B l e e ding of radiators

Can anyone tell me please how to B l e e d central heating radiators?

Our master radiator in the hall feels hot at the bottom of the radiator but cold at the top.This radiator we were told by the builders controls through the thermastat all the heating in the house,though on all the other radiators have those heat control thingys fitted to them so we can control how much heat each radiator pumps out.

I know that the master one has possibly got an air lock in it so needs the air releasing.I have a small brass key that fits in one end of it at the base of the radiator.Can someone tell me whether it is best to bleed this radiator when the heating is switched off?

I have seen Mr K do it where we used to live and he caught any water that came out in a container.I keep asking him to do the master radiator but so far no luck so I am going to do it myself.Even for a blonde like me it can't be that hard to do.

Any suggestions will be gratefully recieved

PS I hope that I have explained it ok to you all

 

You needn't turn it off, just make sure you don't burn yourself 'cos it will spit hot water. Hold a container under the hole with the square fitting in it. Put the key in and carefully turn it. If it won't turn one way try the other but make sure not to apply enough pressure to snap the key. When it starts hissing then watch it and when it really starts spitting out water then tighten it again. Finito.

 

Hi John,I did as you said but the water started coming out without any hissing noise so I ahve relocked it.There is a small key bit at the top right hand side but when I put the key in that one even though it fits I can't turn it as it looks like it is painted,so it won't turn.

The one that I have been trying to sort out has like limy cyrstal stuff coming out of the pipework and has set so I have just been removing that.

I might have to take some photos to show you what I mean.The bottom of the radiator is definetly boiling hot whereas the top is stone cold.
I never heard any hissing as or spitting of water on the bit that I was turning so I assume the air isn't the problem.

Thanks for your advice.Methinks I need to go to evening classes to learn all this sort of stuff if they still do them that is :D

 

This is the master radiator...



This is the bit where I fit the key..



And this is the one on the top right hand side that cannot be turned with the key...



I have felt the radiator and the top is now getting hot,though I have had to give up for the time being as the brass key and my fingers were getting burnt.I will check it later to see if letting some of the water out has helped.

 

Sorry, but under normal circumstances you bleed a radiator at the top, so like it or not the top is the one you need to find a way to turn.

 

If you are getting burnt then turn the C.H. off. and of course Palustris is right, you always bleed from the top, cos that's where the air is, 'cos it's lighter than water. :D

 

Yep that is what I have done with mine, turned the one at the top. A plumber always told me i should turn off the heating so the pump goes off - I think it allows the air to gather.
Another thought - mine wasn't coming out once with a hissing sound.
What sort of central heating system do you have? Do you have a tank in the loft that tops up the system?
Mine was changed and works as a closed system rather than having a top up tank. It wasn't hissing because the pressure had dropped and i had to open a valve from the cold water system to get the pressure up, watching a dial on the water pump carefully.

 

Geoff. I too have a closed system. reckon they must vary as well. Never had a pressure problem. I seem to remember that it's automatic. If it isn't I want my money back 'cos I seem to remember that that is what I paid for.

 

I reckon that bottom one, incorporated into the rad valve, is for draining the system down, the top one is the bleed valve for that rad and MAY be a different size key.

 

If only the bottom half of a radiator is getting hot and when you open the air valve you get anything other than water out it's time to call a plummer to get the system cleaned out.
If the pump is not up to scratch, that can cause a problem. Start the central heating up and listen to the pump, it should run at a constant speed indicated by an unchanging humming noise.Any change in the pitch means the pump is struggling to send water around the system.
Radiators have to be 'balanced' or some may be 'robbing' others of pressure. To balance a system, turn all radiators off (if radstats are fitted do it from the other end of radiator) so that no water can flow. Turn on each radiator say, half a turn and move on to the next. Do this until all rads are hot.
Hope this is of some help.

 

Hi everyone,just to let you know that Mr Kandy has finally solved the problem.He used the brass key on the top right hand bleed valve and some air came out.The radiator is now red hot all over. Thanks for your help

Terrier,our house is only six years old but we have already had to have a new circuit board or two because the one that came with the Potterton Boiler wern't man enough to do the job.It has all been talked about on BBC1's Watchdog programme :rolleyes:

 

Precisely. And if that had failed you could have tried kicking it.

 

blimey, i never knew you had to 'bleed' from the top. we occasionally have problems with 2 of our radiators but have always bled from the bottom! Causes a nice stain on the wallpaper & carpet :(
i've just looked at the radiator in here, & can't see a 'key part' at the top but our system is really old so maybe they weren't made then.
didn't even know about master radiators!
when we win the lottery i'll get it changed :D
Glad you're sorted Kandy
Cheers
sandra

 

we learn something new every day sandra on GC,

 

That top one you are showing Kandy is not a bleed valve you need to replace it with a proper bleed valve, you can get some that are automatic bleed valves, the crystal stuff at the bottom is a slight weeping on the compression joint usually they seal themselves with the heat from the rad.