I have a Ravenheat combi boiler and the pressure got to above 4 so I released the pressure by turning the red (3 bar) valve inside the boiler (because that's what the plumber did last week and charged me a call out fee!). I then increased the pressure by turning the small water valve until the pressure was 1.5. However, the pressure went straight back to zero when I shut the water valve off. How can I keep the pressure in the boiler or is it kaput?

B Griffin, February 2008

Hi Guys,

I have a Raven combi boiler installed in 2001 it old but has work really well apart from needing a new pump. That was until I had a new bathroom installed and the plumper messed around with it. Can get the plumper back retired so they say.

Anyway its to do with the pressure and I have check several times for leaks none. The red bar use to be 1.5 ish and the black use to be about 1.75 and there it stayed use to get some hot water downstairs after a few min but now nothing unless the heating is on it will not work indepentantly from the heating switch, yes tried anything. But the pressure just seems to be claiming and the value that show you were the add water is dropping and no hot water independ of the heating system any ideas

louise, May 2012

water goes out of the boiler through overflow pipe

shk, July 2008

you should never use pressure relief valve as a drain off. the expansion vessell may be gone or needs pumping up press the little valve on the expansion vessel if water comes out its had it if not you may be able to pump it up with a bike pump to just under a bar, prv needs replacing by the sound of it.

martin, March 2008

Sorry, meant to add, if you need to take pressure from your system, use the bleed vent on a radiator....much easier!

Tony, February 2008

Hi,

Is there water leaking from your boiler overflow outside?
If so, it is because this red 3 bar valve, is a safety valve and should not be used to drain water from a boiler, what can happen is some dirt gets trapped under the seat of the valve and then it weaps forever.

You can drain your boiler (from its drain point, see manual) and then remove the 3bar valve, take it apart and clean it.

But, you also say your boiler pressure got to 4bar! the safety valve should lift at 3bar (hence the name!)

If your boiler pressure is climbing this high all the time when in use sounds like the pressure vessel may be shot

Tony, February 2008