Ask The Trades - Print Page

Ask The Trades
https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Plumbing Questions >> Combi Boiler Losing Pressure https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1299856380 Message started by RoyD on Mar 11^th, 2011, 3:13pm

Title: Combi Boiler Losing Pressure
Post by RoyD on Mar 11^th, 2011, 3:13pm

Good Afternoon All

I am new to this forum and a DIY novice so go easy on me please!

The problem I have is as follows. I have a Ferroli Optima 1001 combi boiler which is losing pressure. I have checked the radiator valves and bleed valves and cannot find a leak anywhere.

The pressure is dropping regularly and generally whenever I want to use the heating I need to re-pressurise the system. Once the heating is on there does not appear to be any pressure loss. Also if there is a little pressure (say less than 1bar) and the heating is switched on the pressure seems to re-adjust up to 1-2 bar.

I'm now thinking there may be a leak under the floor which would be a problem for obvious reasons. Are there any other avenues I should explore?

Thanks for your time and any opinions are most welcome.

Title: Re: Combi Boiler Losing Pressure
Post by thescruff on Mar 11^th, 2011, 4:27pm

Obvious things first.

Is the pipe sticking out the wall passing water, tie a plastic bag over the end.

What does the pressure rise to, if you set the boiler at 1.5 when cold and turn it on.

Have you checked all the rad valves and fittings for weeps when the rads are cold.

Title: Re: Combi Boiler Losing Pressure
Post by RoyD on Mar 11^th, 2011, 4:50pm

The pipe coming out the exterior wall is passing water.

I have checked all the radiators when cold and none of the valves are wet.

The pressure rises to about 2.5 bar or so when put to 1.5 bar when cold.

Title: Re: Combi Boiler Losing Pressure
Post by Wayne B on Mar 11^th, 2011, 5:08pm

Is it the copper pipe to outside passing water bud?
Not the condensate/plastic pipe if your boiler is a condenser.

Title: Re: Combi Boiler Losing Pressure
Post by CWatters on Mar 11^th, 2011, 10:24pm

I don't think it's a condensing boiler....

http://www.ferroli.co.uk/product_documentation/DOMESTIC_ARCHIVE/Optima_1001_Manual.pdf

Looks like the Pressure Relief Valve and/or the expansion vessel should be checked.

The expansion vessel is basically an air filled chamber designed to accomodate the expansion of the water when the systems heats up. If it's lost it's charge or become faulty the water has nowhere to go and the pressure rises too much. If the pressure goes high enough the PRV open and you get water out the pipe. When system cools down again the pressure then falls below normal.

It's possible the expansion vessel just needs recharging (with a car tyre foot pump). The proceedure for checking this and recharging hss been posted on previous threads.

Title: Re: Combi Boiler Losing Pressure
Post by Wayne B on Mar 11^th, 2011, 10:39pm

If the pressure relief valve is passing water will escape to outside through that copper 15mm pipe bud get the valve swapped and that will be where the pressure is going :)

Title: Re: Combi Boiler Losing Pressure
Post by thescruff on Mar 12^th, 2011, 1:20am

Sounds like the expansion vessel needs it's pre-charge pressure topped up or it's duff.

Title: Re: Combi Boiler Losing Pressure
Post by CWatters on Mar 12^th, 2011, 8:08am

The good news it it probably isn't a leak.

Title: Re: Combi Boiler Losing Pressure
Post by RoyD on Mar 12^th, 2011, 10:45am

Guys thanks for all your posts. I will get the pressure relief valve and expansion vessle checked out.
I assume this is something I would need a Gas Safe registered plumber to look at? Any idea of the typical cost?

Title: Re: Combi Boiler Losing Pressure
Post by RoyD on Mar 12^th, 2011, 10:51am

Also just to let you know I out a balloon over the end of the outside pipe yesterday and this morning the ballon was bust and when completely removed from the end of the pipe a far bit if water came out.

Title: Re: Combi Boiler Losing Pressure
Post by Wayne B on Mar 12^th, 2011, 1:07pm

Like I said the pressure relief valve is nackerd bud get that changed and its a 5 min job to test the pressure vessel your engineer will do that anyway at same time. :)

Title: Re: Combi Boiler Losing Pressure
Post by CWatters on Mar 12^th, 2011, 2:19pm

Recharging an expansion vessel or replacing a PRV shouldn't be expensive. Replacing the expansion vessel will be more expensive. If the one in the boiler is hard to get at it might work out cheaper to leave it in there and just fit another one elsewhere in the system. The expansion vessel should have a car tyre valve on it. If water comes out of that when it's pressed the exp. vessel will need replacing. If only air comes out or nothing then it may just need recharging/pumping up.