Boiler losing pressure hours after re-pressurising ?

[Radam87]

Hi all

I re-pressurised my boiler last night. After the heating had been on and then switched off, the pressure had dropped to almost 0 again within a couple of hours of the heating being switched off via the timer. I've had British Gas out as I have Homecare and they can't find a problem but they have suggested adding Furnox F1 and a magnetic filter. Without know much about plumbing I can't see this helping this particular problem? I understand it's probably a good preventative measure overall but it's a bit of a financial hit at £255.

I've bled all the radiators and can't feel any cold spots, though the bottoms of some of the rads tend to heat up slower than others. No leaks to my knowledge.
The engineer struggled to find a pipe outside they said "lets out pressure when the boiler over-pressurises".

I hear a running water sound in the pipes near the bedroom for about 10 mins about an hour after the heating has turned off and I am wondering what the significance of this is as I am sure it corresponds with the pressure drop. When the heating is on the pressure bar actually rises to an acceptable level and goes back into the green. Within a couple of hours it's in the red again just above 0.

I recently moved into this property and they recommended the inhibitor when I had my initial service. They assured me that the boiler is a very good Wooster despite being 15 years old.

Any ideas? Many thanks in advance.

 

[footprints]

F1 is a rust inhibitor and a filter just collects c**p floating around the system neither will help with leakage from the system, engineers are pressurised by BG to sell those extras wherever possible, just marketing which is fair enough but neither will solve your problem.
Cause is leakage from the system, can be a leaking joint anywhere, a faulty PRV (safety valve) or faulty pressure vessel causing excess pressure that is released by the PRV.
Any engineer can rule out PRV fault or expansion vessel fault quickly. That leaves a leak on the system which can be hard to locate. Call them back to sort it out.
Of course bleeding the system will also drop pressure.
Always pressurise when system is cold.

 

[Radam87]

F1 is a rust inhibitor and a filter just collects c**p floating around the system neither will help with leakage from the system, engineers are pressurised by BG to sell those extras wherever possible, just marketing which is fair enough but neither will solve your problem.
Cause is leakage from the system, can be a leaking joint anywhere, a faulty PRV (safety valve) or faulty pressure vessel causing excess pressure that is released by the PRV.
Any engineer can rule out PRV fault or expansion vessel fault quickly. That leaves a leak on the system which can be hard to locate. Call them back to sort it out.
Of course bleeding the system will also drop pressure.
Always pressurise when system is cold.

Thanks - so call them out as it's likely a leak (though I'm not sure if it's covered)?

Is the filter and inhibitor worth having?

Does the fact that the pressure goes up when the heating's on have any significance?

 

[footprints]

Yes I used to be a BG engineer many years ago, like any company there are lots of very good engineers but some I wouldn't trust to put a no answer card through the door for me.