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Power Vent Water Heater not firing.

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  • Power Vent Water Heater not firing.

    I don't see too many "American" Power venting water heaters. This weekend I was on a service call where the "hot water was cold". When I checked the heater, it was a 40 gallon, 50,000 btuh natural gas fired power vented water heater. It wasn't leaking water and the pilot light was lit. (Usually when I get "cold" hot water calls on power vent water heaters the problem is a dirty flame sensor but not in this case, as it had a standing pilot.)

    Interestingly there was another gas orifice located just above the pilot light assembly, but which was definitely not the main burner. When the thermostat was located so it called for heat gas came out of this orifice and the pilot ignited it. When this happened, the main burner did not ignite. "American" technical assistance stated this orifice is simply "extra" gas being vented from the gas valve.

    But I digress, the problem was the main burner would not ignite. The fan has a pressure switch on it to verify that the fan is operational and functioning. The gas valve won't get power to turn on untill the pressure switch closes. According to "American" technical assistance the usual cause is dust clogging the outlet port on the fan. Using a paper clip cleared the dust. The water heater fired satisfactorily afterward.

    Pict 1 is the water heater shoehorned into a ridiculously small area.
    Pic 2 is obvious. You can see the extra orifice.
    pic 3 is the pilot only lit.
    pic 4 is the vented gas orifice lit
    pic 5 is the port on the top of the fan where the paper clip is inserted to clear the dust, see the red arrow. (I never actually saw the port, it was behind the fan assembly, I did everything by feel, and just snapped the picture blind.)

    American's technical assistance was great. I thought I would call just in case someone would answer on a late Saturday afternoon. They provided the info for a quick fix!
    Attached Files
    Last edited by geno gardner; 10-25-2010, 09:34 PM.
    Time flies like an arrow.

    Fruit flies like a banana.

  • #2
    Re: Power Vent Water Heater not firing.

    I ran into that same problem before on a Bradford white.

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    • #3
      Re: Power Vent Water Heater not firing.

      That last pic. needs a vacuum to clean it up bad

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      • #4
        Re: Power Vent Water Heater not firing.

        Originally posted by DELCASE View Post
        That last pic. needs a vacuum to clean it up bad
        Good call. I used a shop vac.

        It's going to be a big mess when that heater fails someday. Carpet all around it, and no disaster pan. I'm not sure the heater will come out sans violence.
        Time flies like an arrow.

        Fruit flies like a banana.

        Comment

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