A commercial building connects to a boiler that uses chemical additives and is served from the potable main. What premise-isolation protection does the code generally require at the service?

Giải thích

A boiler treated with chemicals is a high (health) hazard with potential backpressure, so premise isolation generally requires a reduced pressure principle assembly (RP). A single check valve and a pressure regulator provide no adequate high-hazard protection, and boilers are not exempt from cross-connection control.