How to balance radiators

If you find that some radiators in your home take a lot longer to heat up than others, it’s possible that your radiators need balancing. Radiator balancing, also known as hydronic balancing, involves adjusting your radiators to ensure an even distribution of heated water to each radiator.

When do you need to balance radiators?

If your radiators aren’t balanced, the hot water from your boiler is not being evenly distributed; your radiators are all different distances from the boiler and those nearest are likely getting the most heat and those furthest away are getting the least.

Note: Balancing a radiator is different from bleeding a radiator, which is intended to fix a single radiator that is not heating up evenly (or in some cases at all) because air is trapped inside.

Balancing radiators involves attending to every radiator in your house so it can be a fairly time consuming task but could make a big difference to your comfort. When you have new radiators, valves or central heating work carried out the engineer should balance your radiators for you so they heat up at the same rate. It’s a more complex task than bleeding radiators requiring a digital thermometer and a tool to adjust the usually fixed lockshield valve (this is different to the valve you use to turn the temperature up and down – find out more in Radiator Valves Explained). For this reason you may want to find a professional heating engineer to make sure the job is done properly.


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However, in case you are a confident DIY’er, we’ve put together this quick guide to balancing radiators to help.

What tools are needed?

  • Radiator bleeding key
  • Digital thermometer or multimeter with thermometer function
  • Lockshield valve adjuster (or adjustable spanner)
  • Paper and pen

Step by step instructions

  1. You should start by turning off the heating system and letting it cool completely.
  2. Once it has cooled you should bleed your radiators to remove any air which has collected in them since it can cause the radiator to heat unevenly. For more information and instructions visit our guide to bleeding radiators.
  3. You should familiarise yourself with the valves on your radiators – these may differ between radiators of different ages and models. Generally a lockshield valve will have a cover – remove these covers and open all of these valves fully by turning them anticlockwise. You will also need to open the thermostatic radiator valves (TRV’s) to full. Whilst wheelhead and thermostatic valves can be turned by hand, lockshield valves will need a special adjustor or adjustable spanner to do the job.
  4. From here you may want to grab a pen and paper or create a spreadsheet and make a list of all the radiators in your home.
  5. Turn the heating back on and write down the order in which the radiators start to heat up – it’s likely that the ones nearest the boiler will be first. This will give you an indication of the order in which hot water reaches each radiator, numbering them can make the process a little simpler.
  6. You can then turn the heating back off and wait for the system to cool once again.
  7. Turn the heating back on and go to the radiator on your list which heated up first.
  8. You can then turn the lockshield valve clockwise until closed and then open it again by one quarter of a turn.
  9. Once the radiator has heated up you will need to take the temperature of the pipe leading to one of the valves and note this down.
  10. Now take the temperature of the pipe leading to the other valve on the radiator. Then open the lockshield valve gradually until there is a 12 degree Celsius difference between this and the last temperature you took.
  11. Now repeat this for each of the radiators in your home and this should result in a balanced system.

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