to leaks in
boiler, air vents or piping. Improper pH.
Have qualied service technician repair leaks at once. Keep pH of water
between 7.0 to 8.5.
Popping or percolating noise
heard in boiler.
Mineral deposits in sections due to constant use
of makeup water. Or incorrect pH.
Have qualied service technician de-lime boiler and repair leaks at once to avoid
constant use of makeup water and check ph (7.0 to 8.5).
Metal flakes found in vent
outlet or vent — flue way
corrosion.
Contaminated combustion air supply. Remove any contaminating products. See page10 of this manual.
Provide outside air for combustion.
Condensation of combustion gases in ue ways. Have a qualied service technician check burner nozzle and oil pump pressure
for proper ring rate and check/adjust combustion settings with analyzer.
Some radiators or baseboard
units do not heat.
Main or radiator air vents (one pipe system) or
traps (two pipe system) not operating correctly.
Have qualied service technician inspect, repair or replace faulty air vents or
traps.
Incorrect pressure limit setting. Set pressure cut in and dierential according to system needs. Typical one and
two pipe systems need less than 2 psig. Typical cut in setting is ½ -1 psi and
dierential of 1 psi.
Clogged piping, valves or radiator. Or inoperable/
closed radiator valve.
Have qualied service technician clean or replace clogged components.
Water disappearing from
gauge glass and back into
system through return piping.
Incorrect Hartford loop piping. Have qualied service technician pipe boiler exactly as shown in boiler manual.
Check-valve inoperative. Have qualied service technician clean or replace check-valve.
Vacuum-breaker inoperative. Have qualied service technician clean or replace vacuum breaker.
Violent waterline fluctuations
surging
OR
Water passing into steam
mains priming.
Dirt, oil or other impurities in water. Have qualied service technician skim boiler.
Waterline too high. Have qualied service technician adjust waterline to normal height.
Incorrect piping. Have qualied service technician pipe boiler exactly as shown in boiler manual.
Sudden release of boiler steam pressure by action
of zone valves.
Have qualied service technician adjust valve operating time or install slow-
opening valves.
Domestic water from
tankless heater is hot then
suddenly turns cold.
Or
Domestic water from
tankless heater is always
lukewarm.
Mineral deposits insulate internal waterways of
heater.
Have qualied service technician delime or replace coil.
Boiler stop-leak compound has been added to
boiler water and is insulating outside of coil.
Have qualied service technician remove and clean coil and drain and ush
boiler to remove stop-leak.
Incorrect mixing valve setting for tankless heater. Have qualied service technician adjust mixing valve setting.
Domestic ow rate too high.
Have qualied service technician install ow check valve set to rating of
tankless heater.
Incorrect setting on tankless heater control.
Have qualied service technician raise tankless control setting. Adjust
dierential on tankless control to lower setting.
Homeowners — The problems and corrections below represent common situations that can occur.
There may be others not listed below. It is important always to contact a qualified service technician
if you have any questions about the operation of your boiler or system.
Part number 550-142-330/0421
8
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
HOMEOWNERandSERVICETECHNICIAN—readandfollowcompletely.
Top View
Walls
Floor
Ceiling
Wall
Figure2 Recommended service clearances
24"
C
A
B
D D
D
24"
AProvide 6" minimum clearance for service, provide 12" minimum clearance for
burner door swing.
BProvide 6" minimum clearance for service.
CProvide 6" minimum clearance for service, provide 15" left side with tankless heater.
DMinimum clearance from vent pipe to combustible material: 6" for type “L” double-
wall vent, 9" for single-wall vent.
Before installing boiler
Installations must comply with
United States
•State and local plumbing, heating and electrical codes.
•National codes where applicable.
•Standard for Controls and Safety Devices for Automatically Fired
Boilers, ANSI/ASME CSD-1, – latest edition, when required.
•National Electrical Code, ANSI/NFPA 70, – latest edition
and any additional national, state or local codes.
Canada
•Canadian Standards Association, CSA B139, Installation Code for
Oil-Burning Equipment - latest edition.
•CSA C22.1 Canadian Electrical Code Part One - latest edition.
•Applicable local or provincial codes.
Before selecting boiler location
Check for nearby connections to:
•System water piping.
•Chimney. See page 18. Boiler can be top or back vented.
•Combustion and ventilation air supply. See page 9.
•Oil supply. See page 32 for oil line routing.
•Electrical power.
Check area around boiler. Remove any combustible materials, gasoline and
other flammable liquids.
Provide clearances around boiler
(see Figure 2)
Jacket cap must be in place on boiler to
avoid requiring an 9" minimum clearance
from back or top of boiler to combustible
material.
MINIMUM clearances from vent pipe to combustible
material:
•6 inches — Type “L” double-wall vent
•9 inches — Single-wall vent
Flue pipe clearances must take precedence
over jacket clearances.
Recommended SERVICE clearances:
•24 inches — Front and top
• 6 inches — Left side, back and right side
•15 inches — Left side with tankless heater
•12 inches — Right side for burner door swing
radius
Failure to keep boiler area clear and free of combustible materials, gasoline and other flammable liquids and vapors
can result in severe personal injury, death or substantial property damage.
Homeowner—STOP! The procedures and information on this and following pages are intended only for a quali-
fied service technician who has the necessary equipment to inspect and adjust boiler and burner. A homeowner
should never attempt these procedures. The service technician must also read pages 1 through 7 before proceeding.
Part number 550-142-330/0421
9
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
HOMEOWNERandSERVICETECHNICIAN—readandfollowcompletely.
Table 1 Boiler foundation sizes
Provide air for combustion and ventilation
Do not install exhaust fan in boiler room.
Adequate combustion and ventilation air:
•Assures proper combustion.
•Reduces risk of severe personal injury or death from possible flue
gas leakage and carbon monoxide emissions.
Older buildings with single-pane windows, minimal weather-stripping
and no vapor barrier often provide enough natural infiltration and
ventilation without dedicated openings.
New construction or remodeled buildings are most often built tighter.
Windows and doors are weather-stripped, vapor barriers are used and
openings in walls are caulked. As a result, such tight construction is
unlikely to allow proper natural air infiltration and ventilation.
Follow state, provincial or local codes when sizing adequate combus-
tion and ventilation air openings. In absence of codes, use the follow-
ing guidelines when boiler is in a confined room (defined by NFPA
31 as less than 7200 cubic feet per 1 GPH input of all appliances in
area. A room 8 ft. high x 33.5 ft. x 33.5 ft. is 7200 cu. ft.):
•Provide two permanent openings — one within 12 inches of
ceiling, one within 12 inches of floor. Minimum height or length
dimension of each rectangular opening should be at least 3 inches.
•When inside air is used — each opening must freely connect with
areas having adequate infiltration from outside. Each opening
should be at least 140 sq. in. per 1 GPH input (1 sq. in. per 1000
Btu input) of all fuel-burning appliances plus requirements for
any equipment that can pull air from room (including clothes
dryer and fireplace).
When outside air is used — connect each opening directly or by ducts
to the outdoors or to crawl or attic space that freely connects with
outdoors. Size per below:
•Through outside wall or vertical ducts — at least 35 sq. in. per
1 GPH input (1 sq. in. per 4000 Btu input) of all fuel-burning
appliances plus requirements for any equipment that can pull
air from room (including clothes dryer and fireplace).
•Through horizontal ducts — at least 70 sq. in. per 1 GPH
boiler input (1 sq. in. per 2000 Btu input) of all fuel-burning
appliances plus requirements for any equipment that can pull
air from room (including clothes dryer and fireplace).
•Where ducts are used, they should have same cross-sectional
area as free area of openings to which they connect. Com-
pensate for louver, grille or screen blockage when calculating
free air openings. Refer to their manufacturer’s instructions
for details. If unknown, use:
•Wood louvers, which provide 20-25% free air.
•Metal louvers or grilles, which provide 60-75% free air.
Lock louvers in open position or interlock with equipment to prove
open before boiler operation.
Lay a foundation, if needed
Boiler may be installed on non-carpeted combustible
flooring.
For residential garage installation, install boiler so burner is
at least 18 inches above floor to avoid contact with gasoline
fumes.
A level concrete or masonry foundation is required when:
•Floor could possibly become flooded.
•Non-level conditions exist.
Solid concrete blocks can be used to create a pad.
Boiler
model
Length
inches
Width
inches
Minimum
height
inches
SGO-3
17 22 2
SGO-4
20 22 2
SGO-5
23 22 2
SGO-6
26 22 2
SGO-7
29 22 2
SGO-8
32 22 2
SGO-9
35 22 2
Before installing boiler (continued)
Part number 550-142-330/0421
10
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
HOMEOWNERandSERVICETECHNICIAN—readandfollowcompletely.
Air contamination
Please review the following information on potential
combustion air contamination problems.
See Table 2 for products and areas which may cause
contaminated combustion air.
To prevent potential of severe personal injury
or death, check for products or areas listed
below before installing boiler. If any of these
contaminants are found:
•removecontaminantspermanently.
—OR—
•isolateboilerandprovideoutsidecombustionair.
See national, provincial or local codes for further
information.
•Contact your qualified service technician to install
an outside air kit (if available) for the burner. An
outside air kit allows ducting of outside air directly
to the burner.
Before installing boiler
continued
Table 2 Corrosive contaminants and likely locations
Products to avoid
Spray cans containing chloro/uorocarbons
Permanent wave solutions
Chlorinated waxes/cleaners
Chlorine-based swimming pool chemicals
Calcium chloride used for thawing
Sodium chloride used for water softening
Refrigerant leaks
Paint or varnish removers
Hydrochloric acid/muriatic acid
Cements and glues
Antistatic fabric softeners used in clothes dryers
Chlorine-type bleaches, detergents, and cleaning solvents
found in household laundry rooms
Adhesives used to fasten building products and other similar
products
Areas likely to have contaminants
Dry cleaning/laundry areas and establishments
Swimming pools
Metal fabrication plants
Beauty shops
Refrigeration repair shops
Photo processing plants
Auto body shops
Plastic manufacturing plants
Furniture renishing areas and establishments
New building construction
Remodeling areas
Garages with workshops
Part number 550-142-330/0421
11
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
HOMEOWNERandSERVICETECHNICIAN—readandfollowcompletely.
Operation
SGO with float-type low water cutoff
1. If burner does not fire, check for:
•Switch on boiler or additional shut-off switches turned
off.
•Fuses or breaker switch tripped.
•Thermostat set below room temperature.
•Fuel valves turned off.
•Not enough oil in tank to supply burner.
•No water in gauge glass.
2. Correct problems found in Step #1. If burner does not fire,
press reset button on burner primary control only once.
Repeated presses will deposit oil in combustion chamber.
Burner must never be fired when oil is in combus-
tion chamber. Immediately call qualified service
technician.
