Air in the heating system

Air Source Heat Pumps (ASHPs)

Last Post by robl 3 years ago

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Mike Patrick

(@mike-patrick)

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Joined: 4 years ago

Posts: 172

Topic starter 08/12/2022 10:05 pm

Our underfloor (ASHP powered) system has air in it. I can hear water trickling through the pipework at night and every day canbleed air out of the heated towel rails.

I know this makes it less efficient and have an engineer visiting next week, hopefully to rectify it. He has already been once and identified that the pressure gauge on the heating expansion vessel isn't working so always shows zero pressure instead of what I'm told should be about 1 to 2 bar.

With the current very cold weather our electricity consumption has of course gone through the roof and I'm hoping to see some improvement from fixing this.

But how does the air get into the system? How do you eliminate it? There is no sign of fluid leaking out but the plumber thinks it should be topped up via the fill tube (which the installers helpfully put downstairs while the pressure tank and other pipework are upstairs!).

Grant Aerona HPID10 10kWh ASHP

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Cider

(@cider)

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Joined: 3 years ago

Posts: 1

09/12/2022 9:05 am

Few ways. Easiest is to isolate return manifold, close all zones (loops) but one and install hose to return drain point and open. Then open filling loop unit air clear. Repeat for each loop.
seemingly very few installers know yet alone do this

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robl

(@robl)

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Joined: 3 years ago

Posts: 203

09/12/2022 2:13 pm

These guys have "deaerators" that can remove microbubbles that are left flowing around a system, might improve matters. They also sell exotic "vacuum degassers" I think those need electric mind, to directly remove dissolved gasses.

Never used any of them myself, we have conventional rads with bleed valves all over the place- every time I have ever had the system emptied and refilled it has taken weeks to settle down and stop gurgling. When I refill it I wish we had a clever pump that jerked on/off as some now do to help clear air locks. It's only done every 5 years/never, so no worries. I've trawled around the website looking for pressure versus flow on them, they just say "low pressure drop".