How Thermocouples Work on Ones Oklahoma City Water Heater

Posted by on Dec 9, 2013 in Water Heater Repair Oklahoma City

Ok, not to get too technical with you today, but Water Heater Repair Oklahoma City wants to share some information on a water heater’s thermocouple.

The Family Handyman correctly concluded that “when thermocouples wear out, the pilot light goes out, the burner won’t light, and you don’t get any hot water.”

Conventional style
Also called universal water heater thermocouple. It screws into the bottom of the gas valve and a probe on the other end slides into a holding bracket near the pilot light. It looks like a piece of copper wire.

Universal thermocouples are available in lengths from 15 to 36 inches. An 18 or 24 inch will be enough for all domestic water heaters utilizing universal kits. Virtually all older waters heaters and numerous of the newer style systems with a covered burner compartment and a seeing window will use this thermocouple.
If you wish to use a precise replacement length just eliminate your old one and determine it.

TCO design

Thermal Cut Off design has a re-settable thermal turned off switch integral into the thermocouple. In case of a flash fire or blow back from the burner the TOC will shut down gas flow to the burner and pilot. In case of a closed down the TOC should reset itself after it cools off and permit you to relight the pilot. The TOC switch looks like a watch battery. You will only discover the TOC on more recent design water heaters with seal burner compartments.

TOC non-resettable style

These thermocouples have a tiny TOC build inside the tube. They look comparable to a conventional one other than the diameter is bigger about midways of television. When these TOC’s switch off they will not reset and need to be replaced.

How Thermocouples Work

A pilot thermocouple sends out a tiny electrical current to the gas valve when the probe is heated to a certain temperature. This electrical current tells the gas valve that the pilot is lit and its ok to send gas to the burner if the thermostat requires it.  There are some great images to illustrate how this works here.

To test a water heater thermocouple push the pilot button down on the water heater gas control valve. Then light the pilot. If after holding the pilot button down 30 to 60 seconds the pilot light doesn’t stay on when you release the button, the thermocouple is most likely at fault on older devices. The TOC or air flow might be the issue on more recent systems with a pilot light viewing window.

If the pilot does not light at all the problem is gas flow, gas control valve, TOC tripped.

Common Thermocouple Problems

The most typical issue is the suggestion on the thermocouple probe weakens. It can easily be replaced.

Thermocouple Repair

If the probe appears white in color this is carbon build up. It can keep the probe from getting hot enough to send out a signal to the gas valve. Try sanding it with emery fabric and relight the pilot. It must work for a while however keep a brand-new thermocouple helpful.

  • The thermocouple probe must be in the pilot light flame.
  • The thermocouple has to be screwed into the gas valve snugly.
  • Inspect the pilot thermocouple tube for kinks.

Water Heater Repair Oklahoma City hopes this has actually been an excellent intro to a water heater’s thermocouple for you!