3. If burner still does not fire, call qualified service technician.
Figure3 SGO boiler with float-type low water cutoff (see Figure 4, page 12 for probe-type low water cutoff)
Gauge glass
Steam relief valve
(on back of boiler)
Tankless heater
control
located
in tankless
heater plate
(sizes 3-5)
or in tapping in
back section
(sizes 6-9)
Float-type
Low water cutoff
Pressure
control
Pressure
gauge
Burner
primary
control
Service
switch
On boiler
Reset button
on burner
primary
control
Burner
disconnect
plug
Part number 550-142-330/0421
12
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
HOMEOWNERandSERVICETECHNICIAN—readandfollowcompletely.
2. Correct problems found in Step #1. If burner does not fire,
press reset button on burner primary control only once.
Repeated presses will deposit oil in combustion chamber.
Burner must never be fired when oil is in combus-
tion chamber. Immediately call qualified service
technician.
3. If burner still does not fire, call qualified service technician.
SGO with probe-type low water cutoff
1. If burner does not fire, check for:
•Service switch on boiler or additional switches turned off.
• Fuses or breaker switch tripped.
•Thermostat set below room temperature.
•Fuel valves turned off.
•Not enough oil in tank to supply burner.
•No water in gauge glass.
Figure4 SGO boiler with probe-type low water cutoff (see Figure 3, page 11 for float-type low water cutoff)
Steam relief valve
(on back of boiler)
Gauge glass
Probe-type
low water
cutoff
Reset button
on burner
primary
control
Tankless heater
control
located in
tankless heater
plate
(sizes 3-5)
or in tapping in
back section
(sizes 6-9)
Pressure control
Pressure gauge
Burner
primary
control
Burner
disconnect
plug
Service
switch
on boiler
Operation (continued)
Figure5 Change from back flue outlet to top flue outlet (optional)
Instructions for Packaged boilers continued on page 18.
Install boiler — packaged boilers only
Part number 550-142-330/0421
13
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
SERVICETECHNICIANONLY—readandfollowcompletely.
Place boiler
1. Remove boiler from pallet.
Do not drop boiler or bump jacket on
floor or pallet. Damage to boiler can
result.
Smaller sized boilers may be top heavy.
Use caution when handling to avoid mi-
nor personal injury or property damage.
2. The boiler is shipped for back flue outlet. To change
to top flue outlet (see Figure 5):
a. Remove the jacket cap and the 8.00” diameter
piece of insulation that covers the vent opening
from the top jacket panel.
b. Loosen two (2) screws holding flue cap strap
to collector hood. Remove strap and flue cap
from opening. Re-tighten screws.
c. Check rope placement inside flue cap.
(Read under Step #5 below).
d. Loosen two (2) screws on back flue outlet. Set
flue cap on outlet. Install strap by engaging
slots in screws. Tighten screws. Make sure cap
is securely installed.
e. Place the jacket cap insulation disc in the back
opening of the boiler covering the flue cap.
f. Snap jacket cap in back outlet opening.
Jacket cap and insulation disc must be in
place on boiler to avoid requiring an 18"
minimum clearance from back of boiler
to combustible material.
3. Check level. Shim legs, if needed.
4. Check for secure placement of insulation on tar-
get wall, chamber floor and burner door.
5. Visually check:
a. Flue collector hood seal.
b. Burner mounting door seal.
Obtain gas-tight seal to prevent possible
flue gas leakage and carbon monoxide
emissions, which can lead to severe per-
sonal injury or death.
Tankless heater, if used
1. Remove tankless heater knockout in left side of
jacket panel and, for SGO-6 only, tankless heater
control knockout.
2. Remove tankless heater cover plate and gasket.
3. Install new gasket and tankless heater over studs
around opening. Secure with 3/8" nuts.
4. Install tankless heater operating control where
shown on page 25. If not furnished, use operating
control with maximum 10°F differential.
Perform hydrostatic pressure test
1. Remove steam pressure gauge furnished with boiler. Install water pres-
sure gauge for test only. Be sure gauge can handle test pressure.
2. Install air vent in tapping on top of boiler.
3. Remove pressure control and low water cutoff. Plug tappings.
4. Plug supply and return tappings.
5. Drain valve is already factory-installed.
6. Fill boiler. Vent all air. Pressure test boiler at 45-55 psig.
Do not leave boiler unattended. Cold water fill can expand
and damage cast iron, resulting in severe personal injury,
death or substantial property damage.
7. Check for maintained gauge pressure for more than 10 minutes. Visu-
ally check for leaks if gauge pressure drops.
8. Drain boiler. Repair leaks if found.
Using petroleum-based compounds to repair leaks can dam-
age system components, resulting in property damage.
9. Retest boiler after repairing leaks.
10. Remove pressure gauge, air vent and plugs. Re-install steam pressure
gauge, pressure control and low water cutoff furnished with boiler.
Part number 550-142-330/0421
14
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
SERVICETECHNICIANONLY—readandfollowcompletely.
Fiberglass wool and ceramic fiber materials are
possible cancer hazards. See warning on page 48.
Place boiler
1. Semi-packaged SGO-3 through 6 — position on site.
Smaller sized boilers may be top heavy. Use caution
when handling to avoid minor personal injury or
property damage.
a. Boiler is shipped for back flue outlet. To change to top flue
outlet (see Figure 6, page 15):
• Remove the jacket cap and the 8.00” diameter piece
of insulation that covers the vent opening from the
top jacket panel.
•Loosen two (2) screws holding flue cap strap
to collector hood. Remove strap and flue cap from
opening. Re-tighten screws.
• Check rope placement inside flue cap.
(Read
under Step #3 at right).
•Loosen two (2) screws on back flue outlet. Set flue
cap on outlet. Install strap by engaging slots in screws.
Tighten screws. Make sure cap is securely installed.
•Place the jacket cap insulation disc in the back opening
of the boiler covering the flue cap.
•Snap jacket cap in back outlet opening.
Jacket cap and insulation disc must be in place on
boiler to avoid requiring an 18” minimum clearance
from back of boiler to combustible material.
2. Knocked-down SGO-7, 8 & 9 — split the assembled block for
easier handling (see Figure 6):
a. Open burner mounting door and using utility knife, slit
floor insulation at joint to be separated.
b. Remove 5½" draw rod and the longest draw rod from each
side. Pull block apart. Save draw rods, nuts, washers and
sealing rings for reassembly.
c. Move divided block to location.
d. Clean port openings with clean rag.
Do not use petroleum-based compounds to clean
openings. Damage to system components can result
causing property damage.
e. Place rings in port openings. If ring slips out of groove,
stretch ring gently for several seconds, then place in groove.
f. Position sections so aligning lugs fit into sockets of next
section. Make sure sealing rope is in good condition and
in position.
Install boiler –
Semi-packaged and Knocked-down boilers only
g. Oil threads on draw rods. Install washer and nut on end
to be tightened. Use nut only on other end.
h. With wrench at washer/nut end, uniformly
tighten nuts starting with 5½" rod at large port, 5½" rod
at small port, bottom long rod and finally top long rod.
i. Torque on both 5½” rods and bottom long rod should
be 50-60 ft. lbs.; long top rod should be 20-25 ft. lbs. Do
not back-off nuts.
j. Metal-to-metal contact should be made around port
openings. If gap does exist, it should be less than .020”.
Check with feeler gauge.
k. If gap around port openings exceeds .020”, check for dirt
on port openings, sockets or misaligned lugs. If corrections
are made and gap still exists, contact our Technical Services
group for assistance before continuing installation.
3. Knocked-down SGO-3 through 9 — install flue collector hood
(see Figure 6):
Obtain gas-tight seal to prevent possible flue gas
leakage and carbon monoxide emissions, leading
to severe personal injury or death.
a. Thread Tinnerman clip on screw so that clip fits snugly
in notch of hold-down lug. Screw must not turn.
b. Remove paper on sealing rope. Starting at back section
near flue collar, position sealing rope around top of block
with adhesive side to sections. Do not stretch rope. Make
sure rope ends meet. Trim excess rope.
c. Position flue collector hood on top of boiler sections and
over screws and clips as shown in Figure 6.
d. Install washers and nuts. Tighten nuts until collector hood
makes contact with Tinnerman clip.
e. Position flue cap
• Back flue outlet boiler — Position flue cap and strap
over opening in flue collector hood. Make sure rope
in cap is in place and in good condition. Tighten strap
to hood with screws provided.
• Top flue outlet boiler — Position flue cap and strap
over opening in back section. Make sure rope in cap is
in place and in good condition. Tighten strap to boiler
with screws provided in section. Install remaining
screws in holes in flue collector hood.
4. Check level. Shim legs, if needed.
Tankless heater, if used
1. SGO-3 through 6 — remove knockout in left side jacket panel,
and for SGO-6 only, remove tankless heater control knockout.
2. Remove tankless heater cover plate and gasket.
3. Install new gasket and tankless heater over studs around open-
ing. Secure with 3/8” nuts.
Part number 550-142-330/0421
15
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
SERVICETECHNICIANONLY—readandfollowcompletely.
Figure6 Change from back flue outlet to top flue outlet (optional)
Install boiler –
Semi-packaged and Knocked-down boilers only (continued)
Sealing
rope in
groove
inside cap
Flue
cap
Flue cap
strap
Flue
collector
hood
Sealing
rope with
adhesive
tape
Nut
Washer
Tinnerman
clip
Screw
Hold-down
lug
Separate
block
here
for easier
handling
Part number 550-142-330/0421
16
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
SERVICETECHNICIANONLY—readandfollowcompletely.
LocationSizeFunction
A1 1½" Skim tapping
A2 2½" Supply piping (sizes 3 - 9)
A3 2½" Supply piping (sizes 6 - 9)
B1 1½" Plugged
B2 2" Return piping
E1 & E2 ½" Float LWCO
E1 ½"
Steam pressure gauge and limit
Control when using probe LWCO
E2 ½" Plugged when using probe LWCO
H ¾" Drain valve
L ¾"
Steam pressure gauge and limit
Control when using float LWCO
Plugged when using probe LWCO)
P ¾" Probe LWCO (plugged when using float LWCO)
R ¾" Relief valve
S1 & S2 ½" Gauge glass
U1 1"
Indirect-fired water heater/ hot water
baseboard supply
U2 ¾"
Operating control for tankless heater (sizes
6-9) or operating control for indirect-fired water
heater (sizes 3-9)
U3 ¾"
Operating control for tankless heater (located
in heater plate — sizes 3-5)
Perform hydrostatic pressure test
1. Refer to Figure 7 and Control Tapping Table 3, to
install:
a. Boiler drain.
b. Water pressure gauge (test only). Be sure gauge
can handle test pressure.
c. Air vent in tapping on top of boiler.
d. Plugs in remaining tappings.
2. Fill boiler. Vent all air. Pressure test boiler at 45-55
psig.
Do not leave boiler unattended. Cold
water fill could expand and damage cast
iron, resulting in severe personal injury,
death or substantial property damage.
