43
Part Number 550-142-320/0720
GWA
Series 3
Gas-Fired Water Boilers –
Boiler Manual
13 Troubleshooting – spark-ignited pilot boilers
CHART 5 –– Spark-ignited pilot –– FLAME
light flashing and
POWER
light on steady
ALSO
––
Troubleshooting failure to establish main flame
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.
• Is pilot flame visible through inspection port
?
No
Yes
Are main manual shutoff valve and gas valve open?
No
Yes
•
▲ 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
Yes
•
▲ TURN OFF POWER ▲
to
boiler at service switch or
breaker.
• Remove base access panel
(see Figure 29
, item 4
,
page 46) for location.
• Contact gas supplier to correct
pressure or gas supply.
• Check the voltage across
main gas valve terminals
of the gas valve.
Is
24 VAC
present there?
Yes
No
• Make sure ground wire
terminal is securely
fastened to control module
mounting screw.
• 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
Yes
•
▲ TURN OFF POWER ▲
to boiler at service switch or breaker.
• Check flame signal – Detach sense lead from ignition control
(
Figure
26, Item 8, page 38).
• Connect
negative
lead of MICROAMMETER to control
sense terminal
(
Figure
26, Item 8, page 38). Connect
positive lead of MICROAMMETER to sense wire.
• DISCONNECT
red
wire connected to main gas valve termi-
nal 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
Yes
• Check the voltage across
main gas valve terminals
of the gas valve.
Is
24 VAC
present there?
No
Yes
• 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?
Yes
No
• Boiler should be in
normal operating
sequence.
• Observe operation
until thermostat is
satisfied and vent
damper has closed.
• Verify pilot gas line is not
kinked, obstructed or
damaged and is correctly at-
tached 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 base access panel to
operate boiler for retest after
any changes or corrections.
• If none of the above corrects
problems, then replace the
control module, reinstall base
access panel, and retest.
•
▲ TURN OFF POWER ▲
to boiler at service switch or
breaker.
• Remove base access panel
(see Figure 29
, item 4
,
page 46) for location.
• Verify pilot burner is securely
attached to pilot bracket,
bracket is securely attached to
cross-tie, and there is no cor-
rosion on 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 wir-
ing is damaged.
• If none of the previous steps
(including replacing pilot)
corrects problem, then replace
the control module, reinstall
base access panel and retest.
• If the wiring from the
control module to gas
valve is intact, replace the
control module and retest.
