Air in radiators – running out of ideas !

[Poisonata]

I'm considering calling Bosch to investigate the possibility air is being pumped into the system, I see no other explaination especially with the plumbers final thoughts on the matter.

Anyone disagree or anything else I can try.

Thanks alot in advance.

Bosch won't be the slightest bit interested. Nothing wrong with their boiler.

We shall see !

 

[Mikefromlondon]

have you investigated if your pressure vessel is Ok and pressurised to take water expansion, if not then as your boiler heats up water, the extra pressure leaks out from the PRV, ( Pressure relief valve) and when it cools down it may suck in air through a faulty automatic air vent, and this air then travels to the highest pouint and traps in your two rads upstairs!

 

[Poisonata]

Thanks for your reply. I have already considered this option though as the boiler is under warranty I have yet to do any work on it myself. No observable leakage from the PRV and as the pressure has never really gone over 2.1 - 2.2 bar (on highest boiler setting) and it blows at 3 if i remember rightly I would not have expected it to. The pressure on the guage rises and drops slowly which I dont feel is consistent with an under pressurized pressure vessel.
The automatic air vent valve does I think need checking if only to rule it out. I've experienced a faulty AAV valve on my old boiler and it was totally ineffective, jammed in one position and the 'float' wouldn't move.
I've decided to call Bosch as the boiler is under 5 year warranty and despite the previous post, if the boiler is drawing air into the system and/or failing to vent it well that's what a warranty is for.

Final thanks to everyone who posted helpful comments - No further posts required.