3. Check for maintained gauge pressure for more
than 10 minutes. Visually check for leaks if gauge
pressure drops.
4. Drain boiler. Repair leaks if found.
Do not use petroleum-based compounds
to repair leaks. Damage to system com-
ponents can result, causing property
damage.
5. Re-test boiler after repairing leaks.
6. Remove pressure gauge, air vent and plugs from
tappings used for controls.
7. Visually check:
a. Sealing rope placement
b. Metal-to-metal contact around port openings.
c. Flue collector hood seal.
d. Burner mounting door seal.
Obtain gas-tight seal to prevent possible
flue gas leakage and carbon monoxide
emissions, which can lead to severe per-
sonal injury or death.
Table 3 Control tappings (see Figure 7, page 17 for locations)
Install jacket
(Knocked-down boilers only)
Before installing jacket, remove burner mounting door.
See jacket instructions for details.
Install boiler controls
See control tapping location, Figure 7, control tappings,
Table 3, and Figure 8 or Figure 9 on page 17 to install
controls.
1. Do not use Teflon tape to install probe-type low
water cutoff; it will cause low water cutoff to work
improperly.
2. Install tankless heater control if tankless heater is
used. If not furnished, use operating control with
maximum 10°F differential.
3. Make sure gauge glass is last control installed to
prevent breakage.
4. Affix Consumer Protection (CP) number label(s)
on jacket front panel.
Install boiler –
Semi-packaged and Knocked-down boilers only (continued)
Figure7 Control tapping
locations
(for use with
Table 3, page 16)
U3
FrontSection
A1 A2S1
L
P
B1
H
S2
E2
E1
BackSection
R U1
U2
A3
B2
Figure8 Steam boiler controls with float-type LWCO (optional tankless heater
control)
Figure9 Steam boiler controls with probe-type LWCO (optional tankless heater
control)
Siphon
SGO-3 to SGO-5
tankless heater
control
SGO-6 to SGO-9
tankless heater
control
Steam pressure
Steam pressure
Probe-type
low water
cutoff
Gauge glass
and cocks
Drain valve
Part number 550-142-330/0421
17
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
SERVICETECHNICIANONLY—readandfollowcompletely.
Install boiler –
Semi-packaged and Knocked-down boilers only (continued)
SGO 3-5 tankless
heater control
location
SGO 6-9 tankless
heater control
location
Float-type low
water cutoff
Steam pressure
control
Steam pressure
gauge
Gauge glass
and cocks
Drain valve
Siphon
Part number 550-142-330/0421
18
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
SERVICETECHNICIANONLY—readandfollowcompletely.
Connect breeching
Connect breeching
Long horizontal breechings, excessive number of tees
and elbows, or other obstructions restricting combus-
tion gas flow can result in possibility of condensation,
flue gas leakage and carbon monoxide emissions,
which can lead to severe personal injury or death.
1. Install two (2) flue pipe brackets.
2. Connect full-sized breeching when possible. See Minimum
Chimney Size Table 4.
•Back outlet — see Figures 10 and 11, page 19.
•Top outlet — see Figures 13 and 12, page 19.
3. Connection must be made above bottom of chimney to avoid
blockage. Breeching must not enter chimney far enough to cause
obstruction. Use thimble or slip joint where breeching enters
chimney to allow removal for cleaning.
4. When burner and boiler are properly installed, draft over fire
will be approximately -0.01" to -0.02" W.C. Install barometric
control in breeching, per control manufacturer’s instructions,
when excess draft needs to be relieved or to comply with ap-
plicable codes and regulations. Use draft gauge to adjust proper
opening.
5. An induced draft fan for the chimney may be necessary if:
•Excessive resistance to flow of combustion gases can be
expected.
•Cross-sectional area of chimney is smaller than minimum
recommended.
•Chimney height is less than recommended.
Seal all vent joints. Interlock burner with fan opera-
tion.
6. Boiler models SGO-3 through SGO-7 require the installation of
the Field Controls OVD-7 damper, Weil-McLain part number
381-800-515, which is provided with Packaged boilers, sold
separately for Semi-packaged and Knocked-down boilers.
Refer to Figures 10 and 13, page 19.
Install burner
(also refer to instructions packed with burner)
Use only burners specified for use on Weil-
McLain oil boilers. Contact individual burner
manufacturers for proper burner selections.
For burners with OEM welded flanges:
1. Secure mounting flange and gasket to burner mounting
door. Use three (3) bolts provided.
2. Open door to verify secure placement of insulation on
target wall, chamber floor and burner mounting door.
3. Securely close door and tighten nut.
For burners without OEM welded flanges:
1. Secure universal mounting flange and gasket to burner
mounting door. Use three (3) bolts provided.
2. Secure burner on flange with three (3) bolts.
3. Position burner so end of air tube is level to 1½-degree tilt
down toward chamber. Open door to verify burner position.
End of air tube should be flush to ¼" recessed from inside
wall of burner door refractory. Check for secure placement
of insulation on target wall, chamber floor and burner
mounting door.
4. Securely close door and tighten nut.
General chimney requirements
Designed for natural draft firing. Connect boiler to vertical
chimney.
Insufficient draft can cause flue gas leakage and
carbon monoxide emissions, which will lead to
severe personal injury or death.
Use vent material approved by local codes for oil-fired burners.
In their absence, refer to:
•NFPA 31- latest edition, Installation of Oil-Burning
Equipment.
•NFPA 211- latest edition, Standard for Chimneys, Fire-
places, Vents and Solid Fuel Burning Appliances.
•In Canada, refer to CSA B139, Installation Code for Oil-
Burning Equipment.
NFPA 211 requires chimney to be lined before connected to
boiler.
Inspect existing chimney before installing new boiler.
Failure to do any of the following will result in severe
personal injury or death.
•Clean chimney, including removal of blockage.
•Repair or replace damaged pipe or liner.
•Repair mortar and joints.
To prevent downdrafts, extend chimney at least 3 feet above highest
point where it passes through roof and 2 feet higher than any portion
of building within 10 feet. Increase chimney cross-sectional area and
height at least 4% per 1,000 feet above sea level.
•Minimum clearances from vent pipe to combustible material:
• 6 inches — Type “L” double-wall vent
• 9 inches — Single-wall vent
•Minimum chimney sizes should be used.
Oversized chimneys, outside masonry chimneys and/or
derated inputs can result in condensation in chimney.
Boiler
model
number
Minimum
breeching
diameter
(Note 3)
Minimum
chimney size Minimum
chimney
heightRect. Round
SGO-3 5"
8" x 8"
(Note 1)
6" 15'
SGO-4 6"
SGO-5 6"
8" x 8"
(Note 1)
7" 15'SGO-6
7"
SGO-7
SGO-8
7"
8" x 12"
(Note 2)
7" 20'
SGO-9
NOTES:
1. 6¾” x 6¾” inside liner.
2. 6½” x 10½” inside liner.
3. Flue collar on boiler is 7” diameter.
Table 4 Minimum chimney sizes
Install burners and chimney — all boilers
Part number 550-142-330/0421
19
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
SERVICETECHNICIANONLY—readandfollowcompletely.
Figure10 Back outlet breeching connection for
SGO-3 through 7 with OVD damper.
Connect breeching (continued)
Figure11 Back outlet breeching connection for SGO-8 and
SGO-9
Figure12 Top outlet breeching connection for
SGO-8 and SGO-9
Figure13 Top outlet breeching connection for
SGO-3 through 7 with OVD damper.
Typical location for
barometric control
(Also see control
manufacturer’s
instructions)
Flue pipe
bracket
(One on each
side of pipe)
Typical location for
barometric control
(Also see control
manufacturer’s
instructions)
Flue pipe bracket
(One on each
side of pipe)
0251-056_OVD
OVD Damper
(Required)
BVSS
(WMO-1)
(Integrated with damper)
BVSS must be installed
upstream of the barometric
damper.
Typical location for
barometric control
(Also see control
manufacturer’s
instructions)
Flue pipe
bracket
(One on each
side of pipe)
0250-056_OVD
OVD
Damper
(Required)
Flue pipe
bracket
(One on each
side of pipe)
Typical location for
barometric control
(Also see control
manufacturer’s
instructions)
BVSS
(WMO-1)
(Integrated with damper)
BVSS must be installed
upstream of the
barometric damper.
General piping information
•Hartford Loop piping arrangement and wet return are required for
steam boilers.
•Maintain 24-inch minimum from waterline to bottom of header
(minimum 50
7
/8" from floor or top of foundation).
•When using condensate receiver, feed pump must be energized by
boiler-mounted pump control.
•Use swing joints in steam piping.
•If installation is to comply with ASME or Canadian requirements, an
additional pressure limit control is needed. Install control between
existing pressure control and pressure gauge. Control must be installed
with siphon (supplied with boiler) between control and boiler. Set
control to minimum of 5 psi above set point of existing control and
maximum setting of 15 psi. Wire as shown on boiler wiring diagram.
Install piping
1. See Table 5 at right and Figure 14, page 21 or Figure 15, page 22.
Improperly piped systems or undersized piping can con-
tribute to erratic boiler operation and possible boiler
or system damage. Piping system must be installed as
shown, using minimum pipe sizes shown. Consult your
Weil-McLain distributor or sales office before installing
alternate piping.
2. Install relief valve vertically in “R” tapping on back of boiler. See
Figure 14 or Figure 15 and also refer to tag attached to relief valve for
manufacturer’s instructions.
Pipe relief valve discharge line near floor close to floor drain
to eliminate potential of severe burns. Do not pipe to any
area where freezing could occur. Do not plug, valve or place
any obstruction in discharge line.
3. Float-type low water cutoff only — install blow down line in bottom
of cutoff. See Figure 14 or Figure 15 and also refer to low water cutoff
manufacturer’s instructions for details.
Pipe blow down line near floor close to floor drain to eliminate
potential of severe burns. Do not pipe to any area where freez-
ing could occur. Do not plug, valve or place any obstruction
in discharge line.
To connect SGO boilers to indirect-fired water
heaters
Install and wire per water heater manual provided with water heater.
If boiler already has a tankless heater installed:
•Remove tankless heater and install cover plate.
OR
•Leave tankless heater installed. Drain coil and remove piping. Do not
plug holes in tankless heater front plate.
Connect steam piping
Table 5 Steam piping size table
Oneandtwo-pipesystems
Boiler
Model
Number
RiserPipe
Size
(Note1)
Header
PipeSize
“H”
(Note2)
Equalizer
Pipe
Size
“J”
AB
SGO-3
2½"
(Note3)
— 2½” 1½"
SGO-4
2½"
(Note3)
— 2½" 1½"
SGO-5 2½" — 3" 1½"
SGO-6 2½" 2½" 3" 1½"
SGO-7 2½" 2½" 3" 1½"
SGO-8 2½" 2½" 3" 1½"
SGO-9 2½" 2½" 3" 1½"
One-pipecounterowsystems
SGO-3 2½" — 2½” 1½"
SGO-4 2½" — 2½" 1½"
SGO-5 2½" — 3" 1½"
SGO-6 2½" 2½" 4" 1½"
SGO-7 2½" 2½" 4" 1½"
SGO-8 2½" 2½" 4" 1½"
SGO-9 2½" 2½" 4" 1½"
Note1
Based on ASHRAE Fundamentals
Handbook recommendations, allowing ½
oz. pressure drop at 0 psig.
