Replacing shut off valves is easy whether it be liquid or gas. You must first obtain the valve you need that is a replica of the one you are replacing in regards to the size, thread, and type. The purpose of a supply valve is to isolate the item after the valve from the rest of the system. Since the valve is there to isolate a item, the entire supply will have to be temporarily shut off. In the case of water, you may need to drain some water out first so you don't have a lot come out when you remove the valve. If it is a gas valve, most everything will be the same except as noted. You should be able to see the entire valve. If this valve is at the end of a line, then there is a metal or flexible supply line connecting the faucet to the valve.
Step 1
Determine what size you need ,and remember there is a difference between compression fittings and iron pipe fittings. They are not interchangeable. If you can't shut everything off, remove the valve, and then take it with you to get the new one, you will need to make some calculated guess or measurement and get a couple of selections so you won't have to return to the plumbing or hardware store.
Step 2
Try to always use the proper tools. Supply valves under the sink typically can be removed with a crescent, open end wrench, or channel lock pliers. The bigger valves will need a pipe wrench. If you have a big valve, you will need two wrenches, one to hold the pipe and one to turn the valve. Proper tools will prevent you from damaging the fixtures, or causing an injury.
Step 3
Find the next valve up the line from the one you want to replace and shut off the supply to the bad valve. This might be the hot water heater, the house water shut off in the house, the main shut off at the meter. Gas valves typically have some other shut off in the proximity of the valve before you get to the main.
Step 4
Drain and verify the water is off. If the valve is located in a basement or first floor of a two story house, the water above you must drain out. Most systems are not air tight enough to hold back the leftover water. If you have a floor above you, go outside and open an outside faucet if those faucets come directly from the house. Now the water will run outside and not into your cabinet or floor. You could also open the sink or tub faucet. If there is a lot of water behind it, it may seem as if the water is still on. Wait a couple of minutes. If it doesn't stop, you don't have the water shut off.
Step 5
Disconnect the line from the valve that is supplying the faucet. You will get a little water running out.
Step 6
Remove the valve. With the proper wrench, remove the valve. Watch the pipe you are threading it off of and make sure the pipe doesn't twist. If it does, you need to put another wrench on the pipe.
Step 7
Apply the proper pipe joint compound to the pipe threads.
Step 8
Install the new valve. Tighten with wrench until it is snug and in the proper location for the supply line. Turn the new valve off.
Step 9
Prepare to turn water back on. Make sure the valve is off. Turn off any drains you opened. Turn water back on.
Step 10
Check for leaks at the valve. If there is a lot of air in the pipe, it may not be immediate that the water is at the valve.
Step 11
Reconnect the supply line using pipe compound if needed. Most supply lines don't require pipe compound, but you should inspect the o ring if it is a flexible line. If it is a gas flex line, a little pipe compound needs to be applied to the flare part of the fitting, just at the end of the brass fitting, above the threads.
Step 12
Open supply valve and inspect for leaks. Tighten if needed. Turn on water faucet and check one more time. If this is a gas line, apply soapy water to all fittings and look for bubbles. Tighten if needed, re-check with soapy water. Re-light pilot if a gas appliance.
Tips
- Think ahead. Don't do this if you need water right away and the store closes in an hour. If you have the wrong size or break something else, you now have all the water shut off and you won't even be able to get a drink.
- Use the proper tools. If you're replacing the supply valve because you broke the handle by using wire cutters, go get the right tools. This is one of those simple jobs that will mess a lot of things up if you try to take short cuts.
- There are several types of pipe joint compound. Make sure you have the right one for your application.
- The valves are size and thread specific. You must exchange one for one, apples for apples.
Warnings
- Gas valves are not really dangerous, but you must be careful to shut off the valve behind the one you want to replace. You can imagine what might happen if you didn't shut the valve off and then remove the one you want and go to the store to get a new valve.
- Since you can't see gas (unlike the water drips), you must check everything you loosened with soapy water.
- Make sure you have the water or gas shut off before removing the old valve. Once you take it off, there is no stopping whatever is behind it.
Things You'll Need
- Correct wrenches or pliers
- teflon tape or pipe joint compound
- replica of valve you are replacing
- if Natural Gas - use Natural Gas joint compound
