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Part number 550-100-325/0419
39
AquaBalance
®
Series 2 Wall Mount Gas-fired Water Boiler – Boiler Manual
Figure 49
18 Primary/Secondary System Piping
System water piping methods
Using primary/secondary piping will provide the most efficient
and reliable operation of the boiler and the heating system.
1. Use information beginning on page 35 to size pump for
proper flow through the boiler.
2. Reference suggested piping layouts on pages 40-45.
System water piping methods
1. Connect boiler to system only as shown in Figure 51, page 40.
The primary/secondary piping shown ensures the boiler
loop will have sufficient flow.
2. Install a system circulator or zone circulators as shown in the
piping diagrams in the Primary/Secondary System Piping
section in this manual. These circulators must be supplied
by the installer.
1. Size circulators based on the flow rate required to achieve the
temperature drop required. You can closely estimate temper-
ature rise (or drop) through a circuit by using the following
formula, where TD is temperature rise (or drop), FLOW is
flow rate (in gpm), and BTUH is the heat load for the circuit:
=
BTUH
TD x 500
:
1. Consider a system loop for a system with total heating load
equal to 143,000 Btuh. The desired temperature drop through
the system piping is 20°F. Then the required flow rate is:
=
20 x 500
=
1. The circulator must be capable of delivering the required
flow against the head loss that will occur in the piping.
2. Determine the pipe size needed and the resultant head
loss using accepted engineering methods.
Expansion Tank Location
Figure 51, page 40 show typical installation of the system expansion
tank. It is highly recommended that you locate the air separator
and expansion tank as shown in the suggested piping drawings
on pages 39 - 41.
Ensure that the expansion tank size will handle boiler and system
water volume and temperature. See tank manufacturer’s instruc-
tions and ratings for details. Additional tanks may be added to the
system if needed to handle the expansion. These tanks may be
installed by connecting to tees in the system piping.
Undersized expansion tanks cause system water to
be lost from the relief valve and makeup water to be
added through the fill valve. Eventual boiler failure
can result due to excessive make-up water addition.
Always locate the cold-water fill connection at the
expansion tank. Never locate this elsewhere.
Diaphragm- or bladder-type tank:
Refer to Figure 51, page 40 for suggested piping when using a
diaphragm- or bladder-type expansion tank.
Diaphragm- or bladder-type expansion tank—
Always check pressure and charge tank with tank
removed from system to be sure reading is accurate.
Boiler relief valve is set for 30 PSIG. Operating pres-
sure of system, after temperature expansion above
cold fill pressure, should not exceed 24 PSIG to avoid
weeping of relief valve.
Install an automatic air vent on top of the air separator, per separa-
tor manufacturer’s instructions.
Automatic air vents
1. Remove the cap from any automatic air vent in the system
and check operation by depressing valve “B” slightly with the
tip of a screwdriver.
— Water from air vent may be very
hot. Avoid contact to prevent possible severe per-
sonal injury.
2. If the air vent valve appears to be working freely and not leak-
ing, replace cap “A”, twisting all the way on.
3. Loosen cap “A” one turn to allow vent to operate.
4. Have vent replaced if it does not operate correctly.
Figure 50
85036
A
B
Boiler
Model
MAX
Flow Rate
20° F
temperature
rise
MIN
Flow Rate
50° F
temperature
rise
Flow Rate
Delta T1
protection
67° F
temperature
rise
AB-80
7.9 2.9 2.3
AB-120
12.0 4.3 3.4
AB-155
15.2 6.1 4.5
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