Note2
Based on ASHRAE Fundamentals
Handbook recommendations, allowing 2
oz. pressure drop per 100 feet of pipe at 3.5
psig. Maintain minimum 24" height from
waterline to bottom of header.
Note3
Can be reduced to 2".
Part number 550-142-330/0421
20
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
SERVICETECHNICIANONLY—readandfollowcompletely.
Connect steam piping (continued)
Figure14 Steam piping for sizes 3 through 5 (see Figure 15, page 22, for sizes 6 through 9)
Part number 550-142-330/0421
21
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
SERVICETECHNICIANONLY—readandfollowcompletely.
Part number 550-142-330/0421
22
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
SERVICETECHNICIANONLY—readandfollowcompletely.
Figure15 Steam piping for sizes 6 through 9 (see Figure 14, page 21 for sizes 3 through 5)
Connect steam piping (continued)
Figure16 Typical piping (one riser shown on boiler)
Part number 550-142-330/0421
23
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
SERVICETECHNICIANONLY—readandfollowcompletely.
Table 6 Condensate receiver capacity
Boiler
Model
GrossOutput
lbssteam
perhour
Gallons
condensate
perhour
Minimumcondensatereceivercapacity–gal.
Recommended
condensatefeed
pumpingrategpmat
15psi
15Min.*
Boiler
operation
30Min.*
Boiler
operation
45Min.*
Boiler
operation
60Min.*
Boiler
operation
SGO-3
114 14 4 8 12 16 0.5
SGO-4
150 18 5 11 16 22 0.6
SGO-5
180 22 6 13 19 26 0.7
SGO-6
216 26 8 16 23 31 0.9
SGO-7
246 30 9 18 27 35 1.0
SGO-8
274 33 10 20 30 39 1.1
SGO-9
303 36 11 22 33 44 1.2
* Maximum time to when condensate returns to boiler.
Optional reservoir piping
Modern steam boilers are designed to steam for less
time than older, larger boilers. When replacing an older
steam boiler, the system condensate return time may
be longer than the steaming time. This can cause the
following problems:
•Boilers fitted with an automatic water feed could
overfill.
•Units fitted with only a low water cutoff would
shut down and cycle while waiting for condensate
to return.
To size and install reservoir piping :
1. Pipe boiler as shown on page 20 through page 22.
2. Use 8" diameter reservoir pipe.
3. Locate centerline of reservoir pipe 1" below 26
7
/8" boiler waterline.
Connect steam piping (continued)
Connect tankless heater piping
Part number 550-142-330/0421
24
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
SERVICETECHNICIANONLY—readandfollowcompletely.
Table 7 Tankless heater ratings
Boiler
model
number
Heater
number
Intermittent
draw
ratings
(gpm)*
Inlet and Outlet
tapping sizes
SGO-3 35-S-29 3.25 ¾"
SGO-4 35-S-29 3.50 ¾"
SGO-5 35-S-29 3.75 ¾"
SGO-6 35-S-29 4.00 ¾"
SGO-7 35-S-29 4.00 ¾"
SGO-8 35-S-29 4.00 ¾"
SGO-9 35-S-29 4.00 ¾"
NOTES:
1. To avoid supplying steam to system during summer tankless operation, raise water level to one inch
above normal water line.
2. Gallons of water per minute heated from 40°F to 140°F with 200°F boiler water temperature. Tested in
accordance with AHRI testing and rating standard for indirect tankless water heaters tested with boilers.
Hot Water Can Scald!
•Consumer Product Safety Commission and
some states recommend domestic hot water
temperature of 130°F or less.
•When installing an automatic mixing valve,
selection and installation must comply with
valve manufacturer’s recommendations and
instructions.
•Water heated to a temperature suitable for
clothes washing, dish washing and other sanitiz-
ing needs will scald and cause injury.
•Children, elderly, infirm or physically handi-
capped persons are more likely to be injured
by hot water. Never leave them unattended in
or near a bathtub, shower or sink. Never allow
small children to use a hot water faucet or draw
their own bath. If anyone using hot water in the
building fits this description, or if state laws or
local codes require certain water temperatures
at hot water faucets, take special precautions:
•Install automatic mixing valve set according
to those standards.
•Use lowest practical temperature setting.
•Check water temperature immediately after
first heating cycle and after any adjustment.
To pipe tankless heater
1. Size piping no smaller than tankless heater inlet and
outlet.
2. Following controls (furnished by others) must be in-
stalled:
a. Automatic mixing valve. See Figure 17.
(Read
at left.)
b. Flow regulating valve. Size according to intermittent
draw of tankless heater. See Table 7 below. Follow
valve manufacturer’s instructions to install.
3. Additional anti-scald devices may be installed at each
hot water faucet, bath and shower outlet.
4. In hard water areas, soften cold domestic supply water
to heaters to prevent lime build-up.
Studies have indicated that dangerous
bacteria can form in potable water distri-
bution systems if certain minimum water
temperatures are not maintained. Contact
local health department for more informa-
tion.
Tankless water heaters for SGO boilers
have been tested and certied by
CSA Group (certicate # 2552127).
NSF/ANSI372
SGO 3-5 tankless
heater control location
SGO 6-9 tankless heater
control location
Flow
regulating valve
Automatic
mixing valve
Mixed
Hot
Cold
Cold water
supply
12" Min.
Connect tankless heater piping (continued)
Part number 550-142-330/0421
25
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
SERVICETECHNICIANONLY—readandfollowcompletely.
ese single wall heat exchangers comply with National Standard
Plumbing Code provided that:
•Boiler water (including additives) is practically non-toxic,
having a toxicity rating or class of 1, as listed in Clinical
Toxicology of Commercial Products.
•Boiler water pressure is limited to max. 15psig by approved
steam relief valve.
Figure17 Tankless heater piping
Connect wiring — general information
Part number 550-142-330/0421
26
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
SERVICETECHNICIANONLY—readandfollowcompletely.
General wiring requirements
ELECTRIC SHOCK HAZARD – Can cause severe
personal injury or death if power source, includ-
ing service switch on boiler, is not disconnected
before installing or servicing.
Installations must follow these codes:
•National Electrical Code, ANSI/NFPA 70, – latest edi-
tion and any additional national, state or local codes.
• In Canada, CSA C22.1 Canadian Electrical Code Part
One – latest edition and any local codes.
•Wiring must be NEC Class 1 – latest edition. If original
wire as supplied with boiler must be replaced, type 105°C
wire or equivalent must be used. Supply wiring to boiler
and additional control wiring must be 14 gauge or heavier.
•Provide electrical ground at boiler as required
by codes.
Thermostat wiring
•Install thermostat on inside wall away from influences of
drafts, hot or cold water pipes, lighting fixtures, television,
sun rays or fireplaces.
•Follow instructions with thermostat. If it has a heat antici-
pator, set heat anticipator in thermostat to match power
requirements of equipment connected to it. Boiler wiring
diagrams give setting for standard equipment.
Junction box (furnished)
•Junction box houses electrical connections for all boiler
components.
•Packaged boilers have harnesses furnished.
•For Semi-packaged and Knocked-down boilers, trim kits
are furnished with burner and limit harnesses.
•All field-provided high voltage wiring must be sheathed in
flexible metal conduit.
•Connect incoming line voltage “HOT” wire to service
switch, and neutral wire to white wire. Field-install equip-
ment ground wire to green wire with wire nut.
•Service switch (15 amp) is provided with boiler.
For Semi-packaged and Knocked-down boilers —
install switch as shown.
•Some local codes may require an emergency shut-
off switch installed at a location away from boiler.
Follow local codes.
Burner wiring
•Burner wire harness incorporates a disconnect plug,
providing a convenient way to disconnect wiring
when burner mounting door is opened.
•All Packaged boilers have a power disconnect plug
installed on the service switch junction box.
•The burner is provided with a burner discon-
nect plug as shown in Figure 20, page 29, or Fig-
ure 23, page 31. For burners in which the disconnect
plug is not factory-wired, connect the threaded
conduit coupling of the disconnect plug wire har-
ness (P/N 591-391-850, included in steam trim
carton) to the burner housing and route the wires
to make all connections in burner junction box as
shown in boiler wiring diagram.
High temperature limit
•To comply with ASME, UL 726 or Canadian re-
quirements, an additional high temperature limit
is needed.
•Install the secondary control in the supply piping
between boiler and isolation valve.
•Set the control to a minimum of 20˚F above the set
point of the combination control.
•The maximum allowable set point is 220˚F.
•Wire the control as shown on page 28 (float-type
LWCO) or page 30 (probe-type LWCO).
Connect wiring — general information (continued)
Figure18 Blocked vent shutoff switch installation
Part number 550-142-330/0421
27
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
SERVICETECHNICIANONLY—readandfollowcompletely.
Blocked vent shutoff switch
Electric shock hazard – Turn off electri-
cal power supply at service entrance panel
before making any electrical connections to
avoid possible electric shock hazard. Failure
to do so can cause severe personal injury
or death.
In Canada, a blocked vent shutoff switch
kit must be installed (see replacement parts
list page 42). See Figure 28.
When using the OVD damper kit, the
BVSS is required, and is integrated into the
damper harness wiring.
When using the BVSS without the OVD
damper, the BVSS is wired directly to the
junction box as follows.
The BVSS wiring diagram in Figure 24, page 31 shows
boiler wiring up to the burner disconnect. For addi-
tional information, refer to manufacturer’s installation
instructions.
AfterinstallingBVSSswitch,proceedasfollows
1. Disconnect power.
2. Install BVSS Switch Wiring Harness (P/N 591-391-
942, which is included in BVSS kit P/N 591-624-650)
as follows:
a. Remove cover from BVSS Box.
b. Install straight fitting end of the harness on the
BVSS Box. Install elbow (90º) end fitting on the
Boiler Junction Box (see Figure 18).
c. Install both the fork ends to the screw terminals
on the BVSS Switch as per the wiring diagram,
(see Figure 21, page 29).
d. Replace BVSS box cover.
Towireblockedventshutoffswitch,see:
Figure 19, page 28 for float-type LWCO
Figure 22, page 30 for probe-type LWCO
Connect wiring (Float-typeLWCO)
Figure19 Boiler wiring for float-type LWCO — see Figure 20, page 29 for component locations
Part number 550-142-330/0421
28
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
SERVICETECHNICIANONLY—readandfollowcompletely.
