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Why is this happening?

Ken C.
Ken C. Member Posts: 267
in THE MAIN WALL
in an apartment complex. Each unit has a gas-fired, wall-hung, direct vent boiler with an indirect water heater. The unit is a Potterton Netaheat (made in England). On a call for heat or hot water, the vent fan turns on and the spark ignition will light the pilot, but the burner fails to come on. However, if the boiler's cover is removed, the burners will then come on. The cover has gaskets that prevent the boiler from using room air for combustion. I checked the exhaust vent for blockage (i.e., bird's nest), it was clear. I checked the boiler heat exchanger for possible soot blockage, but the flue passages were clean. The pilot flame is strong and making good contact with the mercury switch (which looks and functions like a thermocouple). Why would the burner come on only when the boiler's cover is removed? I'm not sure what to check next.

Comments

  • Ken_8
    Ken_8 Member Posts: 1,640
    Air proving

    switch

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  • marc
    marc Member Posts: 203
    did you check

    the intake pipe, sounds like a sealed combustion unit, is the vent concentric, try disconnecting the vent or jumping pressure switch to see if the unit will fire, is this with 1 unit or all of them, marc
  • Weezbo
    Weezbo Member Posts: 6,232
    a safety switch...

  • Dingo
    Dingo Member Posts: 38
    ODS ... ?

    Just my quick thought

    Dingo
  • Ken C.
    Ken C. Member Posts: 267
    What does ODS stand for?

  • Ken C.
    Ken C. Member Posts: 267
    Yes, it is sealed combustion

    Because of the configuration of the unit, I cannot easily disconnect the vent. I will try jumping out the pressure switch, though.
  • Unknown
    Unknown
    No ODS on this unit

    Oxygen Depletion Safety devices not used on Potterton Netaheat.

    Ken remove the pilot and clean the pilot. You are getting a different air mix with the cover off that is why it works. You have to get that mercury sensor chery red. You will be suprised if you clean the pilot it will work.

    Come to school we will teach you all about these units.

    If cleaning the pilot does not work I will dig out my notes on that unit and see if there may be another possibility.
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