Thermal Expansion Valve Water Heater

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.

Thermal expansion valve water heater.

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. Thermal expansion protection can be done 3 different ways. Thermal expansion protection is required on new water heater tanks. A dripping temperature and pressure relief t p valve on the water heater is an indicator of a potential thermal expansion problem.

When water is heated it expands this is called thermal expansion. The problem is more likely to occur on water heaters that do not have an expansion tank installed in the home s water system but do have a check valve on the cold water supply line. Using a governor 80 ballcock. As plumbers know the expansion tank equalizes pressure throughout the plumbing system by providing a space for hot water to flow into.

When the pressure supplied to your home is at a suitable level between 40 and 80 ps and has a prv or check valve the thermal expansion tank enters. Prevents constant high pressure fluctuations caused by thermal expansion in closed loop systems. A thermal expansion valve is then in essence a safety device that will open and spill water and pressure to prevent plumbing equipment or piping damage or worse unsafe conditions. This is because when water is heated its density decreases and its volume expands see below.

Installing a thermal expansion tank properly sized for the tank. This check valve is designed to keep water expansion from pushed back into the city water system but unless there is an expansion tank in the system the pressure has nowhere to go except to put stress on the water heater tank itself and surrounding pipes. Using a thermal expansion relief valve. 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.

The thermal expansion relief valve can replace a water heater expansion tank because it functions similarly. They are used to prevent plumbing system and or water heater damage as well as unnecessary relief valve discharge caused by excessive pressure from thermal expansion. In hot water supply systems thermal expansion of heated water may occur wherever potable water is heated in a closed system when the potable water is iso lated from the public water supply by a one way valve such as a pressure reducing valve backflow preventer or check valve.