Combi boiler pressure loss

[Jborgy]

Have an ideal logic 35 boiler, logic.
Was loosing pressure several times per day on water and heating but just had new vessel and PRV fitted, now water fine, but on heating would be ok while heating on, rads hot and pressure ok, when heating stops and fan runs for 5mins then boiler stops the pressure starts to drop, and 2 mins later no pressure have to fill loop.
Rads been vented, no leaks can see or feel.

 

[jj4091]

Diverter valve leaking? Was it serviced before the expansion vessel was changed. Is there any signs of water dripping from the bottom of the boiler. Has the new expansion vessel been pressurised?

 

[Jborgy]

Hi, not serviced for a while, had replacement pressure vessel and PRV which has made a difference, before lost pressure on water or heating serveral times a day. Now with water on pre warm dont loose pressure constantly but yesterday wife said water was cold and found water released from PRV.
The boiler set at 1bar, and vessel about 0.8bar.
Put heating on 3 time in the day pressure stayed OK.
For some reaso must over pressure past 3bar.
Few days ago did see the heating finish the. Heating stop but fan stays on for about 5 mins and pressure ok, when fan stopped see pressure drop slightly but then started to drop quick felt PRV 15mm copper pipe to outside was warm.

Just seems to be a intermittent fault .
No leaks on boiler, checked rads, vented them.

 

[jj4091]

I'm not a heating engineer but I think the expansion vessel should have more than 0.8 bar in it. I'll report your post and ask for it to be put in the plumbing and heating section where you may get more advice but I suspect it may be that you need to get the other guy or another gass safe heatin engineer back to it.

 

[Jborgy]

Hi
Some say 1bar and same for boiler, but the label shows 0.75bar and seems to be better as was at 1bar.