Ariston MicroCombi 23 MFFI - Pressure Loss

[rstanway]

Hi

I've had a quick look back over the forum and not found quite the same problem as I have.

Basically the pressure keeps dropping in the central heating and therefore the boiler won't fire. If I top the boiler up to 1.5 bar it's not long before it drops again.

The boiler was in the house when I moved in 2 years ago and works fine but for this problem. It was installed in 2001.

Last night at 11pm after the CH was off I topped the system up to 1.7 bar and closed both the flow and return values to see if the loss was boiler or pipe work.
This morning at 7am the pressure on the boiler read 1.4. I then opened the flow value and the pressure dropped to 1 bar, when I opened the return there was no change.

I then add water to 1.5 bar and went to work, my wife now informs me that the pressure is now 1.3, 3 hours later.

So what should I be looking at? There seems to be pressure loss on both the boiler and pipework. I can check the rest of the pipework tonight but I couldn't see anything when I had a quick look at the weekend. I'll disconnect the pipe from the pressure release tonight and see if its coming out of there, as it currently drains outside.

The only information I can think to give you is that all the rads have been bled and when the heating comes on the pressure normally goes up to 3 or 3.5 which I thought high.

Any advice would be great!

Many thanks

Rob

 

[kevplumb]

The only information I can think to give you is that all the rads have been bled and when the heating comes on the pressure normally goes up to 3 or 3.5 which I thought high.

get the expansion vessel checked

 

[rstanway]

From reading pages in here I see that the expansion vessel should have a pressure of 1 bar and that checking and altering this is an easy job. I've just taken the boiler front and sides off and given it a clean, while I'm here can someone tell me where I add and pressure to the vessel?

Cheers

 

[waterworks]

The big round silver vessel at the rear find the dust cap like on a bike and pump up as per faq's

These boilers seem to lose pressure over a period of time not as fast as yours though, i have not found out where it goes although i have fitted lots of them in the past.