How to bleed a radiator - and why it can help energy efficiency

What does it mean to ‘bleed a radiator?’ Well, this refers to the process of letting trapped air out of your central heating system.

Here we’ll explain how to do it and why it’s worth finding a few minutes to do so.

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Why should I bother bleeding radiators?

You’ll know that your radiators need bleeding if, when the central heating is on, you find they’re cooler or even cold at the top and hot at the bottom. It’s always worth checking this yourself, before going ahead and spending money on a plumber unnecessarily.

The temperature difference is brought about by air getting trapped in the central heating system. When this happens, the air is forced through your system until it gets stuck in your radiators.

These air pockets prevent the radiator working as efficiently as it should. Instead of a radiator full of hot water heating the room, only a partially filled one is operating. Having radiators gradually filling with air is a sure fire way of wasting money on your energy bills.

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How do you bleed a radiator?

1)     Check your radiators

First, you need to know which of your radiators need bleeding. Turn on your heating system and let the radiators heat up. If there are cold spots on your radiator, it probably needs bleeding. If you haven’t bled your radiators in a while, you may not even need to check; it could be worth just doing them all in one go!

2)     Turn off the heating

As we’ll see, bleeding a radiator can involve some water being released. If your heating is on, that water will be hot and you could burn yourself. It is therefore safer, to turn the system off and allow the radiators to cool before carrying on to step 3.

3)     Bleed the radiator

For this you’ll need the right tool which depends on your radiator type. Some radiators have special ‘radiator keys’ while others will simply require a flat edged screw driver. It’s also a good idea to have a cloth or a bowl to hand to catch the drips – beware the water can be dirty from sediment in the system.

Gently turn the key or screwdriver until you hear a hissing sound. This is the sound of air escaping. You may even hear your radiator bubble as water pours back into the space vacated by the air. Keep an eye and ear on the valve until you see water starting to appear and the hissing stops. When this happens you know all the air is out of the radiator and you can tighten the valve back up again.

4)     Turn the system back on

When you turn the system back on, the radiator should now heat nice and evenly. Some systems have a pressure gauge which can be found on your boiler. If your pressure is low, you may need to top up the system. This is usually done by turning a tap or lifting a lever on your boiler -be sure to read any manufacturer’s instructions before you do this.

With all your radiators bled, it’s time to snuggle up with a good book or your favourite TV programme and enjoy the warmth.

For other tips on how to save energy in your home, have a look at our tips today or if you want to save on your energy costs in other ways, why not see if you can switch to a better deal?