ST-12 Amtrol THERM-X-TROL ST-12 Expansion Tank
 
Amtrol ST-12 (Therm-X-Trol) is a water heater expansion tank, designed for use in domestic hot water heating systems to eliminate the potential hazards of water expansion. Water heater expansion tank is commonly installed in a domestic hot water system that contains a backflow preventer, a check valve or a pressure reducing valve.
- Eliminates the waste of energy and water, thus saving money
 - Protects the water heater and plumbing fixtures from premature failure
 - Reduces potential safety hazards associated with thermal expansion
 - Prevents a dangerous pressure build-up in the system
 - Prevents the relief valve from going off