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W
TM
AquaBalance
17 Primary/Secondary System Piping
Closed-type expansion tank:
DO NOT use a closed-type tank if connecting to a
water heater that is equipped with an automatic air
vent.
Figure 49, shows suggested piping when using a closed-type expan-
sion tank, in which the air is directly in contact with tank water.
Connect piping (½" or ¾") from the air separator outlet to the
tank fitting. Slope any horizontal piping a minimum of 1 inch per
5 feet of horizontal pipe.
Always use a tank fitting such as the B&G Tank-trol or Taco Taco-
trol (shown). The fitting reduces gravity flow of water in the pip-
ing to the tank, avoids air bubbling through the tank water, and
provides the proper fill height in the tank.
C
orrect all leaks in the system or tank piping. Leaks
allow air to escape from the system and will cause
water-logging of the tank. This will result in water
loss through the boiler relief valve due to over-
pressurization. NEVER use an automatic air vent
in a system equipped with a closed-type expansion
tank. The air removed from the system will cause
water-logging of the expansion tank.
Closed-type expansion tank—Follow tank manufac-
turer's instructions for filling the tank. Typical tank
sizing provides for approximately 12 PSIG when the
tank is filled to the normal level and system water is
cold. Note that boiler relief valve is set for 30 PSIG.
Operation pressure of system, after temperature
expansion above cold fill pressure, should not exceed
24 PSIG to avoid weeping of relieve valve.
Graph 1
Pressure drop through
36
1 = Boiler Pressure Drop with 3/4'' near boiler piping (80KBTU and120 KBTU)
34
2 = Boiler Pressure Drop with 1'' near boiler piping (80KBTU and120 KBTU)
32
3 = Boiler Pressure Drop with 1 '' near boiler piping (155 KBTU)
4 = Boiler Pressure Drop with 1 1/4'' near boiler piping (155 KBTU)
30
28
26
24
Taco 0014
22
20
18
B&G NRF 25 (High)
16
14
12
Taco 007
10
8
6
4
2
0
0
1
Part number 550-100-305/0118
M
-
ALL
OUNT GAS
FIRED WATER BOILER
AquaBalance
Taco 0015 (High)
Grundfos UPS 15-58
(High)
2
3
4
—
Boiler Manual
(continued)
Figure 49 Piping to closed-type expansion tank
80/120/155 heat exchanger
TM
Taco 0011
5
6
7
Flow - gpm
1
3
4
2
8
9
10
11
12
39
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