Home Renovation Happenings
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Home Renovation Happenings

There is a lot to think about when you’re renovating a home. You need to make many decisions, starting with what contractor to use and how much money you want to spend. It helps if you have a clear vision for how you want your home to look when you’re done. If you’re not sure what it is that you want yet, take some time to look through my blog. I’ll discuss everything from home additions to flooring materials to appliances and fixtures. These articles will help you get a sense of the possibilities for your home renovation, and help you narrow down your options. Eventually, you’ll decide on the renovations that are right for you.

Home Renovation Happenings

DIY Repair: Replacing The Thermocouple In Your Gas Water Heater

Pamela Gonzales

There are a number of reasons why your water heater may suddenly stop producing hot water, but one of the most common causes is a bad thermocouple. If you've lit your pilot light numerous times but it won't stay on, then you may need to replace the appliance's thermocouple. Here's how to diagnose the problem and step by step instructions for completing this simple repair at home.

About Thermocouples

The purpose of the thermocouple device is to detect whether the pilot light is on or off and regulate the flow of gas to the appliance appropriately. It sends a signal to the gas valve to stay closed when the pilot light goes out to prevent gas from leaking into your home and causing a safety hazard.

Most of the older models and some newer ones have the standing pilot design where the thermocouple is connected to the burner assembly and control box. Newer models may have electronic ignition pilots where an electronic igniter is also attached to the burner assembly. There may also be a burner manifold cover plate.

Troubleshooting Thermocouple Problems

Before going through the trouble of diagnosing and replacing your thermocouple device, check your pilot light to make sure there isn't any debris in or around its mouth or in the tubing connecting the valve and pilot light. Sometimes small insects such as spiders will climb in these areas and cause clogs, particularly if the water heater hasn't been used in a long time. Use a thin piece of wire to clean the area or tube being careful not to scratch or enlarge the either the mouth or the tubing.

To confirm that the problem is the thermocouple, relight the pilot light according to the directions on your appliance. Be certain to hold the button a full 30-60 seconds to allow the thermocouple to heat up (this signals to the device that pilot is on). If the pilot light goes out immediately after you release the button, then the thermocouple needs to be repaired or replaced.

Repairing and Replacing the Thermocouple

Before purchasing a new thermocouple, inspect the probe. If the surface of the probe is white, then it is covered in carbon, which can prevent the device from sensing when the pilot light is on. Using a fine emery cloth, sand the carbon away and try to relight the pilot.

If the pilot still won't stay on then replace the thermocouple completely. Here are the step-by-step instructions on how to do that (here's an instructional video for visual learners):

  1. Before doing anything else, shut off the gas supply and turn the temperature down to the lowest setting.
  2. Using a small wrench with a smooth surface, gently remove the nuts connecting the thermocouple and gas tubes to the water heater control box. Pull to disconnect them from the box.
  3. Pull the entire burner unit from its storage slot. Knock off any rust or debris that may have accumulated on the burner. If you have an electronic igniter, then you'll need to burner assembly manifold before you can get to the burner itself.
  4. Thermocouples are typically connected to the burner unit via a compression slot, but sometimes they are clipped to it. Disconnect the old thermocouple, set it aside and connect the new one exactly as the old one was set up.  Thermocouples come in a variety of lengths, but don't worry if you get one that's too long. You can simply coil the device to a more manageable size when attaching it to the burner.
  5. Reinsert the burner into the slot (replace the manifold if applicable), push the pilot tubes and the thermocouple back into the control box. The material used to make these tubes is very soft, so you want to be very gentle when screwing the nuts back on.
  6. Reconnect the gas and turn the pilot light on.

If a burnt out thermocouple was the only problem affecting the pilot light, then it should start working normally. However, if the pilot light won't stay on or another problem manifests once you get the water heater working, then it's probably best to contact an experienced plumber from a place like Smedley & Associates, Plumbing, Heating, Air Conditioning for advice and assistance.