Troubleshooting - Williamson-Thermoflo GWS-090E 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 26-32.
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 0-10.
c. Continuity checker.
d. U-tube manometer and 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:
a. With boiler off — 13" w.c. maximum natural or propane gas pres-
sure 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.
c. Verify gas manifold pressure as shown on page 24.
Check pressure switch setting
Make sure boiler water temperature is 100 °F or
cooler before starting procedure to obtain appropri-
ate readings.
1. See Figure 14 and Table 8.
Table 8 Pressure switch setpoint (for elevations
above 2,000 ft, contact your local supplier for
details.)
Boiler model number
GWS-090E
2. Remove both air pressure switch hoses from air pressure
switch.
3. Install tees and tubing as shown in Figure 14 to inclined ma-
nometer.
Part Number 550-110-737/1108
GWS-090E Gas-Fired Water Boiler – Boiler Manual
Figure 14
4. Turn off gas valve and set thermostat to call for heat. Inducer
5. Check for 24 VAC between both air pressure switch termi-
6. If manometer reading is above the setpoint of the switch (see
Troubleshooting air pressure reading
1. If manometer reading is lower than the setpoint of the switch
Return to normal operation
When pressure reading is correct and air pressure switch is
operating properly — remove tees and reinstall hoses to air
Inches W.C.
pressure switch.
1.71
Checking pressure switch
will run but burners will not ignite.
nals.
Table 8), but there is not 24 VAC between both air pressure
switch terminals — replace air pressure switch.
(see Table 8) — 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
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 14.
25