Table of Contents
Advertisement
Cause:
It is not proven that the non-return valve of the unit is closed.
Corrective action:
Check and repair or replace NRV.
Display message
F6
Reason
Cause:
Bad wiring/connection in the flue gas sensor circuit.
Corrective action:
Check for loose wiring/connections in the flue gas sensor circuit.
Cause:
Bad temperature sensor causing a fault signal.
Corrective action:
Replace flue gas sensor.
Display message
F7
Reason
Cause:
Heat exchanger polluted and not able to transfer enough heat to system water.
Corrective action:
Check and clean heat exchanger.
Cause:
Bad flue gas sensor or sensor connection (partly shorted).
Corrective action:
The sensor is of the type NTC. This means as the temperature rises the measured resistance is lowered. A
partly shorted sensor will drop the resistance and therefore 'measure' a raise in temperature when actually
there is none.
Check for moist in the sensor connections or replace sensor.
Cause:
There is no water in the unit while firing.
Corrective action:
This is an unlikely situation while all the safeties for checking the water presence didn't detect anything. Only
a lot of air in the system/unit (under pressure) can cause the water pressure switch to switch while no water
is present. Also the water leak detection
did not react. Bleed all air from the unit so the heat from combustion can be transferred to the water and
won't leave through the flue system.
Cause:
Heat exchanger failure.
Corrective action:
This is an unlikely situation but when there is severe damage to the heat exchanger, the combustion product
will not be able to transfer all heat to the system water. The heat that is not transferred will convert to an
increased flue gas temperature.
F
l
u
e
s
e
p
u m p
o
n
Flue sensor is not detected by the water heater PCB.
F
l
u
e
t
e m p
p
u m p
o
n
Flue gas temperature exceeded three times the limitation value within a certain
period.
n
s
o
r
e
r
9
9
9
t
o
o
9
9
9
r
o
r
,
5
h
r
s
h
i
g
h
,
5
h
r
s
102
Advertisement
Table of Contents
