Why does my boiler lose pressure when switched off? Over a prolonged period of time,your boiler will naturally lose some of its pressureso if this is a one-off occurrence, it is normally nothing to worry about. If you are repeatedly losing pressure, you may have a water leak somewhere in...
You didn't give the fuel for this boiler. If it's heating oil and if the boiler is over-fired (oil burner nozzle size in gph or oil pressure too high) that could also cause the boiler to "get ahead" of the building's heating piping: water in the boiler heats up very rapidly and...