Bleeding and balancing radiators

We’re all looking forward to the summer, but we’re not quite there yet. With that in mind, here’s how to make the most of your central heating by bleeding and balancing radiators. Do you have cold spots in your home? This could mean your radiators need a little TLC. If some are heating up more than others, it could be due to the following:

  1. They need bleeding
  2. They need balancing

Fear not – both are easy DIY tasks!

Let’s try bleeding first.

It’s not as scary as it sounds! ‘Bleeding’ is letting out air that is trapped inside a radiator. Doing so can really improve the efficiency of your heating system.

How do I bleed my radiators?

1. Turn your heating on. The radiators need to be hot in order to build enough pressure to force air out.

2. Pinpoint which radiators need bleeding. Being careful not to burn yourself, identify cool spots in your radiators – this could mean there’s air or gas trapped inside. These are the ones that could benefit from bring bled.

3. Switch off your central heating. Find the bleed valve (normally at the top of the radiator) and open it with a radiator key or flat-blade screwdriver. Lay down a towel down to catch any drips. Hold the key or screwdriver with a cloth and slowly turn it anti-clockwise. If gas is escaping you’ll hear a hissing sound. Then liquid will come out and you need to close the valve quickly.

4. Look at the gauge on your boiler to check pressure. If you need to top up, you can do so using the lever or tap on your boiler (the filling loop).

In the video below, you can see James bleeding a radiator at his home.

If this doesn’t help, you might need to try balancing the radiators next.

What is balancing?

Hot water reaches some more quickly than others, as it has less pipework to travel through – those nearer the boiler will usually heat up quicker. This means you may need to ‘balance’ both valves of your radiator to the same temperature, by turning the lock shield. This is a valve usually found at the bottom of your radiator, the opposite side from the temperature controls.

What will I need?

  • Radiator-bleeding key
  • Lockshield valve adjuster or adjustable spanner
  • Digital thermometer
  • Screwdriver

How do I balance my radiators?

1. Turn off your central heating and allow radiators to cool down.

2. Find the lockshield. It will be on the other side of the radiator to the thermostatic radiator valve or temperature adjuster. it usually has a push-on cap.

3. Open your wheelhead or temperature adjuster as far as it will go. Open the lockshield with a spanner by turning anti-clockwise.

4. Turn your central heating back on and note down the order the radiators heat up; the first will probably be those nearest the boiler. Turn the heating off and wait for the radiators to cool down.

5. Once they’ve cooled, turn the heating back on and, starting with the first radiator on your list, turn the lockshield valve clockwise until it is closed and then open it by a quarter of a turn. When the radiator warms up, take a temperature reading at the pipework leading to one of the valves.

6. Next, take a temperature reading at the pipework leading to the other valve. You need to open the lockshield valve gradually until there’s a 12°C difference between now and the reading you took before. It might take a couple of minutes for the change to happen.

7. Next, check the rest of the radiators in the system following the order in your list. The lockshield valve will need to be opened more the further you move away from the boiler; for some radiators it may need to be opened fully.

Hopefully this will help!

Think we missed something? Do you have a different opinion?

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