water heater pilot light won't stay lit

September 20, 2006 6:17 PM

Our water heater pilot light won't stay lit. Is it time to call a repair man?

Just this morning, with no warning, the pilot light on our water heater went out. Yes, I hold down the little button and press the other little button, and the pilot light fires up. Yup, I hold the little button down for a minute (or more). But when I let go of the button, the light goes out. Do I need to make the dreaded call, or is there something I can do myself?

posted by MrMoonPie to Home & Garden (9 answers total)

Yes call, the thermocouple is shot. It's a cheap repair.
posted by arse_hat at 6:34 PM on September 20, 2006

Unless you're out of gas, but if you're on city gas then yeah you probably need a new thermocouple.
posted by jessamyn at 6:56 PM on September 20, 2006

Best answer: Just a bit of expansion on what the others have said. The thermocouple is a safety device that turns off the gas if there is no pilot light. If you look closely at the burning pilot light, there is a small metal tube that sits directly in the flame, with wires that lead back to the gas valve. The thermocouple generates a small amount of electrical current when heated by the flame. This current keeps the gas safety valve open. If the pilot light gets blown out, the current stops and the gas valve closes. When you light the pilot light, you hold down the over-ride button for about 30 seconds. This allows the gas to flow long enough to heat up the thermocouple and generate current and then you can release the over-ride button and gas will continue to flow. If the thermocouple is defective, then as soon as you release the over-ride button, since there is no electrical current, the gas will stop flowing and the pilot light will go out.

This is a pretty common failure on water heaters and furnaces. Replacement of the thermocouple is fairly simple if you are the handyman type. If not, the thermocouple is a cheap part -- about $10 bucks, but the service call may run you $100 or so. Before you call a serviceman, get all of the brand and model information from the information plate on the heater so he can bring the proper replacement part.
posted by JackFlash at 7:44 PM on September 20, 2006

Best answer: Yes, It is in all probability the thermocouple as described by JackFlash above. There are only a limited number of types commonly in use so getting a replacement should be simple. Replacement takes just a few minutes and generally requires nothing more than a small adjustable wrench (spanner). A Google search for 'thermocouple replacement' should produce a well illustrated DIY article.

I'd recommend removing the old thermocouple and taking it to the hardware store to get a matching replacement. You might want to take a couple of pictures before taking anything apart to have as reference when you install the new one.
posted by X4ster at 8:18 PM on September 20, 2006

One other thought. Do you own the water heater? Anywhere I have lived with gas hot water the tank was a rental. Check your gas bill. If it is a rental then the replacement will cost you nothing.
posted by arse_hat at 10:30 PM on September 20, 2006

Keeping arse_hat's rider in mind, I think that X4star has it right. The replacement is quite simple (turn off the gas first) and if you screw it up (pretty hard to do really), it's not going to be a problem for any professional that you call. to fix. If you don't screw it up -you'll have saved yourself $100 or more.
posted by Neiltupper at 11:18 PM on September 20, 2006

Response by poster: Thanks for the information, all. I Googled "thermocouple replacement whirlpool," and was interested to see what came up as the first hit. The second hit included a link to clear repair instructions, which I'm about to attempt to follow. Thanks, AskMetafilter!
posted by MrMoonPie at 5:09 AM on September 21, 2006

I had the same problem after someone installed a new gas heater in my house, it turns they reinstalled the vent pipe to close to the heater thus not letting it vent properly. I separated it, and that did the trick.
Good Luck
posted by FLHunter3006 at 10:19 AM on September 21, 2006

Response by poster: We have hot water! Yay, AskMetafilter!
posted by MrMoonPie at 10:50 AM on September 21, 2006