Operating instructions

38
Part Number 550-142-784/0812
GWA Series 2 Gas-Fired Water Boilers – Boiler Manual
12 Troubleshooting – spark-ignited pilot boilers
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.
• Boiler is in standby.
• Set thermostat to call for
heat and recheck
operation.
• Verify Sequence of
operation, Figure 14,
page 20.
Replace control module.
Retest.
• Has it been at least 5 minutes since setting thermostat to
call for heat? If not, wait 5 minutes. Is system heating?
• Is thermostat set to call for heat? Remove thermostat
wires at boiler and check continuity across the two wires.
If circuit isn't closed, check external thermostat (zone
valve, relay, etc.) wiring. Correct problems and retry.
• Reconnect external thermostat wiring at boiler.
Is thermostat circuit closed (continuity across wires)?
• If you have sufficient heat — boiler should be in normal
operating sequence. (See normal sequence of operation,
Figure 14, page 20.)
• If you have less than sufficient heat —
Is vent or combustion air piping free of blockage?
No Yes
• Correct conditions and
recheck operation.
• See Figure 14, page 20
for normal sequence of
operation.
Contact your Williamson-
Thermoflo sales
representative.
• Replace control
module.
• Retest.
• Repair/replace
circulator. Retest.
• Repair/replace
wiring. Retest.
• Remove CIRCULATOR harness plug from
CIRCULATOR plug receptacle (Figure 17,
Item 7, page 32). Check with voltmeter across
pins of control module receptacle.
Does voltmeter show 120 VAC across pins?
No Yes
Is boiler System circulator operating?
• Wait 5 minutes.
Is FLAME light on?
NoYes
Is LIMIT light on?
No Yes
Are all red lights off?
No Yes
Wait 30 seconds.
Are all red lights off?
No Yes
• Replace control module.
• Retest.
• Check temperature
sensor for correct
resistance.
Are resistance values
correct?
No Yes
No Yes
No Yes
Check spill switch and
rollout switch continuity —
are switches closed?
No Yes
• Check any other
limit controls wired
into the limit
circuit. If all are
OK, then replace
control module.
• Retest.
CHART 6 — Spark-ignited pilot — Insufficient heat or no heat (POWER light on steady)
• Reset spill switch, or replace rollout switch.
• Replace temperature
sensor.
• Retest.
If rollout thermal fuse element or spill switch has
opened, determine cause and correct condition.
Failure to do so will cause severe personal injury,
death or substantial property damage.