What to do if One Radiator is not Working

It can be really annoying to find that one radiator out of the whole house is not getting hot. This is why we have produced a brief video telling you the possible causes and solutions.

Make sure there is no air in the radiator. Using a radiator key and a cloth, release any air trapped in the radiator. Remember to top the heating system up with water should it be a pressurised (sealed) system.

If the radiator is cold at the bottom it could be sludge in the radiator. Close the valves on the radiator, remove it and then clean out the inside with a hose until the water runs clear.

Always remember to check the lockshield valve on the radiator is open and that the TRV pin is not stuck down.


If the video has not helped you follow this easy guide below. We'll show you how to get the one radiator hot again.


  1. Make sure the lockshield is fully open. To do this, remove the cap from the lockshield. Open the lockshield by turning it anti-clockwise. Feel the pipes to the radiator to see if they are getting hot. If they are then great! You've solved the problem. Got a leaking radiator valve now? Click here to learn how to fix it.

  2. Make sure the TRV pin (or Thermostatic radiator valve) is open and not stack closed. To do this, remove the head from the TRV. Grab a pair of grips. You should see a small pin. Lightly loosen this pin by gripping it with your grips. Spray with lubricant to ensure it doesn't stick again. Feel the pipes. Are they hot? If they are then great! You've fixed your one cold radiator!

  3. Make sure the radiator is properly vented of air. Do this by using a radiator key and a towel. Release the air from the radiator. If nothing comes out and you're on a gravity system you might have a blocked feed pipe to the system from the loft tank. If you are on a pressurised heating system the pressure will need topping up.

  4. There is always the chance that this could be caused by an airlock. This is especially prevelant on 'drop down leg' radiators. Check out how to remove air locks from radiators here.


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