Weil-McLain GV90+, Manual

Page: 84 / 108

Part number 550-143-010/1021
84
GV90+
series
2
gas-fired water boiler – boiler manual
CHART 2
TSTAT/CIRC & POWER lights flashing
Electrical shock hazard
— Wherever you see TURN OFF POWER, follow the instructions. Failure to fol -
low instructions could result in severe personal injury, death or substantial property damage.
Is return water temperature sensor clamped
securely to the return pipe in the boiler?
Yes No
• Remove CIRCULATORS plug ( Figure 93, page 80 , Item 4)
from plug receptacle of IBC.
• Place voltmeter leads across the right-side 120VAC N and
120VAC H pins of the CIRCULATORS receptacle.
Does the voltmeter indicate 120 VAC?
No Yes
Is boiler internal Bypass circulator operating?
No Yes
• Test wire continuity of
circulator wire harness.
Is harness ok?
No Yes
• Check the boiler internal return pipe where it enters the
boiler sections. The TSTAT/CIRC and POWER lights
will flash after 30 minutes as long as the return water
temperature is less than 130 °F.
• Wait up to 20 minutes to give the boiler and system a
chance to respond.
Does problem persist?
No Yes
• Attach sensor to pipe with clamp provided.
• Follow return temperature sensor checking procedure
on page 78 . Replace sensor if necessary.
• Retest.
• Check for stray voltage on the incoming thermostat wires.
Disconnect the two external wires connected to the boiler
thermostat wires.
• Connect a voltmeter across the two incoming wires. Close each
thermostat, zone valve and relay in the external circuit one at a
time and check the voltmeter reading across the wires. There
should NEVER be a voltage reading. If a voltage does occur
under any condition, check and correct the external wiring.
(This is a common problem when using 3-wire zone valves.)
• Once the external thermostat circuit wiring is checked and cor -
rected if necessary, reconnect the external thermostat circuit
wires to the boiler thermostat wires and allow the boiler to cycle.
Did you find and correct a voltage across the two external thermostat circuit wires?
Yes No
• Boiler should now operate per the normal sequence of op -
eration ( Figure 75, page 66 ) if wiring was corrected.
• Replace the IBC.
• Retest.
• Boiler may now be operating normal -
ly. Verify against normal sequence of
operation ( Figure 75, page 66 ).
• If boiler appears not to be heating, troubleshoot boiler
per CHART 7 , page 89. If problem cannot be resolved,
replace water temperature sensor and retest. Then
replace IBC if sensor does not correct the problem.
• If boiler is heating, but the temperature at the return
pipe does not increase above 130 °F, there may be an
incorrectly-piped external circulator forcing water through
the boiler. Check external piping and correct.
• Replace circulator harness.
• Retest.
• Reconnect circulator harness to IBC.
• 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.
• With harness connected and power to circulators, check for
120 VAC at circulator harness terminals. If no voltage is pres -
ent with circulators under load. Replace IBC and retest.
• If problem persists, replace the Bypass circulator.
• Retest.
Troubleshooting
(continued)