Rheem tankless water heater, unusual behaviour

Discussion in 'Tankless Water Heater Forum' started by Ron A Goldberg, Jul 21, 2019.

  1. Ron A Goldberg

    Ron A Goldberg New Member

    Jul 21, 2019
    New Orleans
    Hello All,
    This is my first time posting.
    My 4 gallon tankless water heater started having intermittent issues not getting lit and giving me error 11.

    After going through a number of trouble shooting the resistance of the electronics and replacing the flame rods and sensors, and cleaning the burner section I'm still getting the error.

    If I follow the procedure I'll post below it will run.
    01 Turn off the gas valve and run water till I get the error message #11.
    02 Then turn off the water, turn the gas valve back on and run water again it will stay hot and operate correctly.

    As long as the water is running the water heater functions correctly.
    Once I turn the water off I have to stayrt the process over again but it appears to work.

    Any idea what's going on?

    That's for your help.
    Last edited: Jul 21, 2019
  2. Tankless Tech

    Tankless Tech New Member

    Jun 12, 2019
    North Little Rock, Arkansas
    Error code 11 means the flame rod(s) do not detect any flame.

    Sounds like a gas issue. If you have already cleaned the burner, checked wiring resistance and replaced the flame rods you need to check the gas pressure using a manometer by unscrewing the screw on the gas inlet bottom right of heater and hooking the hose on the manometer up there to take your reading. What size is the gas supply line?

    If the gas pressure is too low it wont be enough to ignite. If it is too high it also wont light. depending on the model there is a range of inches water column that is specified in the handbook and trouble shooting guide.

    What is the model number of the heater?
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