84
13
Troubleshooting
FAULT
CAUSE
CORRECTIVE ACTION
No Hot Water
at Faucets
Flow switch is not triggering a DHW demand
(red light on flow switch sensor does not turn
on during a DHW draw).
• Verify DHW flow is at least 0.4 gpm.
• Check wiring harness connections between the low
voltage connection board connector CN4 and the
flow switch sensor.
• Verify that voltage between wires CN4-8 (Blue) and
CN4-3 (Red) is 9 - 10 Vdc. If no voltage, replace Low
Voltage Connection Board.
• Replace flow switch sensor.
Flow switch input not received by main
control board (red light on flow switch
sensor turns on during a DHW draw, but
combi boiler does not start a DHW Call for
Heat).
• Check wiring harness connections between the Low
Voltage Connection Board and the main control
board.
• Replace Low Voltage Connection Board.
• Replace Main Control Board.
Diverter valve is not in DHW position
(heated boiler water is being provided to
the space heating system rather than to
the combi plate heat exchanger.
• 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 CN4-2 (Black) and
ground is 24 Vac during a DHW demand.
• Replace combi diverter valve motor, Low Voltage
Connection Board, or wire harness.
DHW Water
is not Hot
Enough
DHW set point is too low.
• Set DHW Setpt to the appropriate temperature based
on the anti-scald mixing valve set point.
Anti-scald mixing valve set point is too low.
• Verify the anti-scald mixing valve is set to the desired
temperature.
DHW flow rate is too high (combi boiler
is firing at 100% in DHW Mode, but DHW
temperature on screen is lower than the
DHW Setpt on the screen).
• During maximum flow conditions at all fixtures, adjust
the field supplied flow control valve at the outlet of the
mixing valve (or combi DHW outlet) to reduce the hot
water flow until the DHW temperature reaches the
DHW set point.
Combi DHW sensor fault (display unit will
show "Combi Sensor Fault").
• See Combi Sensor Fault.
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
™
