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Dunkirk 95M-200 (& controller) needs to be powered down to re-fire

dank Member Posts: 2
We have a 7-year-old Dunkirk 95M-200 high-efficiency boiler. All of a sudden it will hit the target temp (150) and then over a couple of hours the output temp will drift down to room temp (66, as the rooms get cold).

- It cycles through the various modes on the way to 150 degrees, so it will re-ignite then.
- It will not re-ignite after turning off just the unit (using the switch on the front panel) ... it powers up and goes to Mode 0
- It will only re-ignite when I turn off both the boiler and the control box which has the relays which "call" for the hot water for the 2 zones/hot water tank.
- During the time when the output water temp is dropping, the HVAC system seems to be calling for hot water, as does the water tank (the devices are on and the LEDs on the control box are lit green, which is what they are lit when they call for hot water).



  • unclejohn
    unclejohn Member Posts: 1,833
    May need just a maintenance call. To many things could be bad to guess at. Dirty flame sensor pressure switch broken hose.
  • dank
    dank Member Posts: 2
    Turned out to be a faulty relay on the external controller.