Bleeding a radiator

bobbyss

Some questions please.

How long should you have the radiators on before you bleed them?

Which radiator are you to bleed first? I heard that you should start bleeding the one farthest away from the controls or something like that?

Thank you.

GreeBo

You can bleed them in any order, its when you are balancing that you need to start furthest away.

Once the rads are warm its fine to bleed them, you can even bleed cold tbh.

Note that depending on the amount of air you are getting out, you may need to top up the system (if you have a filler loop somewhere in the hotpress or near the boiler itself)

If you bleed them when hot and dont refill they can just suck in more air as the water cools and creates a vacuum.

bobbyss

N

https://www.boards.ie/discussion/comment/121362402#Comment_121362402

Thanks a lot. For an idiot like me could you explain the bit about 'top up the system'? 'refill them' ? What does that mean?

https://www.boards.ie/discussion/comment/121363189#Comment_121363189

There will be a small gauge showing the pressure of the system. Its typically located near or on the boiler. Aim for 1.5. If it drops below 1, you need to top up. Will look something like this

To top up there should be a valve you turn to allow the mains to refill the system. Note it literally only takes a few seconds, so its not a case of turn it and walk off. You need to be watching the gauge when you turn the valve

In my case the gauge is downstairs at the boiler and the valve is upstairs in the hot press, so its a 2 man job.

Loads of videos on youtube how to do it, its not a big job. The hardest part can be locating the valve that you need to turn

Furze99

I think some of the replies above assume you have a sealed or pressurised system with an expansion vessel.

Keep in mind that you may also have a more traditional vented system. This has a water feed from a small attic tank and an expansion pipe back to same. No dials or anything like that, the flow is controlled by ball cock on attic feeder tank.

We have system like this and to bleed, I always start at the highest radiator. Air rises in the system and most air gathers there. So bleed this first and then work you way around and down. Particularly applies to a 2 storey etc. If bungalow, usually one rad will just be a bit higher that others and have most air at top.

GreeBo

https://www.boards.ie/discussion/comment/121363524#Comment_121363524

When bleeding you don't need to start at the top as the air is not moving from one rad to the other as you bleed (unless your radiators have been plumbed in an interesting way!)

Its true that the highest rad will probably have the most air, but thats from air moving through the system under pressure and over time.