Solve your radiator problems

Date published: 21st February 2018

With the cold weather continuing, it’s important to stay warm. We get a lot of calls about broken radiators, but often it’s a small problem that can be fixed yourself without having to wait for an engineer.

The first thing you need to do is identify the problem.

  • If all the radiators in your house are cold or lukewarm, this is likely to be a problem with the whole heating system, such as a boiler malfunction.

What do I do? Report this to us on 0115 916 6066 (during office hours) or 0115 915 2222 (out of hours). Total loss of heating counts as an emergency repair, and we will aim to be with you within 24 hours.

  • If you have a problem with one radiator and there is also an accumulation of water underneath the radiator, your radiator has a leak.

What do I do? Try turning your heating off, then tightening the nut(s) on your radiator’s inlet valve. If this doesn’t fix the problem, the nut may be corroded and will need to be replaced.

  • If the radiators on the upper floors of your house aren’t heating up but the radiators on the lower floors are, your heating system may not be operating at a high enough pressure to get hot water to the top floors of your house.

What do I do? You may need to top up your boiler with water. You can do this using the lever or tap on your boiler, known as the filling loop.

  • If your radiator is entirely cold, or cold at the top, when your heating is on, there may be a build-up of cold air inside it.

What do I do? You can normally fix this problem by bleeding the radiator. Bleeding radiators makes them more efficient, meaning a warmer home and cheaper energy bills. 


How do I bleed a radiator?

  1. You will need a radiator key to open the small valve at the top of one end of your radiator. On this valve, there will usually be small square bit which can be turned to adjust the valve. Radiator keys, which are  metal implements designed for opening and closing radiator valves, are available cheaply at most hardware stores. Find a radiator key that’s the correct size for your valve or, alternatively, search your tool chest for a small wrench or other tool that’s the right size to turn the valve. Some modern radiators are equipped with valves that are designed to be turned with a simple flathead screwdriver.
  2. Turn off your heat. Ensure that your central heating is switched off before bleeding, as an active heating system can introduce more air into the system. You want your radiator’s contents to settle completely before releasing the air trapped within. Allow time for the heat in your system to dissipate, then feel all over your radiator for heat. If any part of your radiator is still hot, wait for it to cool completely before proceeding to the next step.
  3. Open your radiator’s valves. Ensure that both the intake and exit valves of the radiator are turned to the “open” position. Then, insert your radiator key (or screwdriver, etc.) into the the bleed screw in the bleed valve at the top of the radiator. Turn the screw counter-clockwise to open the valve. You should hear a hissing sound as air escapes from your radiator.
    • Opening the bleed valve allows trapped cold air to escape, which is replaced with liquid from your heating system via the pipes connected to your heating system.
  4. Catch drips from the valve. As air escapes from your radiator, water will likely sputter from the bleed valve. Hold a kitchen towel or cloth under the bleed screw to catch any drips. Alternatively, use a small bowl or dish.
  5. Wait for water to squirt out of the bleed valve. When a steady stream of water (not a sputtering mixture of air and water droplets) squirts through the bleed valve, you’ve released all of the air trapped in your radiator. Re-tighten your bleed valve (turn the bleed screw clockwise) and ensure that there are no leaks. Use a rag to wipe up any water that’s splashed around your radiator.
  6. Repeat this process on all the radiators in your house. To ensure all excess air has been drained from your heating system, it’s best to bleed all of your radiators, even if you’ve only been having problems with one. For a well-maintained heating system, you should try bleeding your radiators regularly. An annual bleeding plus a bleeding after any repairs or modifications to your heating system is usually plenty.
  7. Check your boiler’s pressure level. By releasing excess air from your radiators, you’ve lowered the overall pressure of your house’s heating system. If the pressure’s fallen too low, heat might not reach some of your radiators (especially ones on the top floors of your house.) To restore your heating system’s pressure, it may be necessary to top up your boiler with water. You can do this using the lever or tap on your boiler, known as the filling loop.

Click here to see U-switch’s step-by-step guide to bleeding a radiator.

If you are reporting a broken radiator to us, please tell us what kind of radiator it is (e.g. hot water radiator or storage heater), how many radiators are not working, and whether there is a leak.