How To Balance Radiators

Tool List:

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

1. Make sure all the radiators have been bled. Turn off the central heating and allow the radiators to cool.

2. Familiarise yourself with the valves. This is the lockshield. It will usually have a push-on cap or one that is secured with a screw through the top. Remove it.

3. Older models will have a wheelhead valve, like this, on the other side — used to turn the radiator on/off.

4. Newer radiators will have a thermostatic valve like this instead of a wheelhead valve.

5. Open up the valves on all the radiators in the house by turning them anti-clockwise.Wheelhead and thermostatic valves can be turned easily by hand, but the lockshield will need a plastic adjuster to open it up (INSET PIC SHOWS INSIDE). These come with new lockshield valves. A spanner will also do the job.

6. Turn the central heating back on and note down the order the radiators heat up. Those nearest the boiler normally get hot first. If you’ve got a lot of radiators, get an assistant to help. Turn the heating off and wait while the radiators cool down.

7. When the radiators are cool, switch the heating back on and go to 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. Once the radiator has warmed up, take a temperature reading at the pipework leading to one of the valves.

8. Now take a temperature reading at the pipework leading to the other valve and open the lockshield valve gradually until there’s a 12°C difference between now and the reading you took in step 7 (allow a couple of minutes after each adjustment for the temperature to change). The temperature figures indicated in the last step and this one are relevant to the radiator shown – don’t take them as any kind of optimum figure – it’s the 12°C difference in temperature at the valves that counts. Next, check the rest of the radiators in the system following the order in the list. The further you move away from the boiler, you’ll find the lockshield valve will have to be opened more. The last radiator may need to have the lockshield valve fully open to work at full efficiency. Your radiators are now balanced and should work perfectly.

Getting A Temperature

A key part of this job is measuring the temperature difference across each radiator. Specially designed thermometers that strap round the pipes at either end of the radiator are available to buy or hire, but it’s not really necessary to use these. You can get away with a single digital thermometer — it just means that you can’t take simultaneous readings and you’ll have to move from one end of the radiator to the other.

Digital thermometers are available from around £10. Alternatively, some digital multimeters have a temperature sensor function. A digital multimeter with temperature function costs from £25 and can also be used for taking electrical readings and checking continuity in wires, among dozens of other functions.

Further Reading:

• Radiators
• Underfloor Heating or Radiators?
• How to replace a radiator
• Skirting Radiators
• Choosing the Right Radiator
• Will a Skirting Heating System Work as Well as Conventional Radiators?