What to do if your radiators aren’t working

Finding that your radiators aren’t heating up even though your boiler is working as it should could leave you stumped as well as cold. If your boiler is the source of the hot-water that fuels your radiators, why is the central heating not working? There are a number of reasons why this could be happening, some simple some complex. Read on to find out what they are and how they could be fixed.


Get a service & repair quote 


What could cause this?

Radiator not heating up? We advise that you firstly check ALL of the radiators in your home, as if any radiator is heated even slightly, you could assume that your boiler is working fine.

Below are some of the typical causes of radiators not heating up despite there being no clear issue with your boiler. For health and safety reasons, we recommend seeking the advice of a qualified engineer.


1. Central heating controls – Radiator issues could be due to there being incorrect settings on your heating controls. If this is the case, you may be able to rectify this problem yourself. Make sure that your central heating is turned on and also check the thermostat to ensure that it is turned up properly; additionally, you could check that the timer’s settings are accurate. If a power cut or seasonal time change has recently occurred, your timer may have incorrect settings and may be the cause of your problem.


2. Air pockets in the radiators Air can often get trapped in your central heating system and cause faults such as cold spots. This is another issue that you may be able to fix yourself by bleeding your radiators. In order to do this, follow these simple steps:

a. First ensure that your heating is turned off and your radiators have completely cooled

b. Fit your radiator key into the valve which is located at the top of your radiator and twist the key slowly; be sure to use a rag/cloth to protect your hands and to catch any drips of water that may come out amidst the trapped air being released.

c. Once the air has been released, you should quickly refit the valve to prevent water from escaping.

Here’s a video to provide you with extra guidance:

Get a service & repair quote 


3. Sludge, debris or blockages in your radiators Substances such as dirt and sludge can accumulate in your central heating system over time and cause blockages that could hinder the quality of your heating. To deal with this issue, we recommend getting a system Powerflush done by a qualified engineer. A Powerflush involves the use of a specialised machine to send a chemically infused liquid through your system at a high velocity to rid your central heating of any inhibiting substances.

Powerflushing is one of the many domestic heating services that we offer at HomeServe, so if you feel that your home heating could benefit from a system Powerflush, get in touch to arrange an appointment with one of our Gas Safe registered engineers.


4. Low boiler pressure Low pressure could also be a potential cause of your radiator issue. To check this, you could take a look at your system’s pressure gauge, if your boiler pressure is too low (below 1) you could consider repressurising the boiler. This is fairly easy and usually doesn’t require engineer assistance. If comfortable, you could attempt to do this yourself by simply following these steps:

a. Ensure that your boiler is switched off and that the system is cool

b. Locate your filling loop; this is a flexible hose with a valve at each end (typically silver or grey in colour). Ensure that both ends of the hose are securely attached to both valves.

c. Open the valves either by tap handles or using a flat-headed screwdriver, to allow the cold mains water into the system; you should be able to hear the sound of the water filling the system.

d. Monitor the pressure gauge and close both valves once the pressure has reached 1.5.

e. Once the right pressure has been reached, switch the boiler back on.


5. An issue with the motorised diverter valve If none of the above seem to be the cause of your radiators not heating up, there could be a fault with your motorised diverter valve. At times, your boiler’s diverter valve could become jammed and stuck on heating mode, which could hinder your system’s ability to deliver hot water. This is NOT an issue that you should attempt to fix yourself; we recommend you seek the help of a qualified, Gas Safe engineer who could come and replace the valve or service its working parts.


Our highly trained Gas Safe registered engineers are more than capable of rectifying issues such as radiator faults. So, whatever the cause may be for your radiators not heating up, our experts will aim to provide you with an effective solution to get your home heating up and running smoothly again. Contact us today to arrange an appointment, we’ll aim to send an expert to your home at a time to suit you.


Get a service & repair quote 


The above information has been provided by HomeServe and is for information purposes only. It is not a substitute for a qualified engineer’s assessment, survey or advice. Electric or fuel appliances may pose a significant risk to health and safety where a person is not suitably qualified to undertake such an installation or repair. Boiler repairs should by law always be carried out by a qualified and Gas Safe engineer, so you should never attempt to carry out any repair work on your boiler yourself.

Information and other materials on this website are not intended to constitute professional advice and should not be relied upon. Please see our Terms of Use for further details.

Related articles

How to bleed a radiator

How to bleed a radiator

Bleeding a radiator is an easy and cheap fix for combatting cold and patchy radiators. It's something anyone can do in their own home without...
9 common boiler faults & problems

9 common boiler faults & problems

The average homeowner doesn’t necessarily need to know what’s going on beneath the surface of a central heating system, but they do need to regularly...
5 Energy saving tips to make the most out of your central heating

5 Energy saving tips to make the most out of your central heating

While the lifespan of the average boiler is 12 years, it’s important to maintain it regularly to ensure maximum longevity. If your boiler and central...

Get a Boiler Quote

Need a new boiler? Get a boiler quote online in 60 seconds.

Get a boiler quote