31
Part Number 550-142-785/0812
GWI
Series 2
Gas-Fired Water Boilers –
Boiler Manual
12 Troubleshooting
Label all wires prior to disconnection when servic
-
ing controls. Wiring errors can cause improper and
dangerous operation.
Never jumper (bypass) rollout thermal fuse element
or any other device except for momentary testing as
outlined in “Troubleshooting” charts,
pages 34 - 40.
Severe personal injury, death or substantial property
damage can result.
Burner access panel must be in position during
boiler operation to prevent momentary flame rollout
on ignition of main flame. Severe personal injury or
substantial property damage will result.
Before troubleshooting:
1. Have the following items:
a. Voltmeter that can check 120 VAC and 24 VAC.
b. Microammeter with a minimum scale range of 0-25.
c. Continuity checker.
d. U-tube manometer
e. Inclined manometer with 0 – 2” w.c. range.
2. Check for 120 VAC (minimum 102 VAC to maximum 132 VAC)
to boiler.
3. Make sure thermostat is calling for heat and contacts (includ
-
ing appropriate zone controls) are closed. Check for 24 VAC
between thermostat wire nuts and ground.
Check the following:
1. Wire connectors to control module are securely plugged in at
module and originating control.
2. Gas pressures (connect U-tube manometer at gas valve tap
-
pings):
a. With boiler off — 13” w.c. maximum natural or propane
gas pressure upstream of gas valve.
b. With boiler on:
• 5” w.c. minimum natural gas pressure or 11” w.c. propane
gas pressure upstream of gas valve.
• 3.5” w.c. minimum natural gas pressure or 10” w.c. propane
gas pressure downstream tapping on gas valve — Can
be adjusted by regulator on gas valve.
How to check pressure switch setting (
if specified
in Troubleshooting charts
)
Make sure boiler water temperature is 100 °F or
cooler before starting procedure to obtain appropri
-
ate readings.
1. See
Figure 21 and Table 9.
2. Remove both air pressure switch hoses from air pressure
switch.
3. Install tees and tubing as shown in
Figure 21 to inclined
manometer.
4. Turn off gas valve and set thermostat to call for heat. Inducer
will run but burners will not ignite.
5. Check for 24 VAC between both air pressure switch terminals.
6. If manometer reading is above the setpoint of the switch (see
Table 9
), but there is not 24 VAC between air pressure switch
terminals “C” and “NO” — replace air pressure switch.
Troubleshooting air pressure reading
1. If manometer reading is lower than the setpoint of the switch
(see
Table 9
) — check for possible causes:
• blockage in hoses
• obstruction in inducer housing outlet
• loose inducer wheel on motor shaft
• inducer motor not in proper rpm
• inducer back plate not sealed properly
• blockage in block assembly
• blockage in flue pipe or termination
• incorrect pressure switch
Return to normal operation
When pressure reading is correct and air pressure switch is
operating properly — remove tees and reinstall hoses to air
pressure switch.
The boiler will not operate correctly unless pressure
switch hoses are correctly located. The red hose
connects from the right side (negative) hose barb
to the flue collector. The white hose connects from
the left side (positive) hose barb of the switch to the
connector box (between flue collector and inducer)
as shown in Figure 21.
Table 9
Pressure switch setpoint (for elevations
above 2,000 ft, contact your local supplier for
details.)
Boiler model number
Inches W.C.
GWI-047 and GWI-063
1.19
GWI-095
1.08
GWI-127
0.86
GWI-158
0.61
GWI-190
0.76
Figure 21 Checking pressure switch