Connect wiring (Float-typeLWCO) (continued)
120 VAC field wiring 120 VAC factory wiring
1 Pressure control wiring harness
2 Tankless heater control wiring
3 Burner disconnect plug
4 Burner wiring harness
5 Low water cutoff wiring harness (not
furnished on Semi-packaged and Knocked-
down boilers).
Part number 550-142-330/0421
29
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
SERVICETECHNICIANONLY—readandfollowcompletely.
Figure20 Boiler wiring for float-type LWCO —
component locations for wiring diagram,
Figure 19, page 28
Figure21 BVSS wiring diagram (float-type LWCO)
Blocked vent shutoff switch (BVSS),
when required
In Canada, a blocked vent shutoff switch kit
must be installed (see parts list page 42). See Fig-
ure 18, page 27.
When using the OVD damper kit, the BVSS is re-
quired, and is integrated into the damper harness
wiring.
When using the BVSS without the OVD damper, the
BVSS is wired directly to the junction box as follows.
The BVSS wiring diagram in Figure 21 shows boiler wiring only
up to the burner disconnect. For additional information, refer
to manufacturer’s instructions.
1. Locate and remove boiler junction box cover.
2. Locate wire nut with yellow and black wire (if more than one
exists, pick the one with black wire going to burner harness).
Clip the wire nut.
3. Strip 1/2" from the ends of both the black and the yellow wires.
4. Clip the quick connects from the blue wires coming from the
BVSS Harness and strip 1/2" from the ends.
5. Using two wire nuts from the kit, wire the blue wires in series
with the black and yellow wires (see Figure 21).
6. Replace junction box cover.
7. Turn on power and verify safe operation of the appliance per
GO Boiler Manual.
8. Restore boiler to normal operation.
1
3
4
2
5
Connect wiring (Probe-typeLWCO)
Figure22 Boiler wiring for probe-type LWCO — see Figure 23, page 31 for component locations
Part number 550-142-330/0421
30
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
SERVICETECHNICIANONLY—readandfollowcompletely.
Connect wiring (Probe-typeLWCO) (continued)
Part number 550-142-330/0421
31
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
SERVICETECHNICIANONLY—readandfollowcompletely.
Blocked vent shutoff switch (BVSS), when
required
In Canada, a blocked vent shutoff switch kit must be
installed (see parts list page 42). See Figure 18, page 27.
When using the OVD damper kit, the BVSS is re-
quired, and is integrated into the damper harness
wiring.
When using the BVSS without the OVD damper, the
BVSS is wired directly to the junction box as follows.
The BVSS wiring diagram in Figure 24 shows boiler
wiring only up to the burner disconnect. For addi-
tional information, refer to manufacturer’s instruc-
tions.
1. Locate and remove boiler junction box cover.
2. Locate wire nut with two black wires (if more than one exists,
pick the one with black wire going to the burner harness).
Clip the wire nut.
3. Strip 1/2" from the end of both the black wires.
4. Clip the quick connects from the blue wires coming from the
BVSS Harness and strip 1/2" from the ends.
5. Using two wire nuts from the kit, connect the blue wires in series
with the two black wires (see Figure 24).
6. Replace junction box cover.
7. Turn on power and verify safe operation of the appliance.
8. Restore boiler to normal operation.
Figure23 Boiler wiring for probe-type LWCO —
component locations for wiring diagram,
Figure 22, page 30
1 Pressure control wiring harness
2 Tankless heater control wiring
3 Burner disconnect plug
4 Burner wiring harness
5 Low water cutoff wiring harness (not
furnished on Semi-packaged and Knocked-
down boilers).
120 VAC field wiring 120 VAC factory wiring
Figure24 BVSS wiring diagram (probe-type LWCO)
1
3
4
5
2
Part number 550-142-330/0421
32
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
SERVICETECHNICIANONLY—readandfollowcompletely.
General oil piping requirements
Location and installation of oil tanks, oil piping and burners must follow:
•NFPA 31 - latest edition, Standard for the Installation of Oil-
Burning Equipment.
•In Canada, CSA B139, Installation of Oil-Burning Equipment.
•Local codes and regulations.
• Information provided with burner and fuel pump.
•If any part of fuel oil tank is above level of burner, installation of an
anti-siphon device is highly recommended to prevent flow of oil in
case of oil line break.
•Support oil lines as required by codes.
•Make tank connections with swing joints or copper tubing to prevent
breaking in case the tank settles. Make swing joints so they will tighten
as tank settles. Non-hardening pipe joint compounds should be used on
all threads.
Do not use Teflon tape as an oil pipe sealant. It can cause valves
to fail, creating hazards. Do not use compression fittings, only
flare fittings.
•Underground pipe must be run in a casing to prevent oil leaking into
ground or under floor. Check local codes for information.
Oil piping connection at burner
See Figure 25 for recommended connection at burner, allowing burner
mounting door to swing open completely for servicing.
Figure25 Recommended oil piping connection to burner
OVD-Vent damper wiring
Connect oil piping
Vent damper wiring
1. Boiler models SGO-3 through SGO-7 require the
installation of the Field Controls OVD-7 damper,
Weil-McLain part number 381-800-515. The
damper is included with Packaged SGO-3 to SGO-6
boilers, and is sold separately for Semi-packaged
and Knocked-down boilers.
2. When installing the boiler, wire all controls from
vent damper and thermal switch in accordance
with the OVD damper instruction sheet, which is
provided with the damper.
3. Connect damper wires to the burner by splicing the
burner wires as shown in the appropriate wiring di-
agram. See Figure 19, page 28 or Figure 22, page 30.
Part number 550-142-330/0421
33
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
SERVICETECHNICIANONLY—readandfollowcompletely.
Start up –
Steam Boiler Water Treatment
Steam Heating Installation Considerations
Closed steam heating systems should not have high amounts
of make-up water. Make-up water only occurs when the system
is leaking or when make-up water is incorrectly administered.
And, even with chemical treatment, make-up water will reduce
boiler life due to corrosion. And chemical treatment may be dif-
ficult to execute if the system make-up volume is unpredictable.
Troubleshoot the system BEFORE considering water treatment.
If the system is using make-up water, then the following may be
likely:
•Leakingreturnlines, underground pipes, faulty steam traps,
faulty air vents
•Automaticwaterfeedisinstalledincorrectlyorincorrectly
adjusted
•Ifthesystemutilizesacondensatereceiver,thefeedermay
be flooding due to long system time lag.
If the piping is NOT leaking, consider installing a boiler feed
system (NOT a condensate return system). The boiler feed
system provides condensate storage and allows the boiler to
directly control water level. This is not the case with gravity
return systems or condensate return systems — these only
provide water to the boiler when the condensate returns from
the system. If the system time lag is longer than boiler can
provide steam, and the boiler is equipped with an automatic
feeder, water will feed to the boiler before the condensate can
return from the system. This will cause overfill and flooding
when the condensate does return. Also, pumping cold make-up
water directly into the boiler collapses the water level, causing
false indications of need for make-up. With a boiler feed system,
the float control on the boiler turns the feed pump on and off as
needed. Make-up water is added at the boiler feed system tank.
And the storage volume of the tank makes it unlikely that make-
up will be needed UNLESS there is a system leak.
Chlorides
Over the last several decades, the level of chlorides in some
ground water and city water supplies have increased due to
use of salt during the removal of snow and ice from roads and
highways, and the increased use of water softeners. Elevated
levels of chlorides (over 200 ppm) in the water of steam boilers
will accelerate water side corrosion and shorten the operating
life of the boiler.
Chlorides and other dissolved solids are present in boiler make-
up water and are not removed from the boiler when the boiler
is producing steam. The level of chlorides and dissolved solids
in the boiler water increase when make-up water is added to the
boiler because of normal maintenance to low water cutoffs and
system leaks. If there are high chloride and dissolved solid levels
in boiler make-up water, boiler water treatment should be con-
sidered.
In general, cast iron steam boilers do not require water treatment
for protection. However, some boiler water treatment chemi-
cals can promote water level instability. Surging and priming in
steam boilers can result even though the boiler was thoroughly
cleaned before the treatment was added.
Systems where treatment should be
considered are:
•Processapplications
•Contaminatedcondensate
•Largemake-upwaterrequirements
•Systemcomponentsrequiringcorrosioninhibitor
•Extremelyhardwater
•Make-upwatersupplywithhigherthan30ppmofchloride
Beware the Foam
Water treatment chemicals should be thoroughly reviewed be-
fore they are introduced into the boiler and heating system. Of
particular concern are foaming agents that will interfere with
the disengagement of the steam at the boiler waterline. For this
reason, foaming agents cannot be tolerated in steam boilers.
Testing & Treatments
To test the boiler water treatment chemicals, prepare a small
amount of the chemical intended for the boiler with water. In a
ventilated area, put this mixture into a pan and bring to a “roll-
ing boil” on the stove. If the mixture foams, it is not suitable
for the boiler.
Recognized treatment compounds used for oxygen scaveng-
ing and corrosion protection should not affect the life of the
elastomer sealing rings. Asking the treatment supplier to test
a sealing ring in the proposed compound can eliminate any
doubt. In any case, a compound containing petroleum should
not be used.
Without Chemical Treatment
•When the chloride level is above 400 ppm, or the total dis-
solved solids (TDS) are above 1000 ppm, drain and refill the
boiler with fresh water and bring the boiler to pressure for
15 minutes per the boiler manual to drive off excess oxygen.
•If chemical treatment is not used and chloride level and
TDS levels are not monitored, drain and refill the boiler
when the chloride level is above 400 ppm, or the total dis-
solved solids (TDS) are above 1000 ppm. After refilling the
boiler, bring the boiler to pressure for 15 minutes per the
boiler manual to drive off excess oxygen.
These steps will help prevent corrosion caused by high conductivity,
but may not prevent under-deposit corrosion.
In general, cast iron steam boilers do not require water treatment
for protection. However, some water conditions may require
the boiler be drained and refilled, or in more aggressive areas,
chemically treated.
Part number 550-142-330/0421
34
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
SERVICETECHNICIANONLY—readandfollowcompletely.
Fill the system
1. Do not fill (except for leakage tests) until boiler is
ready to be fired.
2. Fill to normal water line as indicated on jacket
front panel.
3. Boiler water pH 7.0 to 8.5 is recommended.
Failure to maintain recommended pH
level can cause section failure and leaks.
4. Follow “Skim steam boiler” to assure proper op-
eration.
Tips for steam systems
•Check boiler and system piping for leaks. Continual
makeup water will reduce boiler life. Minerals can
build up in sections, reducing heat transfer and caus-
ing cast iron to overheat, resulting in section failure.
Failure to maintain recommended pH
and repair leaks can cause section iron
corrosion, leading to section failure and
leaks. Do not use petroleum-based seal-
ing or stop-leak compounds in boiler
system. Damage to system components
can result.
•For pH conditions outside 7.0 to 8.5 range or un-
usually hard water areas (above 7 grains hardness),
consult local water treatment company.
