116
Display message
F l u e
t e m p
h i g h
9 9 9 , 5
h r s
Reason
Flue gas temperature has exceeded the limit.
Cause:
Heat exchanger polluted and not able to transfer enough heat to the 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 that the resistance lowers when the tempera-
ture rises. A partly shorted sensor will drop its
resistance and therefore ‘measure’ a rise in
temperature when actually there is none.
Check for moist in the sensor connections or replace the 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.
Display message
G e n
B l o c k
9 9 9 , 5
h r s
Reason
General blocking circuit is activated during operation (general
blocking contacts 7-8).
Cause:
The circuit connected to the general blocking terminals is not closed.
Corrective action:
Check all external components that are connected to the general blocking terminals and
check why the contact is not closing during heat demand.
Cause: If used in combination with flow switch:
The water flow through the unit is too low.
Corrective action:
Check functioning of the pump and the flow switch.
Check/open all valves that might restrict the water flow through the unit.
Check for an external system pump that influences flow through the unit.
Check if the system resistance exceeds the spare capacity of the unit pump.
Make sure the heat exchanger is clean. Heat exchanger fouling (partly blockage) will in-
crease the resistance causing the water flow to drop
