Atwood 7916 Heater problem

Discussion in 'Heating / Cooling Systems' started by samwise, Jun 7, 2019.

  1. samwise

    samwise New Member

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    We own a 2011 Coleman Sedona, which has the Atwood 7916-ii heater. On our last camping trip, it kept acting up. It would run for a few hours and then suddenly start having problems, where it would just quit in the middle of the heating cycle, without cycling out the heat (fan on, burner off). It blinked one red light every three seconds which I understand is the code for a limit/air flow problem. I was able to push the reset button on the furnace and cycle down he thermostat. That seemed to reset it and let it run a few more hours. I'll also add we were running on battery at the time.

    I had the circuit board tested at a local RV shop and it came back great. I've replaced the limit switch and am working on the sail switch. There is virtually no dust, dirt, or anything else in the furnace. We store it in our garage during the winter.

    My conclusion is that the battery got below the necessary 10.5 volts on a draw from the motor. The battery is over three years old and did sit in our garage in Colorado during the winter. I did charge it a few times with a battery tender. It did test okay a the battery shop, but went down to 10 volts on draw (Which is right on the edge of their cut off for a good battery).

    Anything else you can think might be wrong? We leave next week for a trip and I'd love to have heat. Thanks!
     
  2. tim kinser

    tim kinser New Member

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    Personally I would thoroughly check inside the heat exchanger to make sure bees, wasps or even a mouse hasn't built a nest in there or even the vent tube. It sounds like something may be partially blocking the excess heat from escaping causing the limit switch to trip. Some are self resetting which will allow the furnace to turn back on. Just in case you are un aware the limit switch detects excessive heat in the heat exchanger and shuts the whole system down when there is a problem. The heat exchanger itself can be very difficult to see inside. Maybe a long flexible pipe cleaner and a shop vac?
     
  3. samwise

    samwise New Member

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    I am aware of the limit switch's function. I believe it works in series with the sail switch, shutting off the system for too little air flow or too much heat. I did pull the whole heater and did not find anything inside. But I'll try shop vac-ing just incase.
     
  4. Sjm9911

    Sjm9911 Well-Known Member

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    A limit switch, at least on residential units is just for heat, after they reach the heat limit they shut off. They go bad constantly. Air flow, rain , flue not drafting properly, down drafts etc can set one off. They , at least on residential units, are resetable. If the code was for a limit switch ,i would look at that and the flue. No need to look for other stuff. Easy way to tall is to just bypass it. See if it runs or not.
     
  5. neighbormike

    neighbormike Well-Known Member

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    What was the battery voltage at the time the furnace acted up? Also, does the problem occur when on shore power? or just battery??
     
    theseus likes this.

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