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Rheem HW Heater won’t light

Slowhand63
Slowhand63 Member Posts: 80
in Domestic Hot Water
Woke up to no HW.  Rheem 50g HW heater just over a year old.  I can light the pilot light by holding down the button - stays lit while I’m holding the button down.  To turn the knob to “on” I need to release the button.  As soon as I do the pilot light goes out.  

I’m thinking it’s the thermocouple, but could also be the gas valve, or ?  Appreciate any suggestions or things I can check. If it’s a thermocouple, any diagrams or photos on how to replace would be appreciated.  

Comments

  • Zman
    Zman Member Posts: 7,611
    How does the pilot flame around the thermocouple look?
    It is probably a bad thermocouple.
    Replacement varies by model.
    Got pictures? Especially the flame.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • unclejohn
    unclejohn Member Posts: 1,833
    edited March 2021
    All the new heaters I see have a push button spark igniter. When the pilot lites a light will blink. Are you sure about the one year old.
  • Slowhand63
    Slowhand63 Member Posts: 80
    Thanks for the comments on my post. I’d say the flame was unimpressive - smaller than expected, small blue cone about 1/2 - 3/4” high. The push button spark generator works 50-75% of the time, but a few snaps and it lights the pilot. The pilot will stay lit as long as I keep the button pressed. After doing some additional research I’m guessing the thermocouple. Also cheapest and easiest to change. Does anyone know if a universal (Home Depot) thermocouple will work? I’ve read posts that suggest only one from Rheem will work. Also - the system is “closed” - any concerns re the gasket or should it be okay to simply remove the screws and then replace? Thx
  • mattmia2
    mattmia2 Member Posts: 10,933
    How long did you hold the button? I think some of the fancy ones with blinky lights use a thermopile to generate enough power for the control. I don't think there are any gaskets, just a screen to keep a flame from spreading to flammable vapors outside the combustion chamber.
  • Slowhand63
    Slowhand63 Member Posts: 80
    I held the button for 90 seconds or more.
  • mattmia2
    mattmia2 Member Posts: 10,933
    Most likely the thermocouple. there us a way to check it with a voltmeter
  • Slowhand63
    Slowhand63 Member Posts: 80
    Does anyone know if a universal thermocouple will work on a Rheem?
  • mattmia2
    mattmia2 Member Posts: 10,933
    Depends on the valve. Probably if it uses a standard coaxial type thermocouple. Rheem has made hundreds of millions of water heaters. The usually bought the valve from someone else.
  • psb75
    psb75 Member Posts: 906
    Thermocouples are "consumable" items. Unusual for a one-yr.-old one to go bad. Just get a thermocouple of a similar length. In fact take out the old(bad) one and take it with you to the store in order to match it.
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,597
    Hi, A possible simple fix is to loosen and retighten the connection between thermocouple and gas valve. Sometimes that connection is loose or gets a bit of corrosion. Also, the pilot flame should make good contact with the thermocouple and make the tip glow a dark red. If it isn’t doing that, maybe some dust has gotten into the pilot orifice.

    Yours, Larry
    PC7060

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