85
13
Troubleshooting
(continued)
FAULT
CAUSE
CORRECTIVE ACTION
Combi Boiler
is Running
but Does
Not Supply
Heated Water
to Space
Heating
System
A DHW demand is present.
• Wait until DHW demand has ended, then combi
unit should provide heated water to the space heating
system. The Noble Combi Boiler does not provide
heated water during a DHW demand.
Diverter valve is not in DHW position (heated
boiler water is being provided to the combi
plate heat exchanger rather than to the
space heating system).
• Check wiring harness connections between the Low
Voltage Connection Board (CN4) and the combi
diverter valve motor.
• Check that diverter valve motor is operating.
• Verify that the voltage between wire CN4-1 (Brown)
and ground is 24 Vac during a space heating
demand.
• Replace combi diverter valve motor, Low Voltage
Connection Board, or wire harness.
Space
Heating
System Heat
Emitters Get
Hot During
a DHW
Draw and
the Combi
Boiler does
not Provide
Hot Enough
Domestic
Hot Water
Diverter valve not operating correctly.
• Verify diverter valve motor operation. If combi diverter
valve motor is operating correctly, replace the flow
group on the combi water set.
• Verify wiring harness connections between the Low
Voltage Connection Board, and the diverter valve motor,
and between the main control board and the Low
Voltage Connection Board.
• Verify that voltage between CN4-2 (Black) and ground
is 24 Vac and that voltage between CN4-1 (Brown) and
ground is 0 Vac. If voltages are incorrect, replace the
Low Voltage Connection Board, wire harness, or main
control board.
• If voltages are correct and diverter valve motor is not
operating correctly, replace the combi diverter valve
motor.
Installation & Service Manual
Table 13-4 (continued from previous page) Troubleshooting Chart - Fault Messages Displayed on Boiler Interface
F I R E T U B E C O M B I
™
