Why is my hot water working but not my heating?

You’ll be relieved to know, there’s usually a straightforward reason why your hot water is working but your heating is not. You’ll need to check these three things:

1. Check the settings

There are some key things to check on your boiler’s control panel:

• Is it set to ‘hot water only’? Homeowners often make this selection during the summer
• Is the timer set correctly? Make sure the day, time, and duration are correct – often a problem after daylight saving
• Is your boiler pressure too low? Boiler pressure should be between 1 and 2 bars when the heating is on. Check the pressure gauge on your boiler, your manual for the recommended pressure for your model, and how to repressurise it (if needed)

2. Check your thermostat

• Is the thermostat set too low? Aim for between 18-21C to heat your home to a comfortable temperature
• Are the batteries working? Usually indicated by a low battery light, check whether this could be the issue
• Is it wireless? Make sure it’s in a central position in your home with a balanced surrounding temperature

3. Check your radiators

• Do you have thermostatic radiator valves? Check each one is set to the correct temperature
• Are they lukewarm or cool in certain areas? Your radiators might need bleeding to release air or cleaning to remove sludge

Hot water working but the heating isn’t – possible boiler faults

If you’ve run through the troubleshooting tips above to work out why your hot water is working but your heating isn’t, it might be an issue within the boiler.

There are three common reasons why you’re getting hot water but no heating – none of which should be tackled unless you’re a qualified Gas Safe registered engineer:

• Diverter valve – your combi boiler has a diverter valve to direct hot water to either your rads or taps and showers. This valve does have a lifespan and might need replacing, or it may just be stuck or faulty
• Blocked burner – your boiler’s burner can get congested with carbon build-up and may need cleaning and reinstalling
• Ignition lead needs replacing – the ignition lead within your boiler also has a lifespan and may need replacing

Need the services of a local expert to get your heating working again? Use our directory to find a certified Gas Safe Engineer to help.