ariston eurocombi boiler losing pressure

[alidyer]

I got charged £100 to get the pressure release valve replaced last week because we were losing 0.2 bar pressure per day. It's still dropping 0.2 bars a day!! One corgi registered plumber said it's most likely a problem with the expansion vessel and another has said it could be a leak but might be a problem with boiler itself. I don't know what to do!!

 

[ChrisR]

Does the pressure go UP much when the system heats up from cold?
Look hard at your radiator valves tops - under the caps. Any signs of leaks?
Does the pressure drop if the boiler isn't used?

 

[alidyer]

Pressure goes up by about 0.8 bar when the heating is on. No signs of leaks from radiator tops that I can see. pressure drops much more slowly whan boiler isn't used but I think it still drops a tiny amount. The other day the PRV was dripping at a pressure of 1.5 bar and the bloke who replaced it put the pressure when the system was cold up to 2 bar so it went over 3 when the system was on and stayed there for a day and has gradually come down since. Once the pressure goes below about 1 we don't get any heating or hot water. Our radiators downstairs are frequently cold/er at the bottom than the top which improves slightly if we bleed them but happens again. I've no idea about boilers so am not sure about what's going on!
W've had the heating off overnight and pressure has dropped less than 0.05 bar. It's now 1.4 but we have no hot water now cos the boiler isn't firing when u turn the hot tap on!! The pilot light hasn't gone out either!
Just filled it so presure is 1.8 when cold and we now have heating and hot water!. But I'm sure this is too high!