Product details:

Thermal Expansion Tanks are designed for pressure control in potable water systems. The tank uses compressed air to maintain system pressures by accepting and expelling the changing volume of water as it heats and cools. It prevents the water heater pressure relief valve from opening, saves energy and eliminates a potential safety hazard. It is commonly installed in a domestic hot water system that contains a backflow preventer, a check valve or a pressure reducing valve. Measures 11 in. L x 7.9 in. W x 11 in. H with 2.1 Gal. tank size, 6 lbs. weight and 3/4 in. connection size (NPT).