Posted by jtown on May 13, 2001 at 05:55:50:
In Reply to: Re: pressure build up posted by cory n on May 11, 2001 at 17:59:04:
The PRV is in the line feeding water from your 'city' water to the heating system. It might look like a little flying saucer. It reduces your domestic water pressure to the heating pressure and adds water to replace leakage(Combination valves have a pressure safety with it). It is leaking through, allowing higher pressures if it is happening when off. The expansion tank allows the water to get bigger (expand) when it gets hot without dumping it on the floor each time.