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  1. #1

    Rheem Modulating Furnace

    I have a problem and am hoping someone else has ran into this.
    I have a Rheem modulating natural gas furnace that fails intermittently, however I have never been able to catch it in the act,HO says that it does not fire, although it does display the H on the board signifying it is receiving a call from W for heat and a modulating call at V. Talked to the Rheem distributors factory trained tech (supposedly) and was told to replace the control board, so I did that and am receiving the same result. When it should be heating nothing at all happens it just runs on continuous fan. I have checked all of the wiring thoroughly so I know there is not a short somewhere. Please help!

  2. #2
    Typically continuous fan on a call for w is caused by an open limit switch. Try wiggling connectors while the furnace is running and see what happens.
    Alot of times I've also found intermittent issues were related to pressure switches opening briefly. Make sure all the ports are clear and inspect the condensation line if it's a 90%. Also check for proper flue size. Typically over 100,000 btu needs a 3" flue.

  3. #3
    Sorry I didn't explain it well, it runs on continuous fan from the call at the thermostat, if I turn the fan to auto it shuts the fan off. It is a 90% and I have checked all of those things, everything is clear on the pressure switch and drain end and the flu is 3" and only about 15 feet long, I have checked everything that would be considered a common issue I think it has to be something specific to this model.

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