All water heaters, including tankless water heaters, should have a temperature / pressure valve, or T/P valve, installed somewhere on the tank.
Water heaters are essentially pressure vessels that are capable of withstanding large amounts of pressure and heat. It is up to the T/P valve to open and release these pressures. However, when the T/P valves do not open, catastrophic failure can occur. I recently ran across a video regarding water heaters and what happens when they explode:
Now, this doesn’t happen very often and is very, very rare. However, it can happen and the best way to avoid is to do the following:
- Check the valve on a semi-annual basis. When tested, you should hear water coming through the valve and down the pipe. If you don’t hear this, then you should contact a plumber.
- Sometimes the valve does not fully close and keeps running. If you can’t get the water to stop, then we recommend contacting a plumber for repair.
- The valve should be free of corrosion and / or rust. We recommend keeping this valve clean and, if corrosion is found at the connection and appears to be major, we recommend contacting a qualified plumber.