How to clear air from a central heating boiler

If your central heating boiler is making air like noises and shutting down after firing for just a few minutes or just not firing up at all. Then air could be your problem air that is stuck in the boiler. This often happens after you have drained down the system.

[helenhughson]

OMG I think we fixed it. After a freezing Saturday night and not being able to get an engineer out! Thank you so much!

[orsoch]

Thanks for the video. I had a new rad fitted and had to drain down. even though I'd bled the rads and pump the clanking from the boiler was horrendous. I've always been scared of boilers since being terrified of those things people had on their kitchen walls in the 60's. This vid gave me the confidence to have a go. It took two goes but it cleared the air and the boiler purrs like a kitten now. A big thank you!

[nevergiveupever]

Hi. I have air in my combi . I recently redid my bathroom and put a heated rad above the boiler . The boiler is downstairs and the towel rad us in the bathroom directly upstairs. Ive been having pressure loss problems so was going to change the expansion vessel but prior to that i changed the pressure guage as i suspected it was faulty. Now it seems to be drawing air into the boiler and keeps locking out. I tighten the bleed screw on the towel rad as this is the highest point and i thought that had solved the issue but after a day im losing system pressure again. I have a feeling the diverter valve is holed. Do you think this could cause the system pressure loss after a few hours?

[MrPhillAsh]

I think this just saved me a whole lot of money! Thank you sooo much for posting this!

[barryhughes]

Dereton33. What tops up the water in the boiler, isn't it in a closed loop? I know the ball cock in the tank tops up the tank, but that water is heated up from the coil inside which in turn is heated up from the boiler. I'm confused and any help would be gratefully appreciated, and thanks for the video.

[larsuk]

Thanks for the video. I have similar symptoms on my boiler and notice there's a drain valve attached to the flow pipe (going out of boiler). Is that the one to use? Thanks

[Colin]

I have had a new 3-port valve fitted by a plumber, but the heating system is noisy now, like a rushing of water in the pipes near where the hot water tank is ! also had a loud bang from the airing cupboard and a loud rumbling/creaking sound ( a bit like a large tree being felled) immediately following the bang ! but the heating system is now much noisier than before ! The airing cupboard is immediately above my living room ! so very noticable ! just to add that the heating works ok as does the hot water ! the 3-way port valve fitted is an ESi ESZV223P model, I have been told they are made by Honeywell, is that correct ? Thanks.

[tidalthames]

Hello again.
I have looked for a drain cock near the boiler and there isn't one. In my kitchen where the boiler is, I have a radiator with a drain valve on it, which I have used many times to drain the system. Would using this work to remove the airlock?
Thanks for your videos, I have found them useful.

[jjmmjj]

Hi, hoping you can help.
My combi valiant is banging with hot water on, the pressure gauge goes mental, 3-2-3-1-4-0-3bar
Hot water is lovely when the tap is just cracked open, but opening more it'll run cold
I've got 2 radiators which are cold at middle/bottom but hot at the top
piping is 8mm micropipe all around so guessing rust/sludge/limescale has blocked pipes, boiler overheats and locks out?
In the winter months spotty heating that turns off and water that goes hot/cold isn't the nicest thing :(

Any ideas I can try as a home DIYer as money is tight after Christmas?
Cheers!

[malcolmkilpatrick]

Hi Mate,

Really useful vid, I drained down the system and replaced two rads on an F&E system. One of the rads is getting flow but no return the other is fine but the boiler keeps locking out due to air. I don't have a drain off in the airing cupboard or one near the boiler so I'm struggling to get it out. I've bled everything including the pump. Is there another way?

[zebadeez]

Thanks so much!! now I sorted that terrible banging clonking noise that's been driving me mad! good man!

[colsuemeg]

5* for a simple clear video. Thanks for posting. 👍👍

[mrb]

When I drain the boiler via the drain valve do I open the filling loops

[TRISTANorTRIS]

Hi. i know its a comment on a old video but I'm having this issue. After unblocking a blocked cold feed and flushing the system my boiler has lots of air above it. Gurgling and sloshing away. I had it running fine whilst running the cleaner through but after the recent flush i cant seem to get the air out and the boiler sometimes kicks in but more often than not goes to ignition lockout.

Its a gravity feed with a baxi solo.

I've tried bleed valves around hot water tank
Bleeding the pump whilst running
backfilling the system from drain on rad
opening drain valve above boiler as this video suggests (this does sound like air is coming out) Boiler RETURN
opening valve on mag filter (sometime appears a shot of air comes out) boiler FLOW

but same symptom exists.

Turn boiler on, you can hear the boiler spin up and slosh air up from the boiler, then it tries to ignite 3 times and goes into ignition fault mode.

Question is....

could I possibly back fill from the boiler return from garden hose?

many thanks

tristan

[robertpiggott]

thanks for the video....did not realise there was a drain plug next to boiler...

[stumay]

You sir, are a hero. Very useful videos

[UmarKhan-wwjl]

Dereton I need help, I have a Baxi Combi 25 and my boiler makes banging noises and my pipes all rattle after 3 hours of heating on, how do I solve this? Thanks

[rictiger]

Thanks for the tips. Would you need to replace any of the inhibitor in the system or would it be ok as you're not draining too much out?

[indianapwnz]

I drained my whole system a few days ago and it was working, there was some odd noises though :) Today I noticed the pressure was a bit high so let some water out, the needle didn't move, the thing is drained but it still says 1.5 bar... when I open the bleed nipple in the rad next to me water comes out so it's not emptied, i tried opening all of them when draining it the first time and it went to 0 no problem, any ideas what might be up Mr Dereton ? Cheers :)

[dip_art]

Thanks for the video. I've changed the 3-valve repair kit, so drained the water completely and filled again. Lots of air was running between the boiler and pump and the nearest radiator. There is auto air valve over the pump, most of air gone out from there but the same sound appears again after using hot water. I dont know if I found the right valve that you mentioned, but I drained 1 or 2 liters of water. Now more than half of the gurgling sound disappeared. All radiators are ok except the nearest one, it's like water is dripping to that one although there is no air in it. The maintenance book talks about a "hot water heat exchanger went screw" and I also got it loose but not much longer because its place is terrible, there are cables under the screw goes to main unit. And I gave up :))