RE: Ferrolli Combi Boiler Question

[Alaska1977]

Hi,

Been trying to get to the bottom of gradual pressure loss on my Ferrolli combi boiler - I'm sure it isn't to do with the PRV, I had this replaced recently and have been checking the outfall regularly when the boiler been on for a while and its dry.

My plumber says there must be aleak somewhere on the system. I can't get under our wood floors on the downstairs and not noticed anything obvious on ceilings. I'm not entirely convinced it'll be an underfloor leak as boiler was running fine at correct pressure prior to annual service. After annual service needed new PRV and problem never gone away. Have checked the radiators and all seem fine.

The only thing I noticed and excuse the lack of correct terminology was on top and around the air release valve ??? - small black nozzle towards bottom of the boiler - where there was a small amount of water but when I say small just slightly wet to the touch. Occasionally boiler sounds like its working really hard (more so than usual) and i wonder if this and the water has something to do with it. Also thought there may be a link from this to the expansion vessel ??

Any pointers as a last resort before I call my plumber in again ?

Many Thanks

 

[solheat]

you dont mention what model however did the plumber check the expansion vessel this is the first check that should be done

 

[Alaska1977]

Hi - thanks for replying. Since I posted I ran a test.

Before I left for work this morning boiler had been off for the night and pressure when I got up was just less than 0.5 bar. I thought that it would be useful to start from scratch so I checked expansion vessel pressure and pumped this to 1 bar before I pulled pump off (no water in pressure vessel noticed). I then went round the house and turned all TRV to max (as a lot of these had been off in rooms not used). I bled radiators. Then topped up water in system to 1.4 bar.

One room has underfloor heating controlled wirelessly to boiler (which has overall control of central heating) so set this to be on 17 deg C - so heating fluctuating on and off most of the day as it was a pretty cold day.

Having turned system on, before I left for the day I sat and watched the temp and pressure guage gradually rise to 80 deg C and just under 2 bar respectively. Came back quite late - about 16 hrs later and boiler on and pressure still just under 2 bar. Turned heating off, left it for about 30 minutes and noted temp dropped to about 35 deg. C and pressure dropped to 1.4 bar - so pretty much where I left it in the am.

So based on this it seems to be ok, but interested if anything I've mentioned suggests that something originally was wrong - for example could pressure have been lost because the majority of my rads were off (4 out of 7) ?

Any pointers very much appreciated.

Thanks

Phil