Replacing a thermocouple is relatively easy, you only need to know how to use a wrench and have a new thermocouple to replace your old one. A thermocouple is very cheap and easy to buy on Amazon such as the Honeywell 24-Inch Replacement Thermocouple which should work just fine but check the size, length and specifications of your old thermocouple before buying a replacement!
- Turn the gas shut off valve to the water heater to the “off” position before starting
- Turn off the control and shutoff valves on the water heater
- Remove the burner access covers
- Loosen the nuts that secure the gas, pilot and thermocouple pipes
- Remove the pilot light assembly and replace the old thermocouple with a new one
- Re-insert the assembly, reattach the pipes and replace everything as it was
This replacement can be difficult to perform on some gas water heaters as they have an enclosed burner chamber. If you find that this is the case with yours, it’s better to call a pro to handle the task.
You also should not smell gas during this operation except briefly when you have removed the gas pipe. You should also use soapy water around the nuts when you have put everything back together so that the bubbles produced give away any leaks.
If you do smell continuous gas or are suspicious of a leak you should immediately call your utility company. Even though replacing the thermocouple is a simple procedure, if you are unsure of your ability to do this at all, it’s still better to have a service professional to do it just to be safe.
After the thermocouple replacement is complete you should find that your pilot light stays lit now and you should have no problems with your hot water unless there are other underlying issues with your water heater.