I have a Britony Combi 80 - made by Chaffoteaux at Maury.

Well I noticed the water pressure was slowly going down, so I refilled as normal - via a metal hose under the unit.
Then I decided to bleed the rads (upstairs had more air than water in them air!), then I obviously saw the water pressure drop rapidly and refilled until it behaved as normal...

Since then (a week ago now) I have seen the pressure drop to zero, within 2 days.
The is no *obvious* leak, there have been no changes, except I have bled the rads.

Am I missing something here?

We have had to to have the mechanical peice (I know not the name) that switches between service to the rads OR the hot water replaced *every* year for the last 4 years!
Yes the system is only 4 years old!

Thanks,
HotShot

Check a couple of things

1/Look outside at the pressure relief valve outlet. Is it dripping?

2/What happens to the pressure when the system is hot? Does it go up above 2.5 bar?

post result and we'll talk through what to do next.

Thanks Paul,

1. The pressure relief valve (identified using the manual) is fine (the combi is located in the corner of the kitchen). So drips, drops or anything else.

2. When we moved-in the pressure always dropped down to 1.0 bar, whatever you filled it up to. Now the pressure drops half a bar every day. If the boiler is off, there is no change in the pressure. When it is on low the pressure drops half a bar every day, the hotter the radiators, the faster the drop in pressure.

I know this shouldn't have anything to do with it, but...the LCD display has failed, I can just make out it trying to show the time...

Cheers,
HotShot

The pipe from the pressure relief valve goes through the wall to outside usually, it may alternatively have been run to the kitchen waste in your case. Anyway you are to find the end of it and obsevre for water coming out of it no matter how small an amount.

Because you say it looses pressure when it has been on, I suspect that it may be your expansion vessel. These are charged with air to something between 0.5 and 1 bar, quite typically they are 0.7 bar. If this is the cause of your problem either the air has escaped or the bladder is burst. There is a Schareder valve on it, depress the needle briefly, if water comes out you need a new expanshion vessel, if not, get a bike pump, let all the air out, Read the pressure guage, pump up the vessel with the bike pump until the pressure guage shows an additional 0.7 bar.

I eventually got away from my PC...

The pressure relief valve outlet pipe is dripping, alot.

I have called an engineer out - If it's something simple I can do it, but I doubt it.

Any ideas on the potential fault?

I don't want to get ripped-off by the engineer, unless the fault can be *easily* fixed by me.

Thanks for your help,
HotShot

If it only does it when the boiler is running you have expansion vessel problems which I've detailed above. If you were competent to fix it yourself you'd have understoof that, so good idea to get the professional in.

Paul