How to Bleed Air From Radiators
Air can often build up inside your central heating system, this can prevent radiators from heating properly and reduce the efficiency if your central heating.
There are a couple of ways to tell if your radiators need bleeding. If they are taking longer than usual to get hot, or you can hear gurgling noises as the water passes around the system.
If so, you need to bleed them to let the trapped air escape and the hot water to circulate freely once again.
its a simple job and anyone can do it. Here’s our a guide on how to bleed the air from your radiator
Tools Required
Identify the blocked radiators
First you will need to find which radiators have air which is preventing the hot water flowing around your central heating system.
The easiest way to check if your central heating system needs bleeding is to see if your radiators are cold at the top but are warm at the bottom.
Turn on your central heating and allow is to run until the radiators are warm.
Feel the top of the radiators with your hand taking care not to touch areas that are too hot.
Any radiators that are cold or cool to touch probably have air trapped inside and they need to be bled.
Things to Check Before You Start
If you have several radiators that need air bleeding from them, it is best to start with the radiator that is furthest away from your boiler.
If you have to bleed radiators on more than one floor, always start with the radiators on the lowest floor first, then move up to the next level.
Always bleed your central heating when it is cold. turn off you central heating and allow the heating pump to stop and your radiators cool so that the air can settle.
If your central heating system is pressurised, remember to check the boiler pressure once you have bleed the radiators and refill the boiler as required.
How to bleed the air out of your radiators
Once you have identified which of the radiators in your central heating system need bleeding, follow our guide below
Step 1:
Turn off the central heating and make sure the radiators are cold.
Step 2:
Use an old rag, or a small jug, to catch any liquid and hold them under the bleed valve, which is fitted at one the top of the radiator at one end. Then insert the radiator bleed key or a flat head screwdriver.
If you don’t have a rad key, then read our associated article on how to bleed radiators without Radiator Key for more help
Step 3:
Open the Bleed valve by turning it anti-clockwise, do this slowly until air starts to escape, the air will make a hissing noise as it passes the bleed valve.
Step 4:
Once the air has gone and water starts to leak out, close the bleed valve by turning the key clockwise.
Step 5:
Repeat this process on all the radiators that have trapped air, working towards the boiler.
Step 6:
To check the radiators are working turn your central heating back on and leave the system to warm up for a few minutes then run your hand over the areas that were previously cold, they should now be warm.
Find out more about central heating and plumbing in our other great Plumbing articles
This article was written by: Richard Quinton – The DIY Help Desk Owner, Engineer & technical specialist.
Richard is one of the key partners in The DIY Help Desk team. He is a qualified Engineer, writer, and publisher, educated to Master’s level. He is a keen advocate of DIY and home improvements.
Richard enjoys helping others to learn new skills and reach their goals and believes that passing his knowledge and experience on through his writing is an effective way to positively impact the lifestyles and well-being of others on a larger scale.
