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.

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.

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

http://www.ferroli.co.uk/product_documentation/DOMESTIC_ARCHIVE/Optima_1001_Manu...

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.

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

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?

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.