Heating and Radiators

A quick guide to problems with radiators and how to resolve common heating issues

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We get lots of questions about radiators, and why they aren’t working like they should, so we thought we would give you a quick run down of the most common problems and the cure for them.

We have lots more useful information on heating and plumbing on our main site, so either follow the links in this blog post, or click onto our main site, go to Projects and search for whatever you are having problems with.

The Top of My Radiator is Cold but the Bottom is Hot
When air gets into the heating system it bubbles through the pipes into the top of the radiator. It needs ‘bleeding’, which is a simple job. Click here to find out how to bleed a radiator in our Projects section.

The Top of My Radiator is Hot but the Bottom is Cold
Over time rust, scale and other impurities can build up in the bottom of the radiator preventing the water from properly conducting heat. This is a slightly bigger job than bleeding radiators, but it is still a job that can be tackled quite easily. Go to our Project on Removing a Radiator for instructions. You will need to know about Draining Down the system. Once you have drained down the system then you can remove the radiator and flush it out. When you refill the system you can add in a proprietary scale inhibitor, to help prevent this happening again.

This problem can also cause this next symptom

None of my radiators are getting very warm
See the top of the radiator is hot above. You will need to remove each radiator in turn and flush the system before refilling using a scale inhibitor.

The Radiators are Hot Downstairs but Cold Upstairs
This can show that the feed and expansion tank in your loft has run dry. The most likely cause is the valve in the feed and expansion tank (1), and needs to be sorted out quickly to prevent damage to the system. Changing the valve is within the capability of most Home Improvers.

For an explanation and diagram of a central heating system which includes a feed and expansion tank click on this image.

The Radiators are Cold Downstairs but Hot Upstairs
The most likely cause of this is a faulty central heating pump, which can be easily checked by a heating engineer.

My radiators are hot in some rooms and not in others
Check to see if it is the radiators nearest the boiler that are the hottest, if so your system needs balancing. For information on how to do this go to How to Balance your Central Heating System.