Description A.Y. McDonald Hydronic Expansion Tank - 2-5 Gal Baker Water Systems Hydronic Expansion Tank. Designed for the specific purpose of accommodating the natural expansion of water in a hydronic heating system. Air and water are permanently separated by a butyl diaphragm to eliminate water logging. Light in weight, easy to install, and affords many years of trouble-free service. Not for use with potable water heating systems. Technical Details Drawn Steel Construction Butyl Diaphragm In-line Installation Maximum Working Pressure 150 PSI Maximum Temperature 194°F 18 PSI Air Charge (field adjustable) 2-Year Limited Warranty Not for use with Potable Water Heating Systems 1/2" MNPT connection How It Works Start-Up Cycle With water chamber empty, diaphragm is pressed against bottom of chamber. Fill Cycle As water is pumped into water chamber, diaphragm is forced upward into air chamber. Hold Cycle When pressure in air chamber reaches pump cut-off point, diaphragm is in uppermost position, water chamber is filled to rated capacity. Delivery Cycle When water is delivered to system, pump remains shut off. Air pressure in top chamber forces diaphragm downward. Datasheets Pressure Tanks Guide
