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F15
Reason:
Cause:
The thermal fuse of the heat exchanger has opened permanently.
Corrective action:
Switch off the electrical power and gas supply and contact supplier.
Display message
F17
Reason:
Cause:
The water flow is restricted.
Corrective action:
Check functioning of the pump.
Check/open all valves that might restrict the water flow through the unit.
Check for an external system pump that influences the flow through the unit.
Check if the system resistance exceeds the spare capacity of the unit pump.
Display message
F18
Reason
Cause:
The fan of the non-burning burner is not able to run to prevent recirculation.
Check the 4 wired wiring and connections at the fan and at the main control board.
Check the 3 wired power supply wiring and connections at both ends.
Replace the fan.
Replace the main control board of that specific burner.
Cause:
It is not certain that the non-return valve of the burner, that is not burning, is closed.
Corrective action:
Check the state of the Non Return Valve:
> Is the valve moving freely to the open and closed positions.
> Is there debris/fouling or corrosion in the valve to prevent the valve to move freely.
Display message
F19
Reason:
Cause:
There is too much resistance in the flue gas circuit causing high pressure in the heat exchanger at the flue gas
side.
Corrective action:
Check if the flue gas system is blocked.
Extreme fouling of the heat exchanger also causes the resistance to rise. Check the state of the heat exchanger
and clean if necessary.
Check the flue gas system diameter & length (most likely in a new system).
C
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Heat exchanger fuse exceeded maximum value.
W a
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o
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Maximum thermostat exceeds limitation value.
A
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Air pressure switch activated for a certain time.
Or combination of NRV blocking and an F11 lock-out.
S
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u m p
o
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Siphon pressure switch detects high pressure in the flue/siphon system.
F
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,
5
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,
5
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is continued
F19
106
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