bleeding radiators

[Lindsay]

Hi all, need some advice on how to bleed some radiators, my central heating is run off a combi oil boiler so dont have a clue how to bleed the radiators. Any help or advice greatly appreciated.

Thanks Lindsay

[bagpuss]

buy a radiator key

[bagpuss]

Tesco sell them along with screwdrivers etc listen for the air hissing out

[Lindsay]

Thanks bagppuss, someone said though that you have to do summit to refill the water at the combi boiler and i dont have a clue about this. Any ideas?

[John Little]

Does your heating system have a top up tank or does it have a pressure vessel?

[Lindsay]

Think its a pressure vessel John

[John Little]

There will be a pipe leading into it with a small tap. If you bleed your rads then you need to let some water into the pressure vessel. There should be a dial and a needle and you should have at least '1' on the dial. That should do the trick.

[EDDIE]

Look at the gauge on the boiler it should be at 1.5 bar if you bleed it the pressure drops or if u have leak the pressure will leak over time you should have a tap underneath your boiler you turn it fill up with water and then turn it off when it comes to 1.5 bar on the gauge it there should be a wire braded hose that goes into it but you should always keep an eye on the gauge and top as nessary?

[Lindsay]

Thanks all for the advice, One last question on the radiator itself where abouts is the valve that the water will come out once the air has gone, sorry really daft questions i know but i only ever had electric heating before.

[John Little]

At the top of the rad on the side.

And when you bleed, do it with a huge hank of kitchen towel - the 'gravy' that can come out is filthy.

[Phill]

This bit is yer valve you want to bleed:
http://www.diydata.com/problem/central_heating/bleedvalve.jpg

You wanna do something like this:
http://t1.gstatic.com/images?q=tbn:ANd9GcQZQ9-h5F6zgTVIxC2Vb1DXYF0fd7o617Xa8ALGMTW90u1u-9HW

You might find you'll need a pair of pliers to help turn the valve if it's stiff.
Don't be tempted to wind it all the way out, half a turn should be enough.

[Lindsay]

Sorry for being thick John but at the top of some of my radiators i have the dial to adjust the temperature and at the other end is the little square head with the slit in it that you could turn with a screwdriver. at the bottom i have a sealed end and an end with a hexagonal opening. The other radiators have a temp dial at the bottom and another dial at the other side which i pressume is to allow the water to flow round the system with a square slot end at one side and a hexagonal end at the other side.

[Lindsay]

Thanks for the pics Phil that makes it clear now :), should i turn off the combi boiler whilst i bleed the radiators or leave it on.

[Phill]

I generally do it whilst the system is running, actually heating the rad's. Do it just as it starts though otherwise you can get scalded by the water, If your not sure do it whilst it's switched off.
You may find you have to go round twice.
Before you start make sure you have found the filler loop & valve in or immediately by the boiler. Most systems will shut off if the pressure drops too low so if you can't refill your system you could end up with no heating at all if you have a lot of air to bleed out.

[mrlennie]

hey try to leave the heating off as your bleeding as it can pull more air in. Bleed then put heating on for 5 mins. Turn off then bleed again. Repeat till you free of the gases :)

Good to have a spanner with you as well in case the bleed valve is locked up and it tries to take the whole valve round with it ( it happens) then you can tighten. Any questions on what I just said post and I will try to explain better.

[Walter Ego]

Stating the obvious, I know, but just a reminder:

Hot water can be hot.