Water is coming out of this valve. So I have to stop the water supply to the tank. What can I do?

no water coming to heater, valve closed, lines kinked, tank full of sediment. if new did you open hot side faucets in home to bleed air from system? bled air 5 minute afterlast air bubble leaves faucet.

a couple of things to check on the side of the hot water system you will see a valve with a small lever
lift that lever until there is a solid stream of water coming from the pipe
that ensures that the heater tank is full
next -if you have a temperature mixer on the hot water pipe out of the tank ( stops scolds in the bath, shower sink) by controlling the temperature mix at the tank
They are known to fail and shut down the hot water supply by adding extra cold water into the system
other than that get a plumber in to fix the fault.

Is there water in the hot water tank?.... As in... Is it a new tank?... Tank was filled?... Water come out the drain spigot at the bottom of the two? And the supply v valve... (Bringing for water into two).. Is turned on?
Are the any valves shut off leading away from the tank that never were opened?
Or is it an offer tank that just suddenly stopped
Please tell us more so we can help.

MB

Assuming this is not a steam boiler, your boiler probably has one or more of the following problems; (1) bad vent(s) not stopping after it purges air, (2) bad vent(s) that are blocked and can not purge air, (3) air bound caused by not inspecting #2 (and replenishing water, if needed) on a regular basis, (4) a water leak (low water cut off will prevent boiler from firing up), or (5) a defective supply water valve, or defective supply side check valve, or blocked water line, especially when sediment can easily foul the supply line. We need to look at the expansion tank. Is it water logged from a defective bladder? Is the Air Separator (near the X tank) operating properly? Similar to a vent, but larger, it can get clogged up and cause air to be trapped. Since the boiler will not start, you obviously have a low water condition. Solve that problem and you'll be warm again.

You can try to crack it open and get a little piece of crud out of there, I'm sure that is all it is, Just get a tray or something to catch the water, It should stop it, If it gets worse, turn the water off to the heater, then open the valve and hope the bigger piece of crud comes out. It is about all you can do, other than drain the whole thing and take the valve apart and replace the rubber in it. Check it out, Hope this helps.

There are two solutions:

1) Replace TP valve with same temperature/pressure as existing TP valve.
Buy the TP valve at hardware store or home center or plumbing supply.
Turn off water heater so water cools.
Hot water inside a tank is explosive ... so open the TP valve and test water temperature.
If TP is on top of tank, you don't need to drain much water before unscrewing
If TP is on side of tank, use the TP valve to drain water -or- use the drain valve
Unscrew TP to remove.
Put teflon tape on new valve threads so it will seal against leak.

2) If the new TP replacement starts doing the same thing, there may be a thermostat problem -or- thermostat is set too high.
If you keep the water temperature set high, you can add expansion tank to incoming cold water line.
Home Depot sells expansion tanks. Plumbing supply carries them,
The tank for residential water heaters is about same diameter as a football and it goes on cold water line.

Expansion tank is supposed to stop over-expansion due to pressure.
The check valve will stop over-expansion from pushing pressure back into the supply line.
The real question is what is causing the pressure.
If your TP valve is bad that could cause problem.
If the thermostat is set very high, and there is frequent short-term use of hot water, that can cause heat to build up inside tank.
Solution:
Lift TP valve and let out pressure to see if there is something lodged in the valve.
Be careful of the scalding water.
Let the TP lever down slowly.
Next step would be replace TP valve.
Turn down thermostat to 120, or set to 130-5 if objective is to kill most bacteria.
Last. You might check that your expansion tank is correct for water heater.

Hi .. if the thermostat is tripping and the safety valve is dripping , that would indicate that the water is being over heated , or the tank is at a low level . Check the thermostst setting, it should be about mid scale. Check the supply valve to be sure that there is a constant supply of cold water. Any thoughts?

Begin by turning off the gas at the tank and at the valve near the tank. CAUTION: Do not proceed any further if you do not know how to relight the gas pilot!
2) Turn off the COLD water supply to the tank.
3) Attach a garden hose to the drain valve at the bottom of the tank. Run the hose to a convenient drain location. Be careful if you use a real cheapy garden hose... some of these become very soft when hot water runs through them, and may leak! If you don't have a drain in the basement floor or suitable sump hole, you have my sympathies... this drain-down can take a while with a bucket! Oh... and be careful if you use a soft plastic bucket. It can also soften from the heated water so don't overfill it or burn yourself!
4) Open up the hot water side of any faucet. Open up the drain valve on the tank and allow it to empty. Miller time. That is, unless you don't have a sump...
NOTE: If the drain valve clogs, turn on the cold water supply to the tank to use water pressure to "blast" through the clog.
5) When the tank is empty, shut off the drain valve and turn on the cold water. This will loosen up more sediment in the tank through the churning action of the cold water in the tank. Let the tank fill partially and drain it again. In fact, if you find that the sediment starts to clog the drain valve, turn on the cold water supply to the tank, which will help loosen the sediment and blast it out.
If you have extreme amounts of sediment, you may have to repeat this procedure a few more times. Look at the drain water... if it is running clear, you are done. Shut off the drain valve, open the cold water supply and allow the tank to fill. Once water comes out of the hot water faucet, the tank is full and your task is done! Now, you can turn the electricity or gas back on to heat the water.
How frequently to clean the sediment from your tank...
This depends on the source and purity of your water supply. Some pros recommend doing it annually, some every few years. I would recommend doing a partial drain down annually if you find any sediment in the tank, otherwise every couple of years.
Remember that with an electric water heater, you must turn the power off! Even a partial drain down may expose the upper heating element to the air and permanently damage it!

Assuming you are talking about the temperatur/pressure relief valve, it is stuck open.

1. Turn off gas or electric to water heater
2. Close water supply to water heater
3. open hot water faucet on nearest fixture to depressurize hot water system.
4. close tpr valve (you may have to push in on the center spine. It may be resistant to closing from sediment. If so, opening and closing several times may solve that issue.

Once you get the tpr valve closed, close the faucet and open the supply valve. If the tpr stays closed, go ahead and turn on the gas/electric and re-light pilot and turn on control etc.

If the TPR blows again, you will need to replace it. YOu can buy a new one at any plumbing supply store. Shut down the heater again, drain a bit of water out using the valve on the bottom of the tank. there is probably copper pipe connected to the TPR valve which you may have to cut or maybe can just unscrew. The TPR threads out of the tank, install the new valve (make sure to use pipe dope or teflon tape.