Updated on 3rd August, 2023 by Martin Astley
Do you have hot water but no central heating? If your boiler seems to be working and your hot water supply is still functioning, but your central heating is not working, then the problem is either down to the settings on your boiler and central heating system or because a component of the boiler – almost certainly the motorised diverter valve – is broken.
If you cannot get your central heating back on by adjusting the settings, then you will likely need to replace the valve; we would not advise you to do so unless you are an experienced professional engineer.
If you’re experiencing central heating problems, first check all the radiators in your house to check that none of them are working. If just one radiator feels slightly warm, then there is nothing wrong with your boiler.
If one of your radiators is mildly warm, try bleeding your radiators; just turn the bleed valve on the side of the radiator in an anti-clockwise direction with a radiator bleed key. Put some pans and towels underneath the radiator and the bleed valve to prevent dirty water from dripping on your floor.
Alternatively, radiators that are cold at the sides and bottom but are warm on the top are likely full of sludge. To repair this problem, read our advice about cleaning a radiator.
If you still haven’t been able to resolve the problem but think that it is due to your radiators, read ‘My radiator is cold – help!‘ for more information.
Central Heating Settings
Are you sure that your central heating is switched on? Check that the thermostat on your boiler (or elsewhere in the house) is turned up properly and that the timers are set correctly. If there has been a power cut, your boiler may have reset and you will need to adjust the settings again. If the clocks have recently gone forwards or back, then your timer may be set incorrectly and will need to be adjusted.
Is the pressure on your boiler at one bar? If the water pressure is too low, then your central heating may not work as well as it should. If the pressure is below one bar, then repressurise your boiler – you may have to refer to your user manual.
Try resetting your boiler – there may be a customer-operated reset button or switch on the outside of the appliance, probably on the front. Do not remove the boiler cover or any casing to access this button. Alternatively, turn the electric power to your boiler off, wait 30 seconds, and then turn it on again.
Broken Diverter Valves
If you have tried all the above repairs but your central heating is still not working, then you may have a broken diverter valve. These valves switch heat between your water supply and your central heating. After prolonged use, a range of faults can develop in these valves, which prevent them from changing position; therefore, either your central heating or your hot water will stop working.
Only experienced professionals should repair boilers. The cost of these repairs can be very high – call out charges, parts and labour can make a boiler repair an expensive experience!
Still, Having Trouble?
Don’t attempt to touch any part of your boiler or central heating system if you’re unsure. Did you know? It’s illegal for anyone to use a gas appliance if they think it’s unsafe. It’s always better to be safe than sorry as you could make things worse.
Instead, call us on 0345 3192 247 and we can help. Our technical team will run through some simple troubleshooting to see if your problem can be resolved on the phone or they can book one of our friendly and knowledgeable Gas Safe registered engineers to get you back up and running as soon as possible.
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