Coffee mug with gloves and Autumn leaves

Why is one of my radiators cold?

Autumn is upon us, the evenings are drawing in and the weather is decidedly cooler. The chances are that you have already started turning on the heating from time to time. If you have, and you have noticed that one of your radiators is not heating up properly or is completely cold, don’t panic - here are the common causes of this problem and how to fix it.

Check that the radiator controller is set correctly

It may seem obvious, but sometimes we panic and forget to check the basics. Assuming your boiler is working properly, the first thing to do is make sure that the radiator thermostat (the thermostatic radiator valve, also known as a TRV) is set to the desired temperature. This is easy to see on newer controllers, which are usually marked with numbers, icons and even colours - but it can be much harder to tell on older controllers.

The TRV is usually located on the bottom left of your radiator. Turning it clockwise will turn it off, while turning it anti-clockwise will turn it on. Turn the TRV as far as possible in an anti-clockwise direction and allow time to see if the radiator heats up.

If you find that you are unable to adjust the thermostat, you may need a replacement. We’d recommend speaking to a heating engineer if this is the case.

Do not confuse your TRV with the lockshield (also known as a balancing valve). This will be located at the base of the radiator on the other side. It is much smaller and generally can’t be adjusted by hand.

If you have had your home fitted with smart controllers, you may need to refer to the manufacturer’s handbook. Check that you haven’t set the radiator to a different zone or turned it off.

Check for air in the system

If you’ve checked that the TRV is working and set to the desired temperature and your radiator still stays cold when you are expecting it to be warm, the next thing to check is for air in the system.

Air in the heating system tends to gather at higher points and prevents the correct distribution of heating water, leaving you with radiators that don’t heat up at all or only heat up partially. Luckily, this particular problem is usually quite simple and straightforward to resolve with the following steps:

  1. Set all radiator thermostats to maximum and run the heating at full temperature for 10-15 minutes with all radiators on
  2. Turn the circulation pump off and wait until the radiators are cool - usually 30-60 minutes
  3. Bleed the radiator nearest the boiler using a bleed key or screwdriver until water comes out
  4. Repeat this for each radiator
  5. Turn on the boiler and check the water pressure

In most cases, this will solve the problem. If you are unsure about bleeding the system or encounter difficulties at any point, it is recommended that you contact a professional engineer.

Looking to replace or service your boiler? D.R. Plumbing & Heating have been serving the North Wales region for over two decades and specialise in gas and oil boiler installation. We enjoy a reputation for our friendly, professional and prompt service along with excellent workmanship. Call today to book a free, no-obligation quote. If you would prefer us not to visit you at home, we can also assess your boiler and prepare a quote by video call.

Call now on Wrexham 01978 291 923 or Mold 01352 620 125.

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