Thermal Expansion Devices
In recent years cities and counties have been replacing water meters with units that incorporate a check valve built in. This allows water to flow in through the meter but not back out. This creates a closed system within the house piping. The problem that can then occur is that water is heated in the water heater tank, and thermal expansion increases the volume of that water. As a result, pressure rises dramatically on the piping system and on the faucets in the house. The safety valve on the water heater can be triggered from this high pressure.
The solution to this situation is to install a thermal expansion valve which discharges water periodically or to install a thermal expansion tank. Thermal expansion tanks are usually the preferred choice because they don’t discharge water and are less costly to install than other methods.
