Water Heaters - Is it a thermocouple problem?

Hello All.

I've been reading all of the back posts trying to figure out my problem and it seems as though anytime the gas water heater pilot light is going out it is the thermocouple that needs to be replaced. I think I can do that myself, after reading everything, but I want to give you my sccenario to affirm it probably IS the thermocouple.

The water heater is a 40 gallon 2002 Whirpool. I have been living here for the last year and a half with NO problems whatsoever. This morning I went to take a bath before Church and there was no hot water. I checked the water heater and saw the pilot was off. I read the instructions and reset the light thinking I was genius :) Thirty minutes later, no hot water. The pilot was OFF. I reset it and sat there and stared at it. After 15 minutes it went off. I reset it and after 5 minutes it went off. Does this sound like the thermocouple to you? The majority of the posts I read said the pilot "wouldn't stay lit" but I don't know if they mean for 1 minute or like mine, would lite for ten minutes and then go off.

Thank you so much for your replies - I have missed Church AND I'm stinky!

Thanks!

Sounds like you already have two strikes against you, missing church and being stinky. Fear not, we'll figure out what the problem is.

First, lets make sure that when you lit the pilot, you hold the knob in for 30 second to a minute and it stays lit when you let go of the button. Furthermore, it stays lit when you turn the gas control knob to on. CAUTION: Never keep your face near the combustion chamber when you turn the control knob on or turn up the thermostat. If there is any build up of gas that ignites, you will get burnt!

Now that we are sure you are lighting it properly, is the water heater a "Flame Lock" model or not? If it is a Flame Lock model, there will be a small sight glass to see the pilot. If it's not, then you can just pull off the cover and see inside the chamber.

If you heater is going out after a minute or so, it sounds as if the thermocouple is going bad as it's not generating enough voltage to keep the gas valve open.

If you could reply back with the model # in a future post, it will help determine if it's a Flame Lock model heater.

Hi Hank,

Thanks so much for trying to help me. It IS the dreaded Flame Lock because it has that little port window/shield on the front. It is a 2002 model and the model# is
FGIF4040S3NOV.

I was lighting the pilot as you said, and it WILL stay lit for the 5 - 15 minutes. That's what caused me to post here to see if you experts thought it was actually the thermocouple, because it seemed like it was trying to heat the water but then just got a bit "confused"... and turned the burner/pilot off. I didn't know if the thermocouple would do that or if it was turning itself off during the "water heating" period due to some faulty thermostat or something.

Thanks so much!

Stinky in San Antone...

if your in the pilot position on the gas valve and the pilot stays lit....then you turn the dial to ON,and the pilot goes out it is the thermal couple.its not producing the milivolts from the pilot fllame to hold the pilot open,and to proof the main burner when you go to ON

Since it does work for a short period I think I would make sure the the arrestor plate is not plugged with lint. The arrestor plate is located under the water heater and allows combustion air to enter the combustion area. Try taking a brush and clean from the bottom. If you just happen to have an air compressor all the better.
If you do need a thermocouple that vintage uses a left-hand model that incorporates a fuse link safety. You might try calling the mfg. At one time I understand they would send out a new burner assembly and an adapter for the left-hand thermocouple that converted to right-hand.

Dear Sminker,

Thanks for replying.

When I turn the gas valve to "ON" the burners DO light up every time, but they will go off in 15 or so minutes. I honestly have sat there staring at it (while wishing I had the good sense to date a plumber) ... and it seems like when it "thinks" it is hot water, it just shuts itself down. I hear an audible "click" and the whole thing - pilot & Burners - shut off.

Do you still think it is the thermocouple?
:rolleyes:
THANKS VERY MUCH.

Arrestor plate? Who knew. Thanks for telling me it's underneath, that'll save me another hour of research! I will clean it out tomorrow morning when I am repeatedly reliting the pilot trying to get hot water for my kiddos to take a bath in before school. Thanks for the suggestion ;)

the main burner coming on might be blowing the pilot out...if the pilot stays lit with the gas valve dial in the PILOT position the thermal couple is OK..the only way to do a test is to leave the gas valve in PILOT positon all day when your at work to see on the return home if it is still lit.the pilot should cover the top of the thermal couple if it isn't that could cause that 15 minute on/off deal ...depending on the design on the burner don't think the main gas being on will keep the thermal couple hot so the main burner continues to heat.the pilot should be strong like what you see on the stove burners

Mbk3 beat me to the punch. Check the arrestor plate. With this blocked will snuff out the burner and pilot due to lack of air in the combustion chamber.

Since you can relight the pilot each time the thermocouple is likely ok. If the bulb overheats, it has to be changes. BTW, changing one of those thermocouples is a big pain.