• Share:
Hot Water Problems? Restore It Yourself

Before you replace a broken hot water heater, check to make sure the thermocouple still works. It's a simple, inexpensive repair that could save you a bundle.

By the DIY experts of The Family Handyman Magazine

Diagnosing and fixing a thermocouple problem

Inside the burner compartment of your gas water heater, right in front of the pilot light, is a small metal cylinder called a thermocouple. The thermocouple is a safety device that senses when the pilot light is burning. If the pilot goes out, the thermocouple signals the gas valve to remain closed until the pilot light is relit.

When thermocouples wear out, the pilot light goes out, the burner won't light, and you don’t get any hot water. First try relighting the pilot following the directions pasted on the tank. If the pilot lights but the flame goes out as soon as you release the button after holding it for 60 seconds, then the thermocouple is bad.

It's possible to replace the thermocouple without removing the burner assembly, and many repair people do this. But removing the burner assembly as we've done simplifies the job of replacing the thermocouple and allows you to vacuum out the burner compartment and clean the burner while you're at it.

Even though this job is simple, don't attempt it unless you know how to turn off the gas to the water heater and are comfortable with relighting the pilot. You'll need a few wrenches to remove the burner, possibly a screwdriver to remove the access cover, and a small brush and dishwashing liquid to test for leaks.

Thermocouples for water heaters are readily available at hardware stores and home centers. Remove the old thermocouple and measure it. Then buy the same size replacement. Parts are included to mount the thermocouple in almost any water heater.

Call a repair person if your water heater looks different from the one shown.

Disconnect the old thermocouple

Refer to Photo 1 when disconnecting the thermocouple.

Insert the new thermocouple

Refer to photo 2 when replacing the old thermocouple.

Reinstall the burner and tighten the nuts

Refer to Photo 3 when reinstalling the burner

To Test for Leaks
  • Turn the temperature control to “Off.”
  • Open the lever handle gas valve to the water heater.
  • Light the pilot according to instructions on the water heater.
  • Replace the access covers.
  • Turn up the temperature control until the burner lights.
  • Test around the burner and pilot light connections with a solution of dishwashing liquid and water. The burner must be on to test the burner connections. If bubbles appear, shut off the gas and tighten the fittings. Then repeat this procedure. Shut off the gas and call a gas repair person if leaks continue.
Back to Top

Required Tools for this Project

Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.

    • Small paintbrush
    • Wrench set

Required Materials for this Project

Avoid last-minute shopping trips by having all your materials ready ahead of time. Here's a list.

    • Thermocouple

Comments from DIY Community Members

Share what's on your mind and see what other DIYers are thinking about.

1 - 4 of 4 comments
Show per page: 20   All

January 19, 8:21 PM [GMT -5]

my hot water heater is doing the same thing as dussiej and tjmach. Have yall found any solutions to this yet? I light it, it fills the tank, heats it up and then shuts off...the pilot goes out.

January 08, 3:34 PM [GMT -5]

I have the same problem as tjmach... tjmach, did you find out what the problem was?

December 30, 12:57 PM [GMT -5]

my question is: the pilot light stays lit once i let up the ignite button, and the water heater heats the water. but when it's done heating, the pilot light goes out

September 06, 6:04 PM [GMT -5]

This was one of the easiest DIY projects I've done. The directions say to remove all tubes/connections including taking out the burner. At least with my unit, the thermocouple was so easy to get to, that I was able to replace just this piece without touching anything else. Took about 5 mins.

+ Add Your Comment
closeX

Add Your Comment

Hot Water Problems? Restore It Yourself

Please add your comment
closeX

Log in to My Account

Log in to enjoy membership benefits from The Family Handyman.

  • Forgot your password?
Don’t have an account yet?

Sign up today for FREE and become part of The Family Handyman community of DIYers.

Member benefits:

  • Get a FREE Traditional Bookcase Project Plan
  • Sign up for FREE DIY newsletters
  • Save projects to your project binder
  • Ask and answer questions in our DIY Forums
  • Share comments on DIY Projects and more!
Join Us Today
closeX

Report Abuse

Subject
Reasons for reporting post

Free OnSite Newsletter

Get timely DIY projects for your home and yard, plus a dream project for your wish list!

Follow Us

Featured Product

Buy Now