Read us to know the causes and solutions for when radiators stay cold

My radiator is cold and not working, how do I fix it?

While cold radiators could be a result of a more serious problem with your central heating system or boiler, there are a number of smaller faults that should be ruled out first.


The thermostat’s set too low


Check that the thermostats in your rooms and on the boiler are set correctly. Your manufacturer's manual will provide details on the correct settings.


The timer or programmer isn’t working


Check that the timer or programmer is switched on and set correctly. Your manufacturer's manual will provide details on the correct settings.


The gas boiler's pilot light’s out


If you find that the gas boiler’s pilot light has gone out consult the relighting instructions that can usually be found printed on the back of the boiler’s front panel.


There’s a build-up of rust and sludge


If you suspect that there’s been a build-up of rust or sludge in your radiators there are two ways to remove it, depending on the type of system you have:


  • For open-vent systems

For heating systems that are conventional, un-pressurised and tank fed, you can use a heating system sludge remover.

Available from most DIY stores, simply add the liquid to the feed and expansion tank and, after a few days, empty and refill the system.


  • For non-open vent systems

If you don't have an open vent system, you'll need to flush your radiators with a hosepipe. Your manufacturer's manual will provide further information on how to do this correctly.


There are air pockets in the system 


To remove any air that’s become trapped within your central heating system, bleed your radiators.

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