How to Replace a T & P Valve On Your Gas Water Heater

Why would you want to replace your T & P valve and what is a T & P valve?
First a T & P valve stands for Temperature & Pressure. The valve performs a dual function. It protects against temperature build up in the tank and a pressure build up in the tank of the water heater.
You would want to replace the T & P valve if you have water coming out of the pipe and it is draining either on the floor or in a floor drain. Or you hear noises coming from the water heater tank that sounds like it is spitting water out or banging.

Difficulty: Moderate

Instructions

Things You'll Need:

• New T & P valve
• Teflon tape
• 3/4 inch union
• Small copper cutter
• (pony, midget)
• Solder torch & accessories

1. 
    
   Gas valve feeding water heater

   As with all steps, make sure you have all safety equipment like gloves safety glasses etc. Your city or state may require you to pull a permit. Check with your city & state plumbing code enforcement.
   First turn the gas valve off to the water heater. (see picture) Also turn the gas control knob to the off position.

2. 
    
   Brass water valve on the right. Turn this valve off

   Second step: Turn the water feeding the water heater valve. The valve in newer homes have a valve at the top of the tank. (see picture).
   If you have an older home turn the water off in the crawl space, basement, or outside in a pit that the water department supplies.

3. 
    
   T&P) valve on side of tank

   Step 3: Depending on your water heater you could have a T&P valve on top of the tank or like the picture shows on the side of the tank.
   You will need to take this valve out to replace, but first drain the water out of the water heater. If you have a drain nearby you can run a garden hose to the drain from the bottom side of your water heater there is a drain valve. I will show the drain valve in the step four.
   Open up some faucets to help get the air out and to help drain the water heater faster. If you break the drain valve or strip the valve because it is to old, you will have some work cut out for you. I will have another article on the procedures for that.

4. 
    
   Drain valve to drain water heater

   Step 4 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 on it. It also could be galvanized. You will have to cut the pipe about six inches from the top on the down side, because you will have to unscrew the T&P valve and you will not be able to do that with the pipe in the way.

5. 
    
   3/4 inch union or larger

   Step five: Make sure you get the right T&P valve for your water heater by taking it with you to the hardware store.
   Replace the T&P valve and put Teflon tape on the threads only, screw it in, on your last bit of tightening make sure the female threads face the way you want them to. You made your cut six inches down, now cut off about 5/8 of an inch more for the difference of the union your going to put in, but only on one side of the pipe. Do not change the direction keep everything the same. The hardware sells unions. You may have to solder all this back together. If your city or state allows you to install a compression coupling that is the simplest method for homeowners to make. Remember to not decrease the size of pipe and insure you maintain a air gap of nor more than six inches from the pipe drain to your floor drain.

6. Step 6: Leave one faucet off to get the air out and turn the water back on. Check for leaks, if none, make sure all the air is out of the faucets hot and cold. Turn the gas valve on and relight your pilot to the water heater. Having the gas valve off may require you to wait a few extra seconds to get gas to the burners etc.

Tips & Warnings

• Always be safe. Check with your local state and city to insure you can do this work with or without a permit.
• I have a new book out called "Flush Your Plumbing Troubles Down The Toilet" its available on Amazon.com. For the price of pizza for four, my new book and the information will last you a life time.
• Insure you don't flood the place and insure all the water is in the tank before you turn the gas back on to the water heater.