Skim steam boiler
Clean new steam boilers to remove any
impurities. Failure to properly clean can
result in violent water level fluctuations,
water passing into steam mains, or high
maintenance costs on strainers, traps or
vents. Skim boiler only. Do not clean old
piping or leaks can occur.
Do not use petroleum-based compounds
in boiler system. Damage to system
components can result, causing property
damage.
1. Provide 1½" skim piping from skim tapping
to floor drain. Add a tee in piping to observe
skim water level. Raise waterline to midpoint of
skim tapping.
2. Fire burner to maintain water temperature below
steaming temperature during skimming process.
3. Feed in water to maintain water level. Cycle burner
to prevent rise in steam pressure. Continue skim-
ming until discharge is clear.
4. While boiler is warm, but not hot, drain boiler
through drain valve.
5. Remove skim piping. Close drain valve. Fill with
fresh water to normal waterline. Start burner and
steam for 15 minutes to remove dissolved gases.
Stop burner.
6. Check traps and air vents for proper operation.
7. Process may need to be repeated after several weeks
of operation.
To place in operation
Follow information below to prevent se-
vere personal injury, death or substantial
property damage:
•Donotusecrankcasedrainingsoranyoil
containing gasoline. See burner manual
for proper fuel oil.
•Donotattempttostartburnerwhen
excess oil has accumulated in combustion
chamber, when unit is full of vapor, or
when combustion chamber is very hot.
•Donotstartburnerunlesscollectorhood,
breeching and burner mounting door are
secured in place. Never burn garbage or
paper in the boiler.
•Neverleavecombustiblematerialaround
boiler
1. Verify boiler is filled with water to normal waterline
as indicated on jacket front panel.
2. Open burner door and verify rear target wall, floor
and burner door insulations are in proper position
and condition.
3. Verify burner mounting door is closed tightly and
burner wiring harness is connected to junction box.
4. Factory burner adjustment and settings may not
be suitable for specific job conditions. See “Burner
adjustments” on page 37.
A burner nozzle change may be required -
refer to the burner instructions or boiler’s
rating label for correct selection.
Make final burner adjustments using
combustion test equipment to assure
proper operation. Do not fire boiler
without water. Sections will overheat,
damaging boiler and resulting in sub-
stantial property damage.
5. Check boiler and system piping for leaks. See “Tips
for steam systems.”
6. Inspect breeching and venting for proper operation.
Start up (continued)
Part number 550-142-330/0421
35
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
SERVICETECHNICIANONLY—readandfollowcompletely.
Check off Steps as completed
❏
Boiler properly filled with water?
❏
Boiler piping checked for leaks (including tankless heater, if used)?
❏
System vents operating properly?
❏
Boiler properly skimmed?
❏
Air purged from oil piping? Piping checked for leaks?
❏
Flue cap in place and tightened? Burner door closed, sealed and nut tight? Burner plugged in and service switch on?
Obtain gas-tight seal to prevent possible flue gas leakage and carbon monoxide emissions, leading to severe personal
injury or death.
❏
Proper draft and burner flame? Final adjustment made with combustion test equipment?
❏
Test pressure control: While burner is operating, move indicator on limit control below actual boiler steam pressure. Burner
should go off. Raise setting on pressure control above steam pressure and burner should re-ignite.
❏
Test low water cutoff(s): Follow control manufacturer’s instructions for testing procedures. Make sure burner goes off when
control responds to low water condition. Burner should re-ignite when proper water level is restored.
❏
Test additional field-installed controls: If boiler has additional operating control or other controls, test for operation as outlined
by control manufacturer. Burner should be operating and should go off when controls are tested. When controls are restored,
burner should re-ignite.
❏
Limit control set to system pressure requirements?
❏
Thermostat heat anticipator setting (if available) set properly? Refer to “Connect wiring,” page 26.
❏
Boiler cycled with thermostat? Raise to highest setting and verify boiler goes through normal start-up cycle. Lower to lowest set-
ting and verify boiler goes off.
❏
Observed several operating cycles for proper operation?
❏
Set room thermostat(s) to desired room temperature?
❏
Completed Installation and Service Certificate?
❏
Reviewed Maintenance and Service Manual with owner or maintenance person and instructed person to keep for future reference?
❏
Returned all instructions provided with boiler to its envelope and placed with boiler for future reference?
Check out procedure
Installation and service certificate
Date Installed: __________________ _________
Boiler Model Number: _______ Series: __________
Consumer Protection (CP) Number(s):
Measured Btu or GPH Input: _______________
❏
Installation instructions have been followed.
❏
Check-out procedure has been performed.
❏
Above information is certified to be correct.
❏
Information received and left with owner/
maintenance person.
Installation and service certificate
Installer: ________________________________________________________________________________________________
(Company) (Address) (Phone)
_________________________________________
(Installer’s Signature
Part number 550-142-330/0421
36
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
SERVICETECHNICIANONLY—readandfollowcompletely.
Annual service check list
Annual Service Call
Checklist
(follow in order listed below)
Dates Comments
1
Check that boiler area is free from
combustible materials, gasoline and
other flammable vapors and liquids.
2
Check for and remove any obstruction
to combustion and ventilation air flow
to boiler.
3
Check breeching and chimney or vent
for obstructions, damage, etc. Repair
or replace as necessary.
4
Clean boiler ue ways. See page38.
5
Perform service on low water cuto,
relief valve and gauge glass. See
page37.
6
Check boiler and piping for leaks and
repair if found.
7
Inspect and adjust burner. See burner
manual and:
•change nozzle.
•check ignition electrode settings.
•clean blower housing and wheel.
•make sure blower wheel turns
freely.
•oil burner motor if required.
•clean air inlet.
•clean or change fuel lter and
strainer.
8
Make sure boiler is lled with water.
See page34
.
9
Start unit and verify combustion
settings with combustion test
equipment. See page34.
10
Verify operation of all controls on
boiler. See page34.
Any parts of the boiler furnished by Weil-McLain must be replaced by parts listed in
Weil-McLain Boiler and Repair Parts Book.
Part number 550-142-330/0421
37
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
SERVICETECHNICIANONLY—readandfollowcompletely.
General description of control operation
Low water cutoff
Shuts down boiler if there is a low water condition.
Steam relief valve
Provides discharge if boiler pressure exceeds 15 psig.
Pressure limit control
If high steam pressure occurs, control shuts down burners until
pressure drops. Limit should be set higher than design pressure
of system. Operating control can be set at 5 psig and adjusted
to comfort level. Normal operation is usually less than 5 psig. At
certain times the system may operate under vacuum conditions.
Gauge glass
Indicates boiler water level. Cold fill water level should correspond
to line stamped on boiler jacket. When boiler operates, water
level will fluctuate.
Pressure gauge
Provides reading of boiler pressure. Maximum boiler pressure
is 15 psig.
Tankless water heater
Weil-McLain tankless heater ratings are based on 200°F boiler
water temperature. To get rated output, set tankless heater con-
trol to 200°F. Control can be adjusted to meet system hot water
requirements.
Burner adjustments
A burner nozzle change may be required - refer to
the burner instructions or boiler’s rating label for
correct selection.
Final burner adjustments must be made using com-
bustion test equipment to assure proper operation.
Do not fire boiler without water or sections will
overheat.
1. Refer to burner manual for start-up.
2. Allow boiler to heat to design condition.
3. Burner should be adjusted to 13% CO
2
or less with a smoke
level of zero and over-fire of -0.01” to -0.02”. Re-adjust burner
combustion to account for environmental conditions. Actual
CO
2
value will vary and should be adjusted for clean and safe
combustion operation. Seasonal variations as well as suf-
ficient combustion air supply can affect proper combustion
and boiler performance. The burner should only be adjusted
by a service professional with appropriate instrumentation.
Controls requiring annual service
Float-type low water cutoff
Follow instructions to blow down cutoff on page 20. Also refer
to instructions from cutoff manufacturer in envelope assembly
provided with boiler.
Probe-type low water cutoff
Cutoff must be removed and inspected and cleaned annually.
Refer to cutoff manufacturer’s instructions in envelope assembly
provided with boiler.
Steam relief valve
Check operation of steam relief valve. Follow instructions on
label fastened to relief valve.
Scald potential. Do not check operation of relief
valve unless discharge piping has been installed ac-
cording to Boiler Manual. If piping is not in place,
a qualified service technician must properly install
piping.
Gauge Glass
To clean glass:
1. Close lower gauge glass cock and carefully open petcock be-
low glass to blow water and sediment out of glass by steam
pressure.
2. Slowly open lower gauge glass cock and allow a small amount
of water to flush out through the open petcock.
3. Close petcock and fully open lower gauge cock. The water
level should immediately rise to its proper level.
4. If gauge glass breaks, close off both gauge cocks and loosen
glass retaining nuts to remove gauge glass. Do not use thin
glass tubing as a replacement.
Service and maintenance
Figure26 Thoroughly clean flue ways between all
pins at all angles. Start on top of boiler,
finish from the bottom.
Part number 550-142-330/0421
38
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
SERVICETECHNICIANONLY—readandfollowcompletely.
Cleaning boiler flue ways
The boiler contains ceramic fiber and fiberglass materials.
Use care when handling these materials per instructions
on page 48 of this manual. This boiler contains ceramic
fiber and fiberglass materials that have been identified
as carcinogenic, or possibly carcinogenic, to humans).
Failure to comply could result in severe personal injury.
Make sure all electrical connections to boiler are turned
off and wait until boiler is warm, not hot, before clean-
ing. Failure to do so will result in severe personal injury,
death or substantial property damage.
1. Top flue boilers -remove breeching and jacket top panel. Rear flue
boilers - remove jacket top panel.
2. Remove flue collector hood, saving hardware for reassembly.
3. Shut off oil valves. Arrange drip pans under the areas of oil piping
that will be disconnected. Disconnect oil line at burner so that you
can swing open the door completely.
4. Line combustion chamber floor with newspaper to catch any soot
that will be loosened in the cleaning process.
5. Starting at the top of the boiler, use a wire flue brush to thoroughly
clean between all pins at all angles. Be careful not to damage side
wall of rear refractory.
6. Move to the bottom of the flue ways and clean up between the
sections to reach pins left uncleaned in Step #5.
7. Once the flue ways are cleaned, carefully remove the paper from
the floor of the combustion chamber.
8. Verify sealing rope around flue area is intact. Visually check condi-
tion and position of insulation in combustion chamber floor, and
the refractories at the rear of boiler and in the burner mounting
door. Replace any parts as necessary.
9. Close burner mounting door and tighten nut securely. Place flue
collector hood on top of boiler. Secure with hardware from Step #2.
Maintain a gas-tight seal to avoid possible flue gas leak-
age and carbon monoxide emissions, which can lead to
severe personal injury or death.
Reported problems
Inspect any problems reported by owner and correct before
proceeding.
