How Thermocouples Work on Ones Miami Water Heater

Posted by on Dec 9, 2013 in Water Heater Repair Miami

Ok, not to get too technical with you today, but Water Heater Repair Miami 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.”

Standard design
Likewise 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 can be found in lengths from 15 to 36 inches. An 18 or 24 inch will suffice for all residential water heaters making use of universal kits. Virtually all older waters heaters and numerous of the more recent design units with a closed burner compartment and a seeing window will utilize this thermocouple.
If you want to use an exact replacement length simply eliminate your old one and measure it.

TCO design

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

TOC non-resettable style

These thermocouples have a small TOC build inside the tube. They look much like a basic one other than the diameter is bigger about midways of television. When these TOC’s turn off they will not reset and have 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 specific temperature. This electrical current informs the gas valve that the pilot is lit and its ok to send out gas to the burner if the thermostat calls for 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 let go of the button, the thermocouple is most likely at fault on older systems. The TOC or air flow could be the problem on newer devices with a pilot light viewing window.

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

Usual Thermocouple Problems

The most common issue is the idea on the thermocouple probe degrades. It can easily be replaced.

Thermocouple Repair

If the probe looks white this is carbon build up. It could keep the probe from getting hot enough to send out a signal to the gas valve. Try sanding it with emery cloth and relight the pilot. It needs to work for a while however keep a brand-new thermocouple handy.

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

Water Heater Repair Miami hopes this has actually been a great introduction to a water heater’s thermocouple for you!