Why Is My Boiler Working for Hot Water but Not for Heating?
If your boiler is producing hot water but failing to heat your home, you are not alone - this is a common issue many homeowners face.
Several problems could be causing this, ranging from simple fixes to more serious system failures.
At Assett Plumbing, we’re here to help you diagnose the issue and provide fast, professional repairs across Northampton, Kettering, Corby and all the surrounding areas across Northamptonshire.
Common Causes of Hot Water but No Heating
Faulty Thermostat
Your thermostat controls how your heating system operates. If it's not working properly, your radiators may stay cold even if the boiler is running.
The first thing to do is check that your thermostat is set to the correct temperature. If your thermostat is battery-powered, replace the batteries and then try adjusting the settings or resetting the thermostat. If the thermostat still isn’t responding then it may need replacing.
Diverter Valve Issues
The diverter valve is responsible for directing hot water to either your taps or radiators. If it’s stuck or faulty, it may only be supplying hot water to your taps and ignoring your heating system.
Unfortunately, this cannot be fixed yourself, you’ll need a Gas Safe engineer to inspect and replace the valve if necessary.
Airlocks or Trapped Air in the System
Trapped air can prevent hot water from circulating through your radiators, leaving them cold.
Bleeding your radiators using a radiator key can release trapped air. If water starts coming out, close the valve. We have written detailed instructions on
how to bleed a radiator on our blog previously.
Low Boiler Pressure
Boilers require a certain level of water pressure to function properly. If the pressure drops too low, your heating may stop working. The first thing to do is check your boiler’s pressure gauge (usually found on the front). If it’s below 1 bar, this could be the issue. Top up the pressure using the filling loop (follow your boiler’s manual or call Assett Plumbing for guidance). If pressure keeps dropping, there may be a leak that needs professional repair.
Broken Pump
The circulating pump pushes hot water around your heating system. If it’s faulty, water won’t reach your radiators, even if your boiler is producing heat. You need to listen for unusual noises from the boiler—grinding or banging sounds could indicate a failing pump. Unfortunately, a broken pump usually requires professional replacement, which Assett Plumbing will be happy to help with.
When to Call Assett Plumbing
If you’ve checked the thermostat, bled the radiators, and ensured proper pressure but still have no heating, or you just need a friendly voice to offer some additional plumbing advice, it’s time to call the experts.
Assett Plumbing can help repair your heating issues quickly and efficiently. Call us today on 01604 372395.
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