air in pipes

[dougyr]

Hi, I have glowworm energy saver 30e boiler (serviced 6 months ago)fitted as a non pressurised system now my problem is that i seem to constantly have air in the system making the boiler but mainly the pipes which run through our bedroom noisy.
I usually have to bleed the system weekly and its the same couple of radiators everytime, in the bedrooms
There is inhibitor in the system, the header tank is full, I have bled the pump, checked and tightened all the glands on the rads & pipework valves and checked the joints round the boiler (which is the garage).
the only other think is possibly the vent pipe to the header tank in the loft the pipe is hot for the first 6ft above the pump but in the loft it is cool, if it is the vent line then how do I prove it is and what can I do about it any answers much appreciated, this is not a new fault its been ongoing for some time now
many thanks

Dougy

 

[hi-spec plumbing heating]

your vent pipe maybe drawing in air
stick a glass of water under it and run the system and place the vent into the water see if it draws it in if so it's drawing air in.

 

[dougyr]

thanks for a quick reply have set up a glass with water and marked the level will give it 24 hrs and see if there's any change


thanks
Dougy

 

[dougyr]

hello again

i checked the glass this morning and the water has gone down about an inch suggesting air being sucked in through the vent, so what can I do about about this, also I've checked all the radiators for air and there is none but every time the boiler fires up I can here the bubbling sound running through the pipes its very noisy just when the boiler is running I've tried draining some water from the only radiator not fitted with a trv theres plenty of pressure there but the water is quite black, would this suggest possibly a hydrogen gas problem as well although the water was not that smelly, again any suggestion appreciated

Dougy