Part number 550-143-010/1021
89
GV90+
series
2
gas-fired water boiler – boiler manual
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 fol
-
low 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?
No
Yes
•
If you have sufficient heat — boiler should follow normal
operating sequence (
•
If you have less than sufficient heat —
Is vent or combustion air piping free of blockage?
No
Yes
•
Wait for boiler water to cool to temperature 20 to 30 °F
lower than temperature set on the limit.
Are limit switch contacts closed?
No
Yes
Are all red lights off?
No
Yes
•
Wait 30 seconds.
Are all red lights
off?
No
Yes
•
Wait for cast iron
block to cool to room
temperature.
Are block switch
contacts closed?
No
Yes
•
Check across thermal switch
leads with continuity checker.
Is circuit closed?
No
Yes
•
Check across limit
switch contacts with
continuity checker.
Are contacts closed?
Yes
No
•
Replace IBC.
•
Retest.
•
Replace IBC.
•
Retest.
•
Correct conditions and
recheck operation. See
sequence of operation,
.
•
Repair/replace circula
-
tor. Retest.
•
Repair/replace wiring.
Retest.
•
Contact your Weil-
McLain sales represen
-
tative.
•
Replace
switch.
•
Retest.
•
Replace
thermal switch.
•
Retest.
•
Replace
IBC.
•
Retest.
•
Replace limit switch.
•
Retest.
•
Excessive block temperature has been reduced to safe
operating level. Check for low water level or mineral de
-
posits in sections. Correct before proceeding.
•
Restart boiler and check sequence of operation
•
Boiler water temperature exceeded setting on limit switch
with thermostat calling for heat. Boiler is OK. (See se
-
quence of operation,
•
Also check operation of setting limit (should be above
140°F.).
•
Check block switch on top of
boiler with continuity checker.
Are contacts closed?
No
Yes
•
Boiler is in standby.
•
Set thermostat to call for heat
and recheck operation.
•
Verify sequence of operation,
.
•
Remove system circulator harness plug from
CIR-
CULATORS
plug receptacle (long harness) (see
, Item 4). Check with voltmeter
across left-side
120 VAC N
and
120 VAC H
pins of
receptacle.
Does voltmeter show
120 VAC
across pins?
No
Yes
Troubleshooting
(continued)