Air in CH system
Discussion
Hay all,
Just wondering if anyone can give me some advice.
I've got an old style central heating system with a small baxi boiler in the base of the chimney, hot water is gravity fed from a big tank.
Ever since I first moved in (6 years ago) I've had a problem where air keeps building up in the system in one particular place.
It's just after the pump - diagram below:
Air builds up at the bleed points. Eventualy if I don't open the bleeds to release it then the air level gets down to the horizontal branch and the system gets noisy, sounds like running water all the time, if I leave it longer the next thing that happens is that the rads go cold.
Last summer I found a leaking/corroded pipe nearby and replaced it, afterwards I ran the system with two different cleaning/flushing products in it one after the other according to the instructions on each, flushing the system through after each then finally filled it up using a corrosion inhibitor (fernox I think it was)
Since then it's been a lot worse! It used to be once a month I'd have to bleed it but now it's once a week at least, and I can hear little bubbles moving through the system all the time though they don't build up in any rads.
At the same time I took up all the floorboards to look for more obvious leaks but couldn't see any
What should I do next? I read about boiler kettling but I can't hear anything that sounds like that if I listen to the boiler. I've fitted an auto-bleeder to one of the bleed points to stop it driving me mental but I realise this isn't a very good solution long term.
I'm thinking that if air's getting in but no decent quantity of water is coming out then it must be on the suction side of the pump.... Should I try replacing the pump its self maybe??
Open to suggestions really!!
Thanks
Neil
Just wondering if anyone can give me some advice.
I've got an old style central heating system with a small baxi boiler in the base of the chimney, hot water is gravity fed from a big tank.
Ever since I first moved in (6 years ago) I've had a problem where air keeps building up in the system in one particular place.
It's just after the pump - diagram below:
Air builds up at the bleed points. Eventualy if I don't open the bleeds to release it then the air level gets down to the horizontal branch and the system gets noisy, sounds like running water all the time, if I leave it longer the next thing that happens is that the rads go cold.
Last summer I found a leaking/corroded pipe nearby and replaced it, afterwards I ran the system with two different cleaning/flushing products in it one after the other according to the instructions on each, flushing the system through after each then finally filled it up using a corrosion inhibitor (fernox I think it was)
Since then it's been a lot worse! It used to be once a month I'd have to bleed it but now it's once a week at least, and I can hear little bubbles moving through the system all the time though they don't build up in any rads.
At the same time I took up all the floorboards to look for more obvious leaks but couldn't see any
What should I do next? I read about boiler kettling but I can't hear anything that sounds like that if I listen to the boiler. I've fitted an auto-bleeder to one of the bleed points to stop it driving me mental but I realise this isn't a very good solution long term.
I'm thinking that if air's getting in but no decent quantity of water is coming out then it must be on the suction side of the pump.... Should I try replacing the pump its self maybe??
Open to suggestions really!!
Thanks
Neil
The problem may be due to gases builing up in your system rather than air. Try getting the system properly power flushed ( I charge £450 for a 7 rad system). The Auto vent you have fitted could allow air to be drawn in if it's on the negative side of the pump, you could have a blocked feed. I think you would be better off getting a decent plumber in. Good luck with it.
Gassing Station | Homes, Gardens and DIY | Top of Page | What's New | My Stuff