You would want to replace the T & P valve if you have water coming out of the T & P valve, water is draining either on the floor or in a floor drain, you hear noises coming from the water heater tank that sounds like it is spitting water out, or a banging sound coming from the tank.
Know that you have determined that the T&P valve is bad follow the following steps to replace it.
First turn the gas valve off to the water heater. (see picture) Also turn the gas control knob to the off position.
Turn the water feeding the water heater valve. itxtvisited=”1″
Many older homes have a water valve that turns off the entire house and may be in the crawl space, basement, or outside in a pit that the water department supplies.
Depending on your water heater or any mechanical appliance you could have a T&P valve on top of the tank, inline, or like the picture shows on the side of the tank. itxtvisited=”1″
Next drain the water out of the water heater. If you do not have a drain nearby you can run a garden hose to a toilet, floor drain or anything that can accept water.
itxtvisited=”1″ This drain valve is a newer design, you would only need to open it 1/4 of a turn with a screw driver to begin draining. Its also a good idea to open a few faucets at this time to help get air out of the lines.
The water is drained and your ready to take the T&P valve out. In most cases the piping is soldered and has 90 degree elbow’s on it. If you have copper pipe and not galvanized connected to your T&P valve you will have to cut the pipe just long enough so you can unscrew the T&P valve. In this picture the piping was cut about ten inches and after the T&P valve was installed I put in a union to make it easier in the future to remove or replace the T&P valve.
Make sure you get the right T&P valve for your water heater by taking it with you to the hardware store. itxtvisited=”1″
Replace the T&P valve with a new one and as you are screwing the valve in, once it appears to be getting tight, hand tighten your short piece of pipe into the T&P valve and put your level on the pipe to insure it is plumb. Install a new coupling or union insure to never decrease the size of the piping from the T&P valve to the floor drain.
Repeat your steps to get your water heater back on line. Turn off the drain valve, slowly turn the water back on, close most faucets but keep the faucet near you open until all the air is out. While water is filling check to insure you have no water leaks on your new T&P valve and once the water heater is full of water go through the house and let the air out off all faucets before you turn on the gas light the gas pilot. Adjust your gas controller to a comfortable level once the water heater heats up. I recommend after 24 hours you test your hot water temperature with a thermometer (see picture) and adjust your temperature to 110 degrees fahrenheit