Leak On Combi Boiler

JakiT

A long story that's been ongoing since new year.

In a nutshell, our boiler was checked, expansion vessel replaced and said to all be in working order. But pressure continued to drop after heating been on and needed topping up every day after heating only been on half hour.

Floor in boiler room damp and so next step was to investigate a leak. Got local plumber to try and detect leak with thermal camera. The camera showed a possible leak in boiler room and then going back into property but hard to be certain until start excavating. Loss adjuster from insurance company due to come next week.

However, since latest plumber been (he had a brief look in boiler and said sometimes faulty expansion vessels can cause pvr's to go but when he looked inside boiler at pvr nothing wrong with it ) a leak has developed in our boiler so now can't have heating or hot water. If the plumber had disturbed anything drastically I would have thought we'd have got a leak that day but the leak came a couple of days later.

So...what could be leaking in our boiler that has never shown before? And could this leak be the cause of our water pressure dropping where previously no engineer has discovered it?

Thanks in advance

macman

Would help if you stated the make and model of your combi.
Where is it now leaking? If the PRV has lifted due to earlier overpressure then they often will not reseat properly and need replacing.
A plumber is not qualified to work on gas appliances. Sounds like your plumber is just guessing rather than doing proper fault finding, so suggest you get a proper GSR RGI to sort it out. It should be fairly obvious if the leak is within the boiler casing itself, rather than from the PRV overflow pipe or on the CH circuit.

JakiT

Hi, it's a Glow Worm cxi, can't remember the exact model without looking it up.
It's leaking underneath, seems to be coming from a plastic fitting at the bottom but without opening it hard to say whether the leak stems from somewhere further up.
There was no water coming from PRV pipe outside but he did look inside to check something to do with the PRV if that makes any sense but it was bone dry when he looked at it.