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Water Heater Flame out: offset thermocouple or bad ones?

Hi folks,

My water heater's flame keeps dying out over the weekend. I was able to relit it yesterday but it won't stay on over few hours. Today I cannot light it at all. The flame comes up when I press the ignite button but goes out as soon as I release the pilot button.

I have looked up closely on the flame position and it looks like to me that the flame does not touch the thermocouple at all. Understandably not holding pilot flame in place.

One thing I noticed: When I was able to light the flame yesterday, after turning the thermostat to HOT position, the big flame first turned orange-ish and seemed to burn off some dust. It then turned back to normal blue so I just ignored it. Was it burning off the tip of the thermocouple?

The water heater is: RUUD prog50 38n, installed on 2020. Unfortunately their warranty does not transfer to new owners.

I am a complete noob on this so I hope to get the theory checked out by you experienced folks before I run out to get a new thermocouple /open up the heater.

Did my best on the picture focus. Thanks a ton.


  • crazyFrog
    crazyFrog Member Posts: 2
    My complete theories are:
    1. Thermocouple not contacting flame -> reposition it or replace it if tip burnt out
    2. Thermocouple dirty -> clean it
    3. Thermocouple failed -> replace it
    4. Problems with the thermo-control -> hire professionals...
  • Jamie Hall
    Jamie Hall Member Posts: 23,567
    To which I will add: that's a pretty feeble looking pilot flame. How is your gas pressure?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,364
    edited February 2022
    Hi @crazyFrog , There are a few things you can do depending on your skill and what tools you have. Moving things so the thermocouple is in the flame would be a good start. It's not all that clear to me from the picture where things are. Testing the thermocouple by heating the tip and measuring millivolts at the other end will let you know if it works. I like to see the thermocouple tip heated to a dark red. This happens when the flame wraps at least half way around it. The pilot flame often is so low because the pilot orifice gets dirty and reduces gas flow, so often, cleaning the pilot orifice fixes things. If all of that fails, you may have a defective gas control valve. Hope that helps!

    Yours, Larry

    ps, If it's in a dusty environment, the air inlet screening might be partly clogged up. When you get it to fire up, watch the main burner flame. Is it solid, mostly blue and not lifting up off of the burner? Or is it a lazy flame that rises up off the burner? If there is insufficient combustion air, you'll see something more like the latter, meaning the burner has to come out and the floor of the combustion chamber blown out and vacuumed. Also, is there any flashing light... error code on the control?
  • Jon_blaney
    Jon_blaney Member Posts: 321
    What brand water heater is it? There are some Youtube videos about bad gas valves. Rudd and Rheam I think.
  • wmgeorge
    wmgeorge Member Posts: 222
    edited February 2022
    Adjust the pilot flame a bit, perhaps a 1/4 ccw turn at the most. Should be a very small screwdriver slot, may or may not have a cap over it. Tiny. No other adjustments!!
    Any serviceman should be able to handle, they carry thermocouples in there truck, at least I did anyway.
    Old retired Commercial HVAC/R guy in Iowa. Master electrician.