55
Part Number
550-110-290/0219
CGt
GAS-FIRED WATER BOILER — Series 2 —
Boiler Manual
Troubleshooting — control module lights
(cont.)
12c
CHART 7 –– Insufficient heat or no heat to system (POWER light on steady)
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.
• 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)?
No
Yes
Is boiler System circulator operating?
No
Yes
• Wait 5 minutes.
Is
FLAME
light on?
Yes
No
Is
LIMIT
light on?
No
Yes
Are all red lights off?
No
Yes
• Wait 30 seconds.
Are all red lights off?
No
Yes
• Replace rollout switch.
If rollout thermal fuse element has
opened, determine cause and correct
condition. Failure to do so will cause
severe personal injury, death or
substantial property damage.
• Check ambient temperature
switch. If switch is open,
boiler room temperature is
too high. Check air open-
ings. Add additional open-
ings if needed to keep room
temperature within limits.
• Check limit switch contacts
with continuity checker.
Are limit switch contacts
closed?
No
Yes
• Replace control module.
• Retest.
• Replace control
module.
• Retest.
• Repair/replace
circulator. Retest.
• Repair/replace wiring.
• Retest.
• Check any other limit
controls wired into
the limit circuit. If all
are OK, then replace
control module.
• Retest.
• Correct conditions and
recheck operation.
• See Figure 27, page 34
for normal
Sequence of
operation.
• Boiler is in standby.
• Set thermostat to call for
heat and recheck operation.
• Verify
Sequence of
operation, Figure 27,
page 34
.
• Remove
CIRCULATOR
harness plug from
CIRCULATOR
plug receptacle (Figure 33
, Item 7,
page 48
). Check with voltmeter across pins of
control module receptacle.
Does voltmeter show
120VAC
across pins?
No
Yes
• Replace control module.
• Retest.
• If you have sufficient heat –– boiler should be in normal
operating sequence. (See normal
Sequence of operation
,
Figure 27, page 34.
• I
f you have less than sufficient heat, first check 3-way valve to
be sure it is not diverting flow to tankless coil. If 3-way valve
is supplying tankless coil, check tankless limit to be sure it set
correctly. If 3-way valve and tankless heater low limit are set
and operating correctly ––
Is vent piping free of blockage?
No
Yes
• Boiler water temperature exceeded setting on
limit switch with thermostat calling for heat.
Boiler is OK. (See normal
Sequence of opera-
tion,
see
Figure 27, page 34.
• Also check setting on limit switch (should be
above 140 °F ).
• Check heat loss calcula-
tion verus boiler size.
• Clock gas input.
Check rollout switch continuity
– Is switch closed?
No
Yes
Check if 3-way valve is
allowing water to return to
boiler from system. If not
replace 3-way actuator.
• Replace limit
switch.
• Retest.
• Wait for boiler to cool to temperature 20 to 30 °F lower than
temperature set on limit switch.
Are limit switch contacts closed?
No
Yes
