Pressure Relief Valve Discharging Outside
A copper pipe on the outside wall keeps dripping, sometimes only when the heating has been on..
A copper pipe on the outside wall keeps dripping, sometimes only when the heating has been on.
What is actually going on
A copper pipe on the outside wall keeps dripping, sometimes only when the heating has been on.
The realistic causes, in order
System pressure exceeding the valve's 3 bar setting because the expansion vessel has failed Debris on the valve seat holding it slightly open, so it passes even at normal pressure A valve that has been lifted so many times it no longer reseats
What we test on site
Pressure behaviour through a full heating cycle, logged rather than glanced at Vessel pre-charge and diaphragm integrity Valve seat condition once the pressure fault is corrected
Questions we get asked
What causes a discharging pressure relief valve on a gas boiler?
System pressure exceeding the valve's 3 bar setting because the expansion vessel has failed
What normally puts a discharging pressure relief valve right?
Almost always a vessel fault plus a valve replacement — a straightforward repair once both are done together.
Is it safe to keep using the system with a discharging pressure relief valve?
That discharge pipe must terminate safely where scalding water can't reach anyone. If yours discharges over a path or doorway, tell the engineer.