water spewing from hot water heater

blanche

I had no hot water, so I turned up the thermostat just a notch. Now, every few hours, water comes spewing out of my hot water heater. It continued even after I turned the thermostat back down to where it was.
If I let the hot water run out of all my faucets, the water stops spewing.
How do i fix this?

Brad White_34

Blanche

How appropriate a name in consideration of being sprayed with hot water!

(Sorry! Could not resist...)

What is the temperature of the water in the tank or, more safely, at the faucet? And what is the pressure in the system? The last question is much harder to tell and I do not suspect you have a gauge in the system. Few systems do.

The valve at the top of the tank is called a T&P relief valve which responds to both temperature and pressure hence the initials. If the water is above 210 degrees F the valve will open. If the pressure is above 150 psig it also will open.

I would rather doubt the water is that hot but it could be. You would see abundant vapor and sputtering at your kitchen sink upon sudden opening. Do check that...

Pressure is another matter. You may have a check valve at the CW inlet or other stop valve that holds the water captive within the hot water side of the system. If so you may need an expansion tank (one made for POTABLE water) to absorb thermal expansion. I suspect it is pressure because running your faucets stops the spewing and after you lowered the temperature. Check both on the off-chance that the tank thermostat is not functional and maintains higher temperatures than it says.

It could also be that the T&P valve is defective and is over-reacting to lower temperature and pressure. If so, replacement is a relatively simple matter.