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Gas Wall Heater Turning On and Off

AlexM Member Posts: 1
Hi there,

We have a gas wall heater and we have been having episodes (typically at night) where the thermostat shows the temperature is below the desired temperature and the unit ignites (turns on) and runs for a couple minutes and then shuts off for about 30-45 seconds, then turns on again, runs for a couple minutes, and then turns off again. During these episodes, the thermostat is not responsive (ie, if I try to turn up the temperature

to restart the heater after it turns off, it will not start up right away).

We have tried turning off the unit and waiting a few hours and then it seems to respond to the thermostat again and will run for a good amount of time without turning off. So, the issue is intermittent, but seems to happen at night when the unit has been supposed to be running for a few hours.

Additionally, we have found a few small black flakes of soot on the carpet by the heater.

The second issue is a loud metallic bang that happens about 30 seconds after the unit turns on and then much louder when the until turns off and cools for about 10 minutes. The bang is a single, loud metallic bang. When it is the cooling noise, it is loud enough to scare you or wake up a sleeping baby.

The turning on/turning off started just after we had the heater cleaned and serviced. I had the same techs who cleaned it out come out after we started having the problem and the unit turned on and stayed on (but it was cold, we had turned it off after it was cycling all night). They checked the voltage and couldn't find anything wrong. I am now going to call a second company, but was hoping I could get a few ideas here before another company gets involved. Thanks for any help or ideas.


  • unclejohn
    unclejohn Member Posts: 1,833
    When you say

    The furnace turns on [ignites]and then off and restarts. Are the burners going on and off or just the blower? The soot is a very bad thing. A properly operating burner will not make soot. I would keep it off untill some one takes another look at it.
  • VictoriaEnergy
    VictoriaEnergy Member Posts: 126
    I agree...

    I agree with unclejohn.  Don't use it until it is serviced.

    Sooting is an indication the burner could be starved for air, this means the exhaust will have very high levels of carbon monoxide in it.

    A new Oil canning noise,  (expansion noises from the heat exchanger buckling); could indicate the heat exchanger is cracked, blocked or falling apart.

    So it is possible you have a dangerous situation with exhaust entering the house..

    It would be helpful to know the make and model of the heater too. 

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