Thermal Expansion Valve Hot Water Heater

Expansion tanks aka thermal expansion tanks are essentially safety devices to help you minimize the risk of damage to your hot water tank they are an add on to your existing hot water heater and are often installed on the water supply pipe to the water heater normally this is on the wall next to or very close by your hot water tank.

Thermal expansion valve hot water heater.

The thermal expansion relief valve can replace a water heater expansion tank because it functions similarly. This is because when water is allowed to continuously drip from the t p relief valve minerals from the water can build up on the valve eventually blocking it. This blockage can render the t p valve useless and potentially lead to hot water heater explosions. This is the valve with the small handle or lever that automatically opens when either the temperature or pressure inside the heater tank exceed a set limit usually 150psi 210 f.

A dripping temperature and pressure relief t p valve on the water heater is an indicator of a potential thermal expansion problem. As plumbers know the expansion tank equalizes pressure throughout the plumbing system by providing a space for hot water to flow into. When water is heated it expands this is called thermal expansion. When 40 or more gallons of superheated water is suddenly brought to atmospheric pressure and instantaneously vaporizes the massive expansion can launch your water heater through your house.

Nor does the standard temperature and pressure relief valve adequately correct the water heater thermal expansion problem. A thermal expansion control valve is essentially a pressure relief valve installed at a water heater to prevent forming excessive pressures in the closed loop of water supply piping and water pressure tank when water is heated at the water heater. The tprvs themselves are not usually a problem on water heater installations as they come installed in the water heater. A temperature and pressure t p relief valve is not considered a thermal expansion device.

For example water heated from 90 f to a thermostat setting of 140 f in a 40 gallon hot water heater will expand by almost one half gallon. This is because when water is heated its density decreases and its volume expands see below.