British Gas 532i losing pressure

[Kewat66]

Hi All,
i have been working on a British Gas 532i ( Worcester with BG badge )
boiler kept losing pressure. Checked the pressure in the vessel and noting showing so re-pressurised to 1 bar. Called back next day as pressure dropped to zero on gauge. So I changed the vessel & prv. Refilled system to just over 1 bar and boiler went into the venting mode. Waited for 45mins and all worked fine.
an hour later I get a call saying pressure has gone down to .5 bar but all still working. What I did notice On filling the boiler the gauge wouldn't go past 1.5 bar but you could here the water going in still.
could this be a faulty gauge showing 1.2 bar but really be over full and dumping the water?
thanks
kevin

 

[ShaunCorbs]

was it dumping water out the prv when you tested warm if no sounds like they may have a leak on the system

 

[Kewat66]

Yes customer said he can see it dumping through prv. I initially checked the system but couldn't see any leaks though the house is a bungalow and have looked under all accessible boards.
Just seems strange.

 

[macackau]

Have you checked you haven't got water leaking out of a faulty AAV somewhere?

 

[gassed up]

Could expansion vessell pipe/hose be blocked?

 

[Kewat66]

No water was seen near the aav.
I will have a look at the pipe though.
I am thinking the gauge is reading wrong so have told them not to top up and see if it holds on .5 bar and continues to work.

 

[lame plumber]

if its dumping out the prv there is an issue, and it needs resolving, swap pressure guage, clean inlet to pressure guage for starters and get it sorted, leaving it on .5 isnt doing the customer any favours really.

 

[Kewat66]

That is my thinking. It may be showing .5 but could really be 1 bar if the gauge is faulty

 

[jonnyswamp]

Changed one in feb that had a leaking main heat ex (incidentaly my own was leaking as well)
When you can verify the pressure, top it up and keep an eye on the condense trap/pipe, if theres water running(when boiler switched off) the heat ex is kuffed

 

[Kewat66]

Thanks. Ran boiler today, closed f&r valves. Turned boiler off and water was coming out of condensate and nothing from prv so your diagnosis is the same mine. Pressure dropped. Faulty heat exchanger.