How the Amtrol FILL-TROL(c) Expansion Tank System Works:
Water enters the FILL-TROL valve, pushing open the check valve, and flows into the heating system. The automatic shut-off valve is kept open by the diaphragm pressing against the pressure plate, raising the stem of the fill gate, which compresses the automatic shut-off valve spring. When the heating system reaches fill pressure, the tank's diaphragm depresses, and the automatic shut-off valve is closed.
Whenever system pressure falls below 12 psig, the automatic shut-off valve is pressed open by the diaphragm. Make-up water flows into the system to restore pressure. http://www.plumbersurplus.com/Prod/Amtrol-110-FILL-TROL-Expansion-Tank-4-4-Gallon-110-1/7938/Cat/219
The AMTROL FILL-TROL(c) system consists of a specially adapted EXTROL pre-pressurized, diaphragm-type expansion tank, and the FILL-TROL, a specially designed, automatic, fill valve.
- Provides accurate system make up
- Eliminates need for a separate, automatic fill valve
- Fully adjustable up to a maximum working pressure of 100 psig
- Factory pre-charged; tank pressure controls system fill