Igniter; Gas Valve; Blower Housing; Thermal Fuse - Williamson-Thermoflo GWC-070 Manual

GWC -
gas fired water boiler
Troubleshooting

Igniter

Wait several minutes until igniter cools down before at-
tempting replacement. Failure to do so will cause severe
personal injury.
1. Disconnect igniter (Figure 82) from igniter wiring harness and
remove igniter before removing from blower assembly.
2. Replace igniter gasket if original gasket is frayed or damaged OR
if room-temperature resistance across igniter is not between 40
and 95 ohms.
3. Igniter is fragile — handle with care. Do not touch igniter surface
with bare hands. Body oils can cause failure of the carbide.

Gas Valve

The gas valve (Figure 83) operates with a negative pres-
sure at the outlet — approximately –0.2" w.c. — DO
NOT set gas pressure higher than this.
Follow instructions in this manual carefully if testing
gas valve outlet pressure. Failure to comply can result in
severe personal injury or death.
The gas valve outlet is bolted to the gas line adapter and
sealed with an o-ring. When replacing valve, replace only
with valve listed in this manual for use with the GWC
boiler. Failure to comply could result in severe personal
injury, death or substantial property damage.

Blower Housing

Do not disassemble blower housing (Figure 84)
fire or explosion causing severe personal injury, death or
substantial property damage can result. If you suspect a
problem, replace blower housing. Follow instructions on
page 70 for blower housing removal and replacement.

Thermal fuse

1. The thermal fuse (Figure 85) protects vent pipe from excess flue
temperatures.
2. If the thermal fuse opens, it must be replaced. See page 92 for
replacement information.
If the thermal fuse opens, investigate the cause before
replacing switch and starting the boiler. DO NOT attempt
to jumper the switch. Failure to comply could result in
severe personal injury, death or substantial property
damage.

Return temperature sensor

1. See Figure 86.
2. Resistance check method:
a. With the boiler operating, use a contact thermometer to
measure the temperature of the return pipe next to the return
temperature sensor. Make a note of the temperature.
b. Turn the boiler ON/OFF switch off.
74
— Boiler Manual
(continued)
. A
Igniter
Figure 82
Gas valve
Figure 83
Blower housing
Figure 84
Thermal fuse
Figure 85
Return temperature sensor
Figure 86
Part number 550-142-056/0411