combi boiler - pressure gauge too high and overflowing

[Shafty-Bobs]

I have an Ideal c24 mini combi, approx 8 years old, that is leaking hot water from the overlow (pressure relief valve) pipe outside - I estimate approx 1 lite per minute.
The pressure on the guage was reading maximum at 3.5-4 bar so I assumed somebody must have opened the filling loop too much and let water in by accident. So, I swithched the boiler off and opened the drain cock and let water out of the rads until the pressure dropped to 1.5 bar. When I switched the boiler back on the pressure started building-up again to the max 4 bar and the leak started again. What is going on?
The heating is working fine but I am worried. Any ideas?

 

[jackecole]

have you turned off the cold inlet to the combi ? does the problem then stop?

 

[lightning]

Filling loop may be passing

Expansion vessel may need recharging see faq

 

[jackecole]

if boiler off at spur and prob persists - plate heat ex is passing - if when boiler on (ie heating on) suspect expansion vessel charge fault/diahphgram etc fault - filling loop should be removed after system topped up

if expansion vessel was at fault gauge would read 0 on own though after prv has released water

 

[Shafty-Bobs]

the filling loop was letting small amount of water even when shut so I tightened it a bit more by applying pressure on te lever and that stopped it. hopefully sorted. thanks for the advise