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Part number 550-100-400/0119
84
®
Series 4
gas-fired water boiler — Boiler Manual
Special considerations
Tight construction
ANSI Z223.1 defi nes unusually tight construction where:
1. Walls and ceilings exposed to the outside atmosphere have
a continuous water vapor retarder with a rating of 1 perm
or less with openings gasketed, and . . .
2. Weather-stripping has been added on openable windows
and doors, and . . .
3. Caulking or sealants are applied to areas such as joints
around windows and door frames, between sole plates and
fl oors, between wall-ceiling joints, between wall panels, at
penetrations for plumbing, electrical, and gas lines, and in
other openings.
For buildings with such construction, provide air openings
into the building from outside, sized per the appropriate case
in Figure 96, page 85 if appliances are to use inside air for com-
bustion and ventilation.
Exhaust fans and air movers
The appliance space must never be under a negative pressure
unless all appliances are installed as direct vent. Always provide
air openings sized not only to the dimensions required for the
fi ring rate of all appliances, but also to handle the air move-
ment rate of the exhaust fans or air movers using air from the
building or space.
Motorized air dampers
If the air openings are fi tted with motorized dampers, electrically
interlock the damper to:
Prevent the boiler from fi ring if the damper is not fully open.
Shut the boiler down should the damper close during boiler
operation.
To accomplish this interlock, wire an
isolated contact (proving
the damper open) in series with the thermostat input to the
boiler. The boiler will not start if this contact is open, and will
shut down should it open during operation.
Combustion air provision
The Ultra boiler can use inside air if no contaminants are pres-
ent in the boiler space. (If contaminants are likely to be present,
install the boiler as a direct vent appliance, using the appropriate
vent instructions in this manual.)
The boiler room must be fi tted with combustion air openings
large enough to provide air for all appliances in the room. Use the
following information to size the openings. Ensure the installation
complies with all applicable codes and standards.
Sizing combustion air openings
Air openings provide for ventilation (as well as combustion air)
to prevent overheating of the boiler controls and boiler space.
Air is also needed for other appliances located in the same space.
Use Figure 96, page 85 , selecting the appropriate installation
conditions.
Air openings must be sized to handle all appliances
and air movers (exhaust fans, etc.) using the air
supply.
The sizing given in Figure 96, page 85 is based on the National
Fuel Gas Code, ANSI Z223.1, allowing adequate air openings for
gravity-vented gas appliances (Category I) in addition to that
needed for the Ultra boiler.
The air openings recommended in Figure 96, page 85 will allow
adequate ventilation and combustion air provided the boiler
room is not subjected to negative pressure due to exhaust fans
or other mechanical ventilation devices.
Refer to the National Fuel Gas Code for dealing with other
conditions.
Free area — louver allowance
The free area of openings means the area after reduction for any
installed louvers or grilles
. Be sure to consider this reduction when
sizing the air openings.
DIRECT EXHAUS T — Boiler room air openings
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