Air in wall heating - How to stop it sustainably?

Hello everyone,

my wall heating from is now in operation with our move-in. So far so good, it gets pleasantly warm - when there is flow.



Unfortunately, I notice that this heating circuit gets "clogged" with air once a day.

What the heating engineer has done so far:

[*]Flushed the entire HKV at the top twice
[*]Scratched around the head to see where the air could be coming from
[*]Suspect that it is because I deactivated the ERR, so other heating circuits are never closed to "blow through".

What I have been doing so far:

[*]Observing
[*]Observation is that at the beginning there was a lot of air in the system. The entire HKV bubbled and hissed. This was flushed away.
[*]Then some quiet, but also quite high outside temperatures. Adjusted the flow rates, heating curve etc. throughout the house. Complaint that the heating circuit again has no flow.
[*]After the second flushing usually no more noises.
[*]However, I have to close all heating circuits except the wall at the top once a day to "blow out" the air again. This works somewhat.
[*]Over 12-24h the air apparently circulates again until it clogs the heating circuit again.
[*]Call the general contractor, express my frustration and demand that the entire system be flushed and vented.

I would have thought that if you push the air somewhere else, it will eventually collect again at the highest point. In this case the pipe bends of the wall heating. Flushing everything should at least help. However, there will still be air in the pump, in intermediate pieces and elsewhere, which will eventually collect there again.

Since I have only installed a sludge separator so far, my approach now would be to have a (paid) microbubble separator, e.g. Flamcovent Smart EcoPlus, installed in the supply line. Of course, I will have everything flushed under warranty beforehand.

Would that likely work? The individual heating circuits can be turned off at the HKV so that water loss from opening the hydraulics should be limited. Alternatively, I would bite the bullet and have everything completely flushed and refilled. But only if the microbubble separator reliably catches and vents the air on the way up. I am not so sure if just flushing completely will be enough. Somewhere, the system will always draw or release gases over the years.

Do you have tips and experiences regarding this?

I think it is normal for the "heating water" to release some gas in the first few weeks. The question is, how does it get out of the system? Do the TRVs have ventilation valves? Or the hydraulics? "Flushing through" with fresh water does not sound like a solution because you are introducing just as much gas/air into the system as you remove. So I think it really is a good solution to have the ERR active for a few days/weeks to keep the circuit moving with enough pressure so that air bubbles cannot accumulate there and can then be vented accordingly via TRVs/hydraulics.

I have installed two quick vents in the system. Unfortunately, exactly where the flow velocity is at its maximum and only water comes through. These "vent nipples" on the HKV are also constantly submerged under water. I only know it from the past that you turn on the radiator and after a few seconds the air is out and with water you screw back on. But on the HKV, water appears immediately and in large amounts. I was very surprised. :D

I assume that the air is stuck in the several hundred meters of underfloor heating and is always pumped in a circle until it collects at the highest point = wall heating. I just don't quite understand why the air doesn't collect in the return buffer storage when I push it out again.

When I search on the internet for wall heating and air, opinions immediately come up that the heating system must be basically sealed. The heating installer must properly flush the system. Beyond that, you can control outgassing with the microbubble separator. The problem is that I currently have maxi bubbles in the system. I want the problem to be permanently fixed and not have the heating specialist come and flush every 2 years.

I personally find ERR for pumping the air around to be pointless. There must be 8 circuits (tried on the HKV) so that the air is pumped out. That should never happen with my underfloor heating design at NAT. In winter, when I need the wall heating the most, it would thus not work.

Does anyone in this forum have practical experience with wall heating or these separators?

Does anyone in this forum have practical experience with wall heaters or these separators?

I was advised against microbubble separators because they cost money and don’t provide any real added value.

I also had a lot of air in the system at the beginning. Tip from my heating supplier: keep the pressure in the system at least at 2.5 bar up to 3 bar. Run the venting program for a long time.
Result: For months now, exactly 0 air in the system.

Whether this can be transferred from the normal underfloor heating with a Panasonic monoblock to your system, I can’t say. But it’s worth a try.

I have found that quite a lot of air accumulates in the inlet pipe of the HKV, which I can bleed off. I will check it once a day now and then hope that my problem will eventually "disappear into thin air".

Were you able to get rid of the air yourself by now or did it need to be flushed again?