Boiler area
1. Verify that boiler area is free of any combustible materials,
gasoline and other flammable vapors and liquids.
2. Verify that boiler area is free of any of the contaminants listed
in Table 2 on page 10 of this manual. If any of these are pres-
ent in the boiler intake air vicinity, they must be removed. If
they cannot be removed, install combustion air piping to the
boiler in accordance with national, provincial or local codes.
❏ Inspect . . . . . . . . . .
Piping
1. Check the boiler interior piping and all system piping for
signs of leaks.
2. Repair any leaks before proceeding.
Do not use petroleum-based cleaning or sealing
compounds in boiler system. Severe damage to
boiler will occur, resulting in substantial property
damage.
Eliminate all system or boiler leaks. Continual fresh
makeup water will reduce boiler life. Minerals can
build up in sections, reducing heat transfer, over-
heating cast iron, and causing section failure. Leak-
ing water may also cause severe property damage.
10. Check breeching for sooting and clean if necessary.
Install jacket top panel and breeching.
11. Reconnect oil line and all electrical connections.
Wear a NIOSH -certified dust respirator (N95)
while cleaning the boiler, per WARNING on
page 48. Failure to comply could result in
severe personal injury.
Service and maintenance (continued)
Part number 550-142-330/0421
39
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
SERVICETECHNICIANONLY—readandfollowcompletely.
❏ Service. . . . . . . . . .
Gaugeglass
Normal waterline is halfway up gauge glass. Clean when needed.
1. Close lower gauge cock.
2. Open pet cock.
3. Open lower gauge cock and allow a small amount of water to
flush out through open pet cock.
4. Close pet cock.
5. Open lower gauge cock.
Boiler pressure must be low to eliminate potential
of severe burns.
If gauge glass breaks, close both gauge cocks. Replace
gauge glass. Do not replace with thin glass tubing.
Failure to comply could cause severe personal injury,
death or substantial property damage.
❏ Check/test. . . . . . . . . .
Boilerwaterline
Normal waterline is halfway up gauge glass.
Limitcontrols
Inspect and test the boiler limit control. Verify operation by turn-
ing control set point below boiler pressure. Boiler should cycle off.
Return dial to original setting.
Lowwatercutoffs
Probe-type low water cutoff (see below)
Clean and test probe-type low water cutoff for proper operation.
Remove, inspect and clean the low water cutoff at least annually
before testing. Refer to low water cutoff manufacturer’s instruc-
tions in envelope assembly provided with boiler.
1. Turn off power to boiler and wait 5 minutes.
2. Drain water to bottom of gauge glass.
3. Turn on power.
4. Set thermostat to call for heat. Red neon lamp on lower water
cutoff should light.
5. Wait 5 minutes. Boiler should not fire.
6. Refill boiler to correct waterline. Red lamp should go off.
7. Wait 5 minutes. Boiler should fire.
8. Return thermostat to normal setting.
❏ Check/test. . . . . . . . . .
Float-type low water cutoff (when provided by others
— see below)
Clean and test float-type low water cutoff (when provided by
others) to clear float chamber of sediment.
1. Open blow down valve at bottom control.
2. Drain water into a bucket.
Scald potential. Boiler pressure must be low to avoid
the potential of severe burns from steam.
3. Check float-type low water cutoff for proper operation:
a. Turn operating control to call for heat.
b. Before water gets hot, drain to bottom of gauge glass.
Boiler should shut off after water level lowers a few inches.
c. Refill boiler to correct waterline. Boiler should come back on.
❏ Check monthly
Venting system
Visually inspect all parts or the flue gas venting system for
any signs of blockage, leakage or joints or deterioration of the
piping. Notify your qualified service technician at once if you
find any problem.
Failure to inspect the vent system as noted above and
have it repaired by a qualified service technician can
result in vent system failure, causing severe personal
injury or death.
Service and maintenance (continued)
Part number 550-142-330/0421
40
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
SERVICETECHNICIANONLY—readandfollowcompletely.
Annual service
Boiler relief valve
After following the warning directions below, if the relief valve weeps or
will not seat properly, replace the relief valve.
Before testing, make certain discharge
pipe is properly connected to valve
outlet and arranged to contain and
safely dispose of boiler discharge. Wear
gloves to protect your hands from hot
surfaces. Verify that discharge piping
is installed in accordance with this
manual and the instructions on the
relief valve tag. Failure to comply will
expose operator and others to severe
personal injury or death.
Safety relief valves should be reinspected AT LEAST ONCE
EVERY THREE YEARS, by a licensed plumbing contractor or
authorized inspection agency, to ensure that the product has
not been affected by corrosive water conditions and to ensure
that the valve and discharge line have not been altered or
tampered with illegally. Certain naturally occurring conditions
may corrode the valve or its components over time, rendering
the valve inoperative. Such conditions are not detectable
unless the valve and its components are physically removed
and inspected. This inspection must only be conducted by a
plumbing contractor or authorized inspection agency — not by
the owner. Failure to reinspect the boiler relief valve as directed
could result in unsafe pressure buildup, which can result in
severe personal injury, death or substantial property damage.
Check the setting of the boiler limit control. The control
should never be set with a pressure above 10 psig. Operating
at a higher pressure can cause damage to the boiler relief valve.
The boiler relief valve must be tested at least monthly during
the heating season to verify the valve and discharge piping
flow freely.
Inspect the boiler relief valve and the relief valve discharge
pipe for signs of weeping or leakage.
If the relief valve often weeps, the expansion tank may not be
working properly.
• Immediately contact your qualified service technician to
inspect the boiler and system.
If corrosion and/or deposits are noticed within the valve body,
testing must be performed more often. A “try lever test” must
also be performed at the end of any non-service period. Follow
the instructions below for a “try lever test”:
• With the system at operating pressure, lift and hold the
test lever fully open for at least 5 seconds to flush the valve
seat free of sediment and debris. Then release lever and
permit the valve to snap shut.
Review with owner
1. Review the Homeowner’s Information, pages 2
through 7 with the owner.
2. Emphasize the need to perform the maintenance
schedule specified on page 5.
3. Remind the homeowner of the need to call in a
licensed contractor should the boiler or system
exhibit any unusual behavior.
4. Remind the homeowner to follow the proper shut-
down procedure and to schedule an annual start-
up at the beginning of the next heating season.
Service and maintenance (continued)
Boiler and system piping
Visually inspect for leaks around piping, circulators,
relief valve and other fittings. Check oil lines and
boiler air for signs of oil leakage. Immediately call a
qualified service technician to repair any leaks.
Have leaks fixed at once by a qualified
service technician. Continual fresh
makeup water will reduce boiler life.
Minerals can build up in sections,
reducing heat transfer, overheating cast
iron, and causing section failure.
Do not use petroleum-based cleaning
or sealing compounds in boiler system.
Severe damage to boiler and system
components can occur, resulting in
possible severe personal injury, death or
substantial property damage.
Part number 550-142-330/0421
41
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
SERVICETECHNICIANONLY—readandfollowcompletely.
Figure27 SGO Series 4 boiler jacket
Replacement parts
Model
Jacketpanelwith
insulation—front
LeftsideandrearRightsideandrearToppanelwithcap
SGO-3 381-355-928 381-355-929 381-355-974 381-355-933
SGO-4 381-355-928 381-355-930 381-355-975 381-355-934
SGO-5 381-355-928 381-355-931 381-355-976 381-355-935
SGO-6 381-355-928 381-355-932 381-355-977 381-355-936
CompleteJacketcartons
3 section 416-700-453
4 section 416-700-454
5 section 416-700-455
6 section 416-700-456
7 section 416-700-457
8 section 416-700-458
9 section 416-700-459
Commonjacketpartsforallboilers
Plastic ue cap cover w/insulation 560-917-105
Jacket hardware kit 386-700-853
Touch up paint, Cloud spray can 381-359-278
Touch up paint, Slate spray can 384-000-141
Figure28 SGO Series 4 section and flue collector parts
Part number 550-142-330/0421
42
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
SERVICETECHNICIANONLY—readandfollowcompletely.
Replacement parts
ItemDescription
Part
Number
A Wide front section (7021) 316-700-245
B
Regular intermediate section
(7015)
316-700-065
C
Intermediate section w/draw rod
lugs (7016)
316-700-070
D
Back section w/7" ue, supply & 2"
return (7027)
316-700-227
E
Section replacement kit (for 1 joint,
includes seals, rope, adhesive and
collector hood hardware) front or
back section
386-700-852
Section replacement kit (for 2
joints, includes seals, rope and
adhesive) intermediate section
386-700-851
Section assembly, for SGO-3
w/jacket & collector hood installed
386-701-008
Section assembly, for SGO-4
w/jacket & collector hood installed
386-701-009
Section assembly, for SGO-5
w/jacket & collector hood installed
386-701-010
Section assembly, for SGO-6
w/jacket & collector hood installed
386-701-011
Section assembly only, for SGO-3 386-700-969
Section assembly only, for SGO-4 386-700-970
Section assembly only, for SGO-5 386-700-971
Section assembly only, for SGO-6 386-700-972
Section assembly only, for SGO-7 386-700-669
Section assembly only, for SGO-8 386-700-670
Section assembly only, for SGO-9 386-700-671
F Collector hood kit for SGO-3* 386-700-340
F Collector hood kit for SGO-4* 386-700-341
F Collector hood kit for SGO-5* 386-700-342
F Collector hood kit for SGO-6* 386-700-343
F Collector hood kit for SGO-7* 450-020-191
F Collector hood kit for SGO-8* 450-020-192
F Collector hood kit for SGO-9* 450-020-193
ItemDescription
Part
Number
G Tie rod 1/2 x 5
1/2 (SGO-7, 8, 9) 560-234-464
G Tie rod 1/2 x 103/4 (SGO-7) 560-234-491
G Tie rod 1/2 x 121/4 (SGO-3) 560-234-493
G Tie rod 1/2 x 133/8 (SGO-7 & 8) 560-234-494
G Tie rod 1/2 x 14 (SGO-8, 9) 560-234-470
G Tie rod 1/2 x 15 (SGO-9) 560-234-495
G Tie rod 1/2 x 153/8 (SGO-4) 560-234-532
G Tie rod 1/2 x 161/2 (SGO-9) 560-234-496
G Tie rod 1/2 x 181/2 (SGO-5) 560-234-475
G Tie rod 1/2 x 215/8 (SGO-6) 560-234-536
G Tie rod 1/2 x 243/4 (SGO-7) 560-234-540
G Tie rod 1/2 x 28 (SGO-8) 560-234-544
G Tie rod 1/2 x 31 (SGO-9) 560-234-546
H
Heater cover plate carton (cover
plate, gasket, studs & nuts)
389-900-103
J
Combustion chamber kit (rear &
front ref., Door refractory blanket,
rope, blanket & water glass)
386-700-355
K
Burner mounting door assembly
(door, obs. Port, rope, ins. And
pins)
386-700-358
L Door hinge (7054) 330-054-300
M Door refractory 386-700-359
N Door refractory blanket 591-222-115
P Observation port shutter 460-039-867
Q Door seal rope 5' 590-735-104
R
3/8" Glass rope for collector hood
(7' for largest size hood)
590-735-109
S
Flue cap assembly (cap, strap,
rope and screws)
386-700-344
Flue brush (123D) 591-706-214
Blocked vent shutoff switch
(Canada only)
511-624-650
* Includes ue cap assembly, rope and hardware
for installation.
