Weil-McLain Aqua Balance WMB-155 Manual page 49

W
TM
AquaBalance
20 Gas piping
Gas pipe sizing
1. See page 16 for gas line sizing information.
Check gas pressure at inlet to boiler
1. See Figure 60 for location of the gas inlet pressure test port.
Check the operational (working) gas inlet
pressure
1. Set up the boiler to operate at maximum rate as described in
section " Test mode" Figure 99, page 74.
2. With the boiler operating at maximum rate check that the op-
erational (working) gas pressure at the inlet gas pressure test
port (see above) complies with the requirements of Table 2 .
3. Ensure that this inlet pressure can be obtained with all other
gas appliances in the property working.
Measure the gas rate
Measure the gas rate and check against following Table 2:
Table 2
Gas rate for Combi and Heating Only boilers
Gas Rate (Natural Gas)
After 10 minutes from cold
Combi Maximum rate
Boiler
model
3
ft /h
WMB-80
78.4
WMB-120
117.6
WMB-155
151.9
Part number 550-100-305/0118
M -
ALL OUNT GAS FIRED WATER BOILER
(continued)
Minimum rate
3
ft /h
7.8
11.8
15.2
—
Boiler Manual
For natural gas or liquefied petroleum (propane) gas, the pres-
sure required at gas valve inlet pressure port (verify minimum
gas pressure when all gas appliances are in operation):
a. Maximum: 13" w.c. with no flow (lockup) or with boiler
on.
b. Minimum: 3.5" w.c. gas pressure, with gas flowing (verify
during boiler startup, while boiler is at high fire)
c. Nominal gas pressure: 11.0" w.c.
4. Install 100% lockup gas pressure regulator in supply
line if inlet pressure can exceed 13" w.c. at any time.
Adjust lockup regulator for 13" w.c. maximum.
Figure 60
Inlet test port on gas valve
Inlet test port
49