Williamson-Thermoflo GWC-070 Manual page 82

GWC -
gas fired water boiler
Troubleshooting
CHART 4
Electrical shock hazard — Wherever you see TURN OFF POWER, follow the instructions. Failure to follow
instructions could result in severe personal injury, death or substantial property damage.
• Reset boiler control by turning off power at service switch or
turning down thermostat for at least 45 seconds.
• Remove BLOWER plug (Figure 89, page 76, Item 3) from
plug receptacle of IBC.
• Place voltmeter leads across the 120 VAC N and 120 VAC H
pins of the BLOWER receptacle.
Does the voltmeter indicate 120 VAC?
No
• TURN OFF POWER at service switch.
Does blower wheel turn freely by hand?
No
• Properly position blower
wheel on blower motor shaft
and tighten set screw. (Or
replace blower housing
assembly.)
• Retest.
• Remove one of the red wires connected to the pressure
switch.
• Check continuity across the switch terminals.
Does the ohmmeter indicate the switch is closed?
No
• Replace IBC.
• Retest.
82
— Boiler Manual
(continued)
PRESS SWITCH & POWER lights flashing
Does blower motor operate?
No
Yes
Yes
• Replace blower motor.
(Also check blower
housing assembly.
Replace if necessary.)
• Retest.
Yes
• Check air pressure switch per page 73.
• Replace if necessary.
• Retest.
• Thermostat should call for heat and appropriate zone valves
open.
Is blower wheel turning at speed of blower motor?
No
• TURN OFF POWER at
service switch.
• Properly position blower
wheel on blower motor
shaft and tighten set screw.
(Or replace blower housing
assembly.)
• Retest.
• Boiler should be in normal operating se-
quence (Figure 71, page 63).
• Observe operation until thermostat is satis-
fied and blower has completed its post-
purge cycle.
• Check condensate trap.
Is blower wheel turning at speed of blower motor?
Is there condensate present?
No
No
Are vent or combustion air
passages blocked?
No Yes
• Clear passages and recycle boiler.
• Recheck boiler operation.
Yes
Yes
• Wait 5 minutes.
Is purge light flashing?
No Yes
Yes
Yes
• Drain condensate.
• Retest.
Part number 550-142-056/0411