Repair parts must be purchased through Weil-McLain for the specific boiler as indicated in the list - page 42.
Results from using modified or other manufactured parts will not be covered by warranty and may damage boiler
or impair operation.
D
J
K
J
J
C
G
G
N
Q
E
G
F
R
B
A
P
L
J
M
H
S
Figure29 SGO Series 4 section and flue collector parts
Part number 550-142-330/0421
43
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
SERVICETECHNICIANONLY—readandfollowcompletely.
Replacement parts (continued)
Part number 550-142-330/0421
44
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
SERVICETECHNICIANONLY—readandfollowcompletely.
Item
No.
DescriptionPartnumber
1 Syphon, 180° Bend, 1/4" brass pipe 560-640-698
2a
Steam relief valve, set to relieve at 15 PSIG., 3/4" NPT inlet
3/4" NPT side outlet, 300 lbs./hr steam capacity
511-548-023
2b
Steam relief valve, set to relieve at 15 PSIG., 3/4" NPT male inlet
3/4" NPT female side outlet, 407 lbs./hr steam capacity
3 Steam pressure gauge, 0-30 PSIG. 510-218-045
4 Gauge cock set, B15, standard stem 510-218-135
5 Gauge glass kit, includes glass, gaskets and brass washers 383-600-001
6 Water gauge glass guard, 105/8" long 563-334-597
7
High pressure limit control, operating range 0.5-9 PSI., additive differential 1-5 PSI.
510-312-135
High pressure limit control, operating range 0-15 PSI., differential 2-8 PSI.
8 High temperature limit control, spst, automatic recycle with 3/4" well (used in tankless heater kit) 510-312-209
9 Low water cutoff, oat type 511-114-495
10 Low water cutoff, probe type 511-100-007
11
Drain cock, 3/4", 11/2" shank 511-210-423
Drain cock, 3/4" 511-246-392
12 Balanced draft damper (barometric) 7" 510-512-267
13 Junction box wiring harness assembly (Semi-packaged and Knocked-down boilers only) 591-391-848
14 Junction box cover assembly with service switch 591-391-854
15 Burner harness assembly 591-391-850
16 Limit control without well, spdt (for tankless heater) 510-311-024
17 Junction box-wiring harness assembly (SGO – oat low water cutoff only - Packaged only) 591-391-842
18 Junction box-wiring harness assembly (SGO - probe low water cutoff only - Packaged only) 591-391-965
19 Flue pipe brackets (requires 2 of this item) (Not shown) 426-700-268
20
Tankless Heater - steam boiler, includes heater, gasket, nuts and studs.
For SGO-3 through 9 (Not shown)
590-921-903
21 OVD-7 Vent damper kit – Required for SGO-3 through 7 381-800-515
Replacement parts (continued)
Figure30 SGO Series 4 Trim Parts
Repair parts must be purchased through Weil-McLain for the specific boiler as indicated in the list - page 42.
Results from using modified or other manufactured parts will not be covered by warranty and may damage boiler
or impair operation.
Part number 550-142-330/0421
45
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
SERVICETECHNICIANONLY—readandfollowcompletely.
Replacement parts (continued)
Figure31 SGO Series 4 Trim Parts
Intermediate
6¼
[158.8]
7 DIA
[177.8]
R
7 DIA
[177.8]
29
9
/16
[750.9]
SGOback
Steam
supply
Skim
tapping
7¾ [196.9]
10¼ [260.4]
1⅛
[28.6]
3¾ [95.3]
4⅜ DIA
[111.1]
burner
opening
SGO“A”front
9½ [241.3]
35⅝
[904.88]
26⅞
[682.6]
Water
Line
30
1
/16
[763.6]
SGOsidewithburner
Steam supply
piping 3-9
Steam supply
piping 6-9
7
3
/16 [182.6]
4
1
/16 [103.2]
14 Approx.
7 DIA
[177.8]
A
7 DIA
[177.8]
15½
[393.7]
L
B
20¼ [514.4]
Dimensions
Part number 550-142-330/0421
46
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
SERVICETECHNICIANONLY—readandfollowcompletely.
Boilermodel
number
ABL
InchesmmInchesmmInchesmm
SGO-3
— — 13-1/2 342.9 16-7/8 428.7
SGO-4
— — 16-5/8 422.1 20 508.0
SGO-5
— — 19-7/8 504.9 22-1/8 587.2
SGO-6
19 482.6 23 584.2 26-1/4 666.7
SGO-7
22-1/8 561.8 26-1/8 663.4 29-3/8 746.2
SGO-8
25-1/4 641.4 29-1/4 742.9 32-1/2 825.5
SGO-9
28-3/8 720.9 32-3/8 822.4 35-5/8 904.7
Figure32 SGO boiler dimensions — inches (mm)
Part number 550-142-330/0421
47
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
SERVICETECHNICIANONLY—readandfollowcompletely.
AHRICertiedRating
Boiler
Model
Number
Burner
Input
Heating
Capacity
Seasonal
Efciency
Net
Ratings
Note 5
Steam
Boiler
Water
Content
Minimum
Chimney
Dimensions
Flue
Outlet
Diameter
Draft
Loss
Thru
Boiler
OVD
Damper
Required
GPH
Note 3
MBH
Note 2
MBH
Note 2
AFUE
%
Steam
Sq. Ft.
Steam
MBH
Gallons
Note 8
Rect.
In.
Round
In.
Height
Ft.
Size
Inches
Note 1 & 7
Inch
W.C.
Note 9 Yes/No
SGO-3 0.95 133 114 (10)(11) 85.0 358 86 10.7 8 x 8 6 15 7 .020 Yes
SGO-4 1.20 168 144
(10)(11) 85.0 450 108 12.5 8 x 8 6 15 7 .010 Yes
SGO-5 1.45 203 174
(10)(11) 85.0 546 131 14.2 8 x 8 7 15 7 .015 Yes
SGO-6 1.75 245 210
(10)(11) 85.0 658 158 16 8 x 8 7 15 7 .015 Yes
SGO-7 2.00 280 240
(10)(11) 85.0 758 182 17.7 8 x 8 8 15 7 .015 Yes
SGO-8 2.30 322 266
(4)(6) — 833 200 19.4 8 x 12 8 20 7 .025 ---
SGO-9 2.55 357 295
(4)(6) — 921 221 21.2 8 x 12 8 20 7 .030 ---
NOTES:
1.
SGO boiler designed with convertible vertical and horizontal ue outlet.
2. MBH refers to thousands of Btu per hour.
3. Based on 140,000 Btu/gal.
4. Based on standard test procedures prescribed by the United States Department of Energy at combustion condition of
13.5% CO
2
and -0.02” W.C. draft over re .
5. Net ratings are based on net installed radiation of sufcient quantity for the requirements of the building and nothing need
be added for normal piping and pick-up. Steam ratings are based on a piping and pick-up allowance of 1.33. An additional
allowance should be made for unusual piping and pick-up loads. Consult local Weil-McLain Sales Ofce.
6. Gross output
7. See page 18 for minimum breeching diameter.
8. To water line.
9. Listed draft losses are for factory-shipped settings.
10. Based on standard test procedures prescribed by the United States Department of Energy at combustion of 13.0% CO
2
and -0.02” W.C. draft over re.
11. Installation of OVD Automatic Vent Damper (P/N 381-800-515) is required.
Note: A burner nozzle change may be required - refer to the burner instructions or boiler’s rating label for correct selection.
Ratings
Figure33 SGO steam boiler ratings
DOE
®
Part number 550-142-330/0421
SGO
OIL-FIRED NATURAL DRAFT STEAM BOILER — SERIES 4 — Boiler Manual
REMOVAL OF COMBUSTION CHAMBER
LINING OR BASE PANELS
The combustion chamber lining or base insu-
lation panels in this product contain ceramic
fiber materials
that have been identified as car-
cinogenic, or possibly carcinogenic, to humans
.
Ceramic fibers can be converted to cristobalite
in very high temperature applications. The
International Agency for Research on Cancer
(IARC) has concluded, “Crystalline silica
inhaled in the form of quartz or cristobalite
from occupational sources is carcinogenic to
humans (Group 1).”:
Precautionary measures
❏ Avoid breathing fiberglass dust and contact with
skin or eyes.
•Use NIOSH certified dust respirator (N95).
This type of respirator is based on the
OSHA requirements for fiberglass wool at the
time this document was written. Other types
of respirators may be needed depending on
the job site conditions. Current NIOSH recom-
mendations can be found on the NIOSH web
site at http://www.cdc.gov/niosh/homepage.
html. NIOSH approved respirators, manufac-
turers, and phone numbers are also listed on
this web site.
•Wear long-sleeved, loose fitting clothing, gloves,
and eye protection.
❏ Apply enough water to the combustion chamber
lining or base insulation to prevent airborne dust.
❏ Remove combustion chamber lining or base insula-
tion from the boiler and place it in a plastic bag for
disposal.
❏ Wash potentially contaminated clothes separately
from other clothing. Rinse clothes washer thor-
oughly.
NIOSH stated First Aid
❏ Eye: Irrigate immediately
❏ Breathing: Fresh air
REMOVAL OF FIBERGLASS WOOL
or
INSTALLATION OF FIBERGLASS WOOL
OR BASE PANELS:
This product contains fiberglass jacket insula-
tion and ceramic fiber materials in combus-
tion chamber lining or base panels in gas fired
products. Airborne fibers from these materials
have been listed by the State of California as a
possible cause of cancer through inhalation.
Precautionary measures
❏ Avoid breathing fiberglass dust and contact with
skin or eyes.
•Use NIOSH certified dust respirator (N95).
This type of respirator is based on the
OSHA requirements for fiberglass wool at the
time this document was written. Other types
of respirators may be needed depending on
the job site conditions. Current NIOSH recom-
mendations can be found on the NIOSH web
site at http://www.cdc.gov/niosh/homepage.
html. NIOSH approved respirators, manu-
facturers, and phone numbers are also listed
on this web site.
•Wear long-sleeved, loose fitting clothing, gloves,
and eye protection.
❏ Operations such as sawing, blowing, tear out, and
spraying may generate airborne fiber concentration
requiring additional protection.
❏ Wash potentially contaminated clothes separately
from other clothing. Rinse clothes washer thor-
oughly.
NIOSH stated First Aid
❏ Eye: Irrigate immediately
❏ Breathing: Fresh air
Handling ceramic fiber and fiberglass materials
