The AB-40 features a brass body and a �combo connection� which allows either a threaded or sweat copper connection with the same union tail piece. The AB-40 also includes a check valve and provides an inbuilt bypass for rapid filling, high pressure testing and system purging. The A-41 provides increased capacity for larger boilers. It has threaded female connections and an iron body with a stainless steel seat. Both the AB-40 and A-41 have a heat resistant diaphragm and seat disc, and an inbuilt strainer screen. The reduced pressure setting is 14 psi. The maximum inlet working pressure is 200 psi.
Note: For backflow prevention of boiler water into the potable water supply line, install a BFP valve.
Larger hot water space heating boilers that require faster filling.