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Removing the flame sensor on Rinnai E50

nibs Member Posts: 516
Tech at Rinnai tell me to remove & clean the flame sensing rod on my almost new E50C.
I can see no threads, and no flats, just the ceramic(?) end with the wire connection.
Getting the dreaded E 02 error.
After 2 months in service and 5 months after startup this is a bit scary and we hope not a harbinger of things to come.
Thanks in advance,


  • nibs
    nibs Member Posts: 516
    In answer to my question; the sight glass, igniter, ground and flame sensor are all mounted on a plate that is held in at each end by spring clips.
  • psb75
    psb75 Member Posts: 845
    I have an E50C in service for 4 yrs now. Dealt w/ Rinnai Tech support to find out it was sensitive to U.S. lower pressure settings of 14 psi. I raised system pressure and solved problem. Boiler would go into de-aeration program and DHW would "cut-out" when user was showering.
    Your E-02 code: fuel supply issues? I've had this in very cold winter with LP regulator freezing up. Heat gun fixed that.
    Rinnai tech support is generally pretty good.
  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 4,052
    edited May 2019
    I'm sorry that you are having troubles with your Rinnai since I'm the one that recommended it.
    Most if not all of the new generation of boilers are very sensitive to fuel supply conditions. If you're on natural gas, the pressure has to be between 7" - 10" W.C. when the boiler is off with a minimum of 3" when the boiler is firing. Personally, I don't like to see more that a 1" pressure drop when the boiler fires. If the pressure drops too much, it's an indication that the pipe size is too small or the gas regulator is out of whack.
    And yes, continue to work with Rinnai tech. support until you find the solution. If you don't have a manometer, you may need to find a tech. that has one to check your gas pressures.
    The 17 minute de-aeration process that happens every time you turn the boiler off and then on again is a drag. The work-around is:
    Push the "Mode" button for 5 seconds.
    "C" and a number will show, push the up button until the number 123 shows.
    Push the snowflake button to store.
    Push the reset button.

    Good luck and let us know what happens!
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • nibs
    nibs Member Posts: 516
    Thanks to all, turns out that it was the ionizing wire (flame sensor) may not have been pressed all the way in to the circuit board and went open, found it, fixed it, and life is good.