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How to replace your own hot water heater relief valve.

Ok so you want to replace your water heater relief valve.
First things first, this can be very dangerous and I strongly recommend that you have it done by a professional.
Did you read the four reasons a relief valve leaks?

First turn the power off if electric or the gas off if gas.
Then turn off the water, it may be best to turn the main water valve off, many times the valves by the water heater don't hold and sometimes water feeds back through faucets in the home.

Drain some of the water out of the water heater, just below the relief valve. If you use the drain at the bottom of the water heater you may find that it will continue to leak after you try to turn it back off.
(another reason to have it done by a pro.)

With the power or gas off and the water off and drained below the relief valve, remove the drain pipe from the relief valve, if it does not have a drain pipe on it be sure to install one on the new relief valve. it needs to be the same size as the outlet of the relief valve and co to about 6 inches from the floor, without any possible way of installing any kind of plug or cap on it.

Once you have removed the drain pipe from the outlet of the relief valve, check to be sure the water level is below the relief valve and that no water pressure has built up in the water heater.

Water Heater Relief valve Before you remove the drain pipe and the relief valve, you should prepare the new one for installation, By applying pipe dope or Teflon tape to the male threads on the bottom of the relief valve.
Note: not all relief valves are the same, aside from different styles like a longer body for side mount water heaters with thick insulation. higher BTU water heaters require a higher rated relief valve. Water heater relief valves are called T&P valves (temperature and Pressure relief valves).
Blow Off valve Check the required rating for your relief valve by checking the plate on the water heater, you can not always go with what is installed on the water heater because the person that replaced the relief valve before you may not have installed the correct relief valve.
In the image the water heater relief valve has a copper drain pipe with an elbow pointing it down, I unsoldered the 90 from the pipe so that I can remove the drain pipe from the relief valve. If you can not solder cut the pipe leaving enough room to install a compression coupling to replace the pipe.
Relief valve Now that you have removed the drain pipe, again be sure the pressure did not build up by draining off a little more water, then put a wrench on the relief valve and turn it counterclockwise till it unscrews all the way. Now I am not using the correct tool to remove the relief valve and I have the wrench on the wrong place according to the instructions on the relief valve. But I am careful not to damage the new relief valve when I install it and don't have the room to use the correct wrench on the flat spot provided by the manufacturer.

If you can not get the old relief valve to turn, Stop and call a pro 1-888-330-6270.
Note how dirty this old relief valve is, that sediment on the sensor may also be on the seat of the relief valve, if so it could cause the relief valve not to blow when needed making it useless and very dangerous.
Before you install the new relief valve be sure to clean the threads on the water heater of all sediment and debris. Go three to four times around the threads with the Teflon tape but keep the first few threads free so the relief valve catches easy.
Be very careful not to damage the new relief valve when you tighten it up be extra careful not to bent the outlet of the relief valve. remember you must reinstall the drain pipe even if the relief valve is side mounted and already pointing down.
Ok now that you have replaced the relief valve and reinstalled the drain line or installed a new drain like it is time to turn the water back on and refill the water heater. Do not put the power or gas back on yet. doing so may cause problems.
You need to get the tank 100 percent full before you turn the power on or you may burn the top element on the water heater out.
I have seen this happen so many times. You turn the water on you hear the water stop running into the water heater and you assume it is full, but it is not, air gets trapped in the top of the tank. you need to run a faucet on the hot side until you hear all of the air come out and you get a steady flow of water before you turn the electric or gas back on.
When you are done check for leaks, after the water heater has finished heating check for leaks again, then the next day check for leaks once more.
Note the date you installed your new relief valve.
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