This Amtrol THERM-X-TROL ST-12 has some cosmetic damage incurred during shipping. For detailed photos please click 'See Additional Images' above. This Amtrol THERM-X-TROL ST-12 includes Alpine's premium guarantee.
For product specs and photographs of product in its original condition, click here.
An expansion tank is a required component for all hot water boiler systems, and is designed to control system pressure and help reduce energy consumption of heating and circulating operations. These Amtrol expansion tanks are factory pre-charged and 100% tested to keep the diaphragm flush against the tank when the system is first filled with cold water. As the system water temperature increases, the expanded water is absorbed by the tank. As the system water temperature reaches its maximum, the diaphragm flexes against the air cushion to allow for the increased water expansion. These expansion tanks feature a Butyl/EPDM diaphragm for superior air retention, nine times better than natural rubber.
Thermal expansion occurs as domestic water is heated. Left unchecked, the resulting pressure increase can cause relief valve discharge and other potentially unsafe conditions. Therm-X-Trol® expansion tanks absorb this expanded water, keeping water pressure at a safe level.
- Easy to install - maintenance free
- Molded, polypropylene liner for maximum corrosion resistance
- NSF 61 approved
- 5 year warranty
Water heater manufacturers and plumbing codes require the installation of an expansion control device if a backflow preventor, pressure reducing valve or check valve is installed in the domestic supply line.