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79Part number 550-141-850/0699
• Installation • Start-Up • Parts • Maintenance
• Remove CIRCULATORS plug (
Figure 34, Item 4
) from
plug receptacle of control module.
• Place voltmeter leads across the
120 VAC N
and
120 VAC H
pins of the CIRCULATORS receptacle on the
side corresponding to the circulator not operating.
Does the voltmeter indicate 120 VAC?
CHART 6
—
TSTAT CIRC
light flashing and
POWER
light on steady
• This is not a lockout mode. The control module is signaling that the return water temperature sensor is detecting a temperature
less than 40 ˚F.
• While the temperature at the boiler return water temperaure sensor is less than 40 ˚F, both of the internal boiler circulators will
run continuously, even if there is no call for heat (though the boiler will not fire until the thermostat calls for heat). This operation
is intended to reduce chances of freezing during system down times by keeping water flowing.
Electrical shock hazard — Wherever you see
▲
TURN OFF POWER
▲
, follow the instructions. Failure to follow
instructions could result in severe personl injury, death or substantial property damage.
No Yes
• Attach sensor to pipe
with clamp provided.
• If problem persists,
replace return water
temperature sensor.
• Retest.
No Yes
Is return water temperature sensor clamped
securely to the return pipe in the boiler?
• Replace GCM (control
module).
• Retest.
• Test wire continuity of
circulator wire harness.
Is harness ok?
No Yes
• Replace circulator
harness.
• Retest.
• Reconnect circulator harness to GCM.
• Attempt to get the circulator started by giving it a sharp
rap on the end of the circulator motor (to release a
possibly locked impeller).
• If the circulator begins to operate, allow it to operate for a
few minutes to see if the problem clears.
• If problem persists, replace the bypass circulator.
• Retest.
No Yes
Is there a call for heat?
(Verify by removing thermostat wirings at boiler and
checking continuity across external wires)
• This is normal
operation for water less
than 40 ˚F at boiler
internal return pipe.
• Condition should
change after a call for
heat, when the boiler
will heat up the water.
• Wait 10 minutes to
allow heat from the
boiler to raise the water
temperature.
Does LIMIT light quit
flashing (and pipes begin
to heat up)?
No Yes
• Boiler is not heating.
• Troubleshoot boiler
using
CHART 8
.
• Boiler should now operate normally.
• Verify correct sequence of operation using Figure 22.
No Yes
Are both boiler internal circulators operating?