how do i bleed a radiator. I know i need a radiator key and i put in the side and unscrew, but when do i?

Question

tighten it again

Answer 1

When water starts to come out of the valve you have inserted the key into, so put some towels or something on the floor before you start.

Answer 2

The idea is to get the air out of the radiator so that it's full of water. So, close the valve when you're getting (maybe very hot!) water out and no more air.

This means you should also be ready with something to catch the water in, and if the radiator is hot you may want to hold the key with pliers or a gloved hand -- the water could be very hot as well. But don't overtighten if you're using pliers...

You may need to do this more than once over several days; sometimes the air won't all be in the right place to be extracted by the valve the first time.

Answer 3

You bleed a radiator to let trapped air escape.
By opening the valve on the end near the top the pressure of the water forces the air above it out through the valve. You should be able to hear the air hissing as it is expelled and close the valve as the water reaches the top of the radiator. Do not worry if a little water escapes but try to stop before too much gets out and wipe up any that does so!.

Answer 4

1. Don't unscrew it until the 'plug' comes out or you will have a job getting it back in.
2. Hold an old towel or something similar where you insert the key as hot steam/water will come out and could scald you.
3. You only do it if you have a 'knocking' in the pipes (possible air block) or parts of the radiator stays cold.............

Answer 5

Put the rad key in , undo it, listen to the gurgling and hissing (and if the heating is on like it should be you will feel the radiator get warm from the bottom up, then when water comes out and no more bubbles tighten it up. Don't be surprised if the water is black. If the rad is old you will get all the crap come out aswell

Answer 6

You only need to bleed a radiator if the top part is cold whilst the rest is warm
if you need to bleed it you loosen the bleed screw and allow the air to escape. When water starts to escape ,tighten bleed screw.
The top part of radiator should get warm/hot depending on your rad temperature.
Arthur

Answer 7

Further to all the other answers you should switch off the central heating pump first then start bleeding the radiator furthest away, at the end of the line, and work backwards so that you remove all the air from the system.

Answer 8

It's like bleeding any other liquid filled device: your goal is to get the air out with the least amount of fluid loss.
As soon as the air is out the fluid will begin coming out; that's when you retighten the the bleed valve.
An easy way to see when the air is finished is to take a length of hose/tubing that will fit over the valve where the air/fluid comes out. Attach one end to the valve with a worm clamp before you ever start. Drop the other end into a jar with a couple of inches of water in it. When you open the valve, you'll see bubbles coming out the end of the hose/tubing. When they stop, then the system is bled out. The advantage of this is you don't suck air back in if a vacuum develops and when the water does come out, then it goes in the jar.

Answer 9

I done one of mine a few weeks ago. Make sure the central heating is off, undo with key and make sure you have a bowl and cloth with you. The water will come out (maybe a bit dirty!) and some air. Screw up again and you radiator will be nice and hot when you turn heating on again

Answer 10

Insert key into bleed valve, unscrew slowly. Allow air to escape, stop unscrewing once the air starts to come out, once water starts to dribble out cose by screwing up bleed valve.