This kind of tank guarantees a comfortable freshwater system on board a boat. It protects the water system from knocks, which could damage its hoses, and assures a constant water supply.
An expansion tank is required to maintain circulated water loop design pressure over a wide range of water temperatures. Tank is preset at 12 psi, and has an air valve to adjust pressure as needed. Tank may be installed horizontally or vertically. It should be piped into the suction side of the circulation pump, typically at the same location as the fill assembly.