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Part number 550-110-260/0200
51
Boiler Manual
continued
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.
• Replace rollout switch.
• Boiler is in standby.
• Set thermostat to call for
heat and recheck
operation.
• Verify Sequence of
operation, Figure 18,
page 31.
Replace control
module. Retest.
• Boiler water temperature exceeded
setting on limit switch with thermostat
calling for heat. Boiler is OK. (See normal
sequence of operation, Figure 18, p. 31.)
• Also check setting on limit switch (should
be above 140˚F.).
• 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 18.)
• 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 18, page 31
for normal sequence of
operation.
Contact your Weil-McLain
sales representative.
• Replace control
module.
• Retest.
• Repair/replace
circulator. Retest.
• Repair/replace
wiring. Retest.
• Remove CIRCULATOR harness plug from
CIRCULATOR plug receptacle (
Figure 25, Item
7, page 44
). 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
• Wait for boiler water to cool to temperature 20 to 30 ˚F
lower than temperature set on limit switch.
Are limit switch contacts closed?
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 limit switch
contacts with continuity
checker.
Are limit switch contacts
closed?
No Yes
No Yes
No Yes
• Replace
limit switch.
• Retest.
No Yes
Check rollout switch
continuity — is switch
closed?
No Yes
• Check any other
limit controls wired
into the limit
circuit. If all are
OK, then replace
control module.
• Retest.
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.