Williamson Series 2 Manual page 39

12 Troubleshooting
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.
• Are main manual shutoff valve and boiler gas valve open?
No
• TURN OFF POWER to boiler at service switch or breaker.
• Open main manual shutoff valve and boiler gas valve (per
Operating instructions in this manual). Wait at least 45 seconds.
• Turn on power at service switch or breaker. Allow boiler to cycle.
Does FLAME light flash now?
No
• Verify inlet gas pressure at gas
• Boiler should be in
normal operating
sequence.
• Observe operation
until thermostat is
satisfied and blower
Is gas present at gas valve inlet and
has completed its
post-purge cycle.
▲ ▲
•
TURN OFF POWER
to boiler at service switch or
breaker.
• Remove burner shield (see
Figure 25, item 4, page 42
for location).
• Verify pilot gas line is not
kinked, obstructed or
damaged and is correctly
attached to pilot and gas
valve.
• Verify pilot ignition electrode,
electrode ceramic and spark
lead wire from control are in
good condition. Spark gap
should be approximately 1/8".
• Correct any above problems,
replacing pilot if burner or
wiring is damaged.
• Reinstall burner shield to
operate boiler for retest after
any changes or corrections.
• If none of the above corrects
problem, then replace the
control module and retest.
Part Number 550-142-785/0812
GWI Series 2 Gas-Fired Water Boilers – Boiler Manual
continued
CHART 6 — FLAME light flashing and POWER light on steady
ALSO — Troubleshooting failure to establish main flame
Yes
Yes
valve:
Natural gas — 5.0" w.c. min/14.0"
w.c. max
Propane — 11.0" w.c. min/14.0"
w.c. max
within above range?
Yes No
• Contact gas supplier to correct
pressure or gas supply.
▲ ▲
•
TURN OFF POWER
to boiler at service switch or
breaker.
• Remove burner shield (see
Figure 25, item 4, page 42 for
location).
• Verify pilot burner is securely
attached to pilot bracket, bracket
is securely attached to cross tie,
and there is no corrosion on the
parts which would affect the
ground path for flame sense.
• Verify that pilot flame rod, flame
rod ceramic and lead wire from
control module to flame rod are in
good condition.
• Correct any above problems,
replacing pilot if burner or wiring
is damaged.
• Is pilot flame visible through inspection port?
No
• Check the voltage across
terminals PV and C of the
gas valve.
Is 24 VAC present there?
Yes No
• If the wiring from the
control module to gas
valve is intact, replace the
control module.
• Retest.
• Verify inlet gas pressure at gas valve:
Natural gas — 5.0" w.c. min/14.0" w.c. max
Propane — 11.0" w.c. min/14.0" w.c. max
Is gas present at gas valve inlet and within above range?
No
▲ ▲
•
TURN OFF POWER to boiler at service switch or breaker.
• Check flame signal — Detach sense lead from ignition control
(Figure 23, item 8, page 33).
• Connect negative lead of MICROAMMETER to control sense
terminal (Figure 23, item 8, page 33). Connect positive lead of
MICROAMMETER to sense wire.
• DISCONNECT red wire connected to terminal MV of the gas
valve.
• Turn on power to boiler and allow to cycle. As soon as pilot is
burning, the MICROAMMETER should read at least 1.0
microamp.
Is flame signal at least 1.0 microamp?
No
• If none of the previous steps
(including replacing pilot)
corrects problem, then replace
the control module, reinstall
burner shield and retest.
Yes
• Make sure ground wire
terminal is securely fastened
to control module mounting
screw.
• Check the voltage across
terminals MV and C of the
gas valve.
Is 24 VAC present there?
No Yes
Yes
Yes
• If the wiring from the
control module to gas
valve is intact, replace the
control module and retest.
39