How to Change The Thermocouple for Your Rheem Water Heater or Slant Fin Boiler

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By rainal
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This article gives instructions for replacing a thermocouple tube for a hot water heating appliance.

Difficulty: Moderately Easy

Instructions

Things You'll Need:

Small crescent wrench, pliers, wooden matches, new thermocouple tube, ability to get down on the floor and back up

Step 1

Let me start out by saying, many of the newer appliances that are in use do not have a thermocouple. So you should check your equipment before going to the supply center to buy one. If your appliance does have a pilot then your appliance definitely has a thermocouple and it will need to be changed from time to time.
Step 2

Before you remove the existing thermocouple make sure that is the problem. Check your other gas appliances and make sure that they are working. If any of the other appliances are not working you may find that the gas supply has been shut off.
Step 3

You have made sure that there is gas to the appliance and you need to change the thermocouple to get the heat back on. Turn the knob on the gas valve to the position that says pilot. If you look close you will be able to see it written by the knob. Do not force the knob. If you find that the knob won't turn, look closely you may need to slightly push the knob in to turn the knob to the pilot position.
Step 4

Look for a thin copper tube that is attached to the gas valve and disappears into the gas burner section of the boiler or water heater. Where the tube is connected to the gas valve you will notice a small screw fitting holding the tube into the gas valve. Take the crescent wrench and unscrew it. Remove this part from the gas valve.
Step 5

Inside the burner section you will see the thermocouple attached to a bracket that holds the pilot flame so that it is aimed at the end of the thermocouple bulb. When the pilot is lit the flame heats the bulb of the thermocouple causing it to expand and hold the spring inside the gas valve. This allows the flow of gas through the valve to the burner inside the appliance.
Step 6

Remove the bulb of the thermocouple from the bracket. Some brackets have a nut that needs to be unscrewed and some are just snapped into place. Whichever type you have remove the thermocouple and take it with you to get the replacement.
Step 7

Once you have the new thermocouple reinstall it into the bracket for the pilot first. Make sure that the pilot is still aimed toward the bulb of the thermocouple. If the flame does not hit the bulb it will not allow the gas to flow and you will not have fixed the problem.
Step 8

Reconnect the other end of the thermocouple to the gas valve the same way that the original was. Tighten the nut just enough to make it firm and snug. This nut should not be over tightened you can damage the gas valve by over tightening this nut.
Step 9

When you finished installing the thermocouple it is time to light the pilot. This part requires you to be able to do several things at one time. First you have to light a match. Once the match is lit grab it with the pliers and hold it in front of the pilot. Next with your other hand press the knob on the gas valve all the way in. Holding the knob on the gas valve in will permit the flow of gas to the pilot. When the pilot is lit do not let go of the knob on the gas valve. You need to hold the knob in for approximately 10 seconds to heat up the thermocouple bulb and allow the tube to expand. If you release the knob too soon the pilot will go out and you will have to light it all over again.
Step 10

Turn the knob from pilot to the on position. The flow of gas should be released and the burner will ignite.

Comments

oneilinsd said

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on 6/18/2009 How often should I need to replace a thermocouple?

With my Rheem, I am on my 4th thermocouple in 4.5 years, I would think this is to often.

How much of the thermocouple should be in the pilot? Am I just burning it out?