Potterton HE30

This boiler is continuously loosing pressure over a period of two days.
There is no sign of water damage to the ceilings and can not hear any noises that could be associated with leaks under-floors, all tails, valves, and end caps seem to be free form leaks.
Can I assume there is a micro leak of some description under the flooring downstairs, if so is there a pressure test that could isolate/pin point the leak or is it crawling job? Is there anything else it could possibly be?

OK then, the pressure relief pipe that exits the base of the boiler should terminate externally, is there any sign of damp at its outlet point? (try hanging a rubber glove over it to catch any drips if unsure.)

If not, try turning off the isolation valves under it, to separate the boiler from the rest of the heating system. If the pressure still drops the problem is at the appliance end.

And, finally what Gas Boiler is it?

End of free advice service.

Dreadnought

dreadnoughtheating said:

OK then, the pressure relief pipe that exits the base of the boiler should terminate externally, is there any sign of damp at its outlet point? (try hanging a rubber glove over it to catch any drips if unsure.)

If not, try turning off the isolation valves under it, to separate the boiler from the rest of the heating system. If the pressure still drops the problem is at the appliance end.

And, finally what Gas Boiler is it?

End of free advice service.

Dreadnought

Click to expand...

Its a Potterton HE30 he told you.

Or rather a 30 HE

Is it the performa combi he 30 if so turn off the 2 isolator valves under the boiler and see if the pressure drops still it could be the secondary heat exchanger leaking down condense pipe.

If water is escaping out of the pressure relief pipe, what is the diagnostic? Not checked yet it's a friends.

dreadnoughtheating said:

And, finally what Gas Boiler is it?

Click to expand...

Yes it's a Potterton 30 HE or possiblly the dyslectic version HE30

dreadnoughtheating said:

End of free advice service.

Click to expand...

tight git!

Okay, this is what has been done. System filled up and pressure to 1.0 bar, flow & return valves for C/H closed. System control put to Hot water only, bag over external condensing pipe and bag over external vent/blow off pipe.
System dropped to near zero within a two days, a little water found in bag over condensing pipe, non at blow off! No external leaks could be spotted.
I am I right in thinking this could be something to do with the recuperation of heat exchanger?

Update on the above problem!
The boiler was under a service contract and a engineer was requested to look at the boiler for fault. No boiler fault was found.
On further investigation, when the central heating system was set to max temp, there was evidence of very slight weeping/moisture around nuts of some rad valves, it was then found that a number of these nuts, were slack and some could be tightened in excess of a full turn.
But no really signs of damp beneath the valves or on flooring (lino, carpet, underlay, floorboards)?
Since the nuts have been tightened the pressure is holding steadily.
So my questions are:
1) If the central heating valves are closed both F&R, why would the pressure drop in such away, if no problems with boiler components?
2) Could it really be possible for the central heating system to dump that amount of water out with very little evidence of this?

The house has eight rads on two floors all connected together in a flow/return loop, so no branch off pipes to single rads.
The system when full will hold about 15l of water, the working pressure is generally set at 1 bar at the boiler.