I have air in my system when water is heating and I’m told to turn heat and water on to push the air to the rads, the plumber said it’s a myth that you have to turn heating off to bleed BUT it’s a safety thing. Do you ever bleed with heat on?
A very detailed explaination of bleeding your rads https://www.viessmann.co.uk/heating-advice/how-to-bleed-a-radiator I would just do it with the heating turned off, and repressurise as needed tbh. It’s air, so it rises and will normally sit at the top of the radiators.
Considering that Veissman is a heating manufacturer, I am surprised that they would publish a pageful of garbage. The reason that one turns the heating off, is to stop the pump. This allows the water to find its own level. Also, on some older systems, some of the rads can be under negative pressure with pump on - you can suck air IN to the rads with the pump on. OP: Exactly what is the problem? Is there a an actual malfunction, or just noisy?
When the water is heating there is loads of air (gurgling) I haven’t had the heating on for months obviously and the plumber who replaced all my TRVs a month ago said try running water and heating together for an hour to push air up to rads.
Agree and definitely can suck in air on some systems, we have one at work that does so if we don’t turn the pumps off, but viessman do tell you to turn the heating off when u bleed it, although they say it’s so u don’t burn yourself lol, when I would say it’s cos it can suck air in and actually with the pumps on the air won’t be settled it will be being moved about.
Have you tried venting radiators yet, just do it when the systems cold and everything is off. Start on the ground floor and work your way up. If your system is fed by a tank in the loft it should top itself up. Also if you have a immersion type cylinder in the cupboard there may be some air vents in there too that could be automatic but also may need manually venting.
If you have a " normal" system with the pump sucking the flow out of the boiler and then pumping it around your distribution system you won't be sucking any air in so bleed with heating on or off it won't make any difference. Possibly with heating on any air bubbles in the distribution pipework should be pushed forward and trapped in the radiators but if this should have already occurred if you have been running your heating previously.
Good point about the auto air vents. They are generally poor, and subject to leaks, which sometimes present themselves as crud on the valve. This then prevents normal operation. Also, many are found with the caps screwed right down, rendering them non auto. While on the subject, AAV's in lofts often allow air IN. If you hear one hissing, remove the cap totally and use a bit of leak detector solution, soapy water or spit to determine whether the valve is sucking or blowing. OP: We assume that the air/noise has started since the work was completed?
Yeah some of the AAVs are awful, plumb centres own brand ones for example. Normally will fit flamco ones but they even fail now and again.
So I sat sweating for an hour with the heating on, bled the rads, tried again, bled the rads, tried again… all was quite quiet, this evening the water came on to heat and after having a bath the noise is back, gurgling in the pipes
Did you look in the cylinder cupboard to see if there were any air vents in there. If you aren’t sure take a photo of it and the pipework and post.
Is yours a combi or an open system. The latter has a small header tank in the loft. If it does have a HT, observe the vent pipe above the HT while a second person turns on the heating. Does water discharge from that pipe? Is the HT warm (check now , there may still be warmth from earlier)