Easy DIY Fix for a Broken Water Heater

Easy DIY Fix for a Broken Water Heater

No hot water? Before you call in the professionals grab your tools and head for the basement!

Exactly one week ago the hot water heater gave up the ghost. With house guests coming and a very long list of bad plumbers, it seemed wise to head into the basement to see what was what. Behind boxes, bags, and my son’s old hobbyhorse, there was the water heater. Within about ten minutes I realized that the water heater’s pilot light wouldn’t hold its flame. Luckily, years ago I had watched my father fix this problem so I set to work and so can you!


The Nuts and Bolts of Water Heaters


A gas powered water heater turns on and off using a pilot light just like a gas stove. In addition to the thermostat, there is an additional safety feature known as a thermocouple. This is a long thin metal device that generates a small electrical current when it is heated by the pilot flame. When the thermocouple is doing its job properly it keep the gas valve open to power the water heater. If for some reason the pilot light goes out on its own the thermocouple activates the safety valve to the gas supply line. Unfortunately, thermocouples can have relatively short life spans.


Should the pilot light to your hot water heater go out unexpectedly and no matter how long you hold the button down it refused to relight- a defective thermocouple is likely the culprit. This is the bad news. The good news is that replacing a thermocouple is within the ability of most homeowners.


1. First, turn the gas and the water heater off. At this stage or at any other stage of the repair if you smell gas turn off the main gas line and call a licensed plumber immediately. The smell of gas indicates that more than the thermocouple is defective!


2. After turning the water heater off, using a wrench or a pair of pliers remove the thermocouple from under the small exterior control housing on the outside of the water heater. The wire will look like a thick electrical wire and it is usually attached to the left side of the control knob as you look at the water heater.


3. Carefully pull the thermocouple gently out though the pilot light housing. Take a close look at the location of the old thermocouple before proceeding. A quick digital photo is not a bad idea before removing the thermocouple. Then measure it end to end with a tape measure.


4. Take the old thermocouple with you to a hardware store or a home center and match it up with one that is exactly the same size. Thermocouples are measured in length (16, 18, 24 inches). Buy the same size as the one you have removed from your water heater. The average thermocouple is $10.00. I paid $11.26 including tax.


5. Carefully push the new thermocouple back through the pilot light holder until it is in exactly the same position as the old one. Then screw the other end of the thermocouple back onto the water heater.


6. Turn the gas back on and relight the pilot light. If the thermocouple was the problem, the pilot light should stay lit. Check the coupling on the bottom of the control panel for gas leaks by rubbing some dish soap at the joint. If it bubbles, tighten the joint gently with a wrench until the bubbling stops.


7. Return both the outer and inner safety doors to the water heater, wait an hour and then enjoy a nice hot bath!




  1. one
    Comment by John@??? ???: May 2, 2012 at 4:35 AM

    Great guide here! Although I’m far from being a technical guy, I’m about to try this on an old heater that I own.

  2. two
    Comment by Jamison@mygasfireplacerepair.com: May 31, 2012 at 10:49 AM

    I love sites like these. Anytime we can fix something ourselves, we can save a costly service call. Nicely done!

  3. three
    Comment by Bob: Jun 22, 2012 at 3:19 PM

    great fix and this is easy to do. A plumber would charge you a fortune.

  4. four
    Comment by Joel@keywordluv: Jun 25, 2012 at 6:39 PM

    When the pilot is lit the flame is way bigger when is attempts to heat you the tank then before I changed it and the gas sounds louder?

  5. five
    Comment by Joel@keywordluv: Jun 25, 2012 at 6:43 PM

    Let me rephrase that last comment: I changed the thermocouple and noticed that the flame when it attempts to light is way bigger the flame come outside the tanks. Also I can hear a gas hissing more then before!
    What should I do?

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