Dunkirk Q95M-200 Modulating Condensing Boiler - Manual (Page 18)

18
29
Blower turning when it should be
off.
1
Check boiler wiring against wiring diagram.
Replace line voltage and low voltage wiring harnesses if necessary.
Replace control module if wire replacement doesn’t resolve.
30
High limit operation:
Temperature rise across boiler too
high.
1
Flow rate too low.
Check system for:
Verify boiler and system are full of water.
Inspect and verify system piping and components.
Verify piping agrees with boiler manual recommendations.
Make sure system pressure drop is not too high.
2
Verify operation of boiler circulator.
Check voltage at circulator junction box to ensure 120 vac when boiler operates. If
no voltage, check wiring and wiring connections.
High voltage terminal strip terminals 5 and 6 should show 120 vac for space
heating; terminals 3 and 4 should show 120 vac for DHW.
Replace circulator if powered but not operating.
Replace line voltage wire harness if necessary.
Replace control module if wire replacement doesn’t resolve.
61 Pressure switch contacts closed. 1
Check pressure switches for proper operation.
Replace pressure switch if moisture has entered switch.
65
Blower not operating when turned
on.
1
Turn off power to boiler. Remove line voltage connector at blower. Restart boiler
and check voltage across blower plug terminals. If 120 vac is NOT present, inspect
wiring and tightness of connections.
Replace line voltage wire harness if necessary.
Replace control module if wire harness replacement doesn’t resolve.
2
If 120 vac is present on blower wire harness, replace harness and retry. If problem
persists, replace blower motor.
9 - TROUBLESHOOTING