Thermal Expansion Valve Water Heater

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.

Thermal expansion valve water heater.

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. 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. As plumbers know the expansion tank equalizes pressure throughout the plumbing system by providing a space for hot water to flow into. Prevents constant high pressure fluctuations caused by thermal expansion in closed loop systems.

Thermal expansion protection can be done 3 different ways. When water is heated it expands this is called thermal expansion. Both products absorb the excess pressure in the plumbing system created by thermal expansion. Using a thermal expansion relief valve.

Thermal expansion protection is required on new water heater tanks. Installing a thermal expansion tank properly sized for the tank. The thermal expansion relief valve can replace a water heater expansion tank because it functions similarly. 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.

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. A dripping temperature and pressure relief t p valve on the water heater is an indicator of a potential thermal expansion problem. This is because when water is heated its density decreases and its volume expands see below. 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.

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. 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. Using a governor 80 ballcock.