This is a surprisingly common issue in many homes, and it can be frustrating—especially on a chilly morning when the house feels like an icebox, but your taps are giving you perfectly hot water! In this blog, we’ll break down the possible reasons why this happens, explain things in simple terms, and help you understand what you can check yourself before calling out a heating engineer. Let’s dive in! Understanding.
How Your Boiler Works
First, it helps to know the basics of how a boiler works. In most UK homes, a boiler provides both hot water for your taps and showers and central heating for your radiators.
When you turn on the heating, the boiler warms up water, which is then pumped through the radiators to heat up your home. So, when you’re getting hot water but no heating, it means your boiler is working partially. That’s good news—it’s not completely dead. But it’s also a clear sign something’s not right with the heating side of the system.
Common Reasons Why You Have Hot Water but No Heating
1. It tells the boiler when to fire up the heating. If the thermostat isn’t working properly, your boiler might never get the message to start heating your radiators.
What to check: Make sure the thermostat is turned on.
Check the temperature setting—sometimes it’s set too low, especially after a power cut. Replace the batteries if it’s wireless.
2. If the pressure drops too low, the boiler may still give you hot water, but the central heating won’t work properly because it can’t push hot water around the system. What to check: Look at the pressure gauge on your boiler. If it’s below 1 bar, it likely needs topping up. You can usually do this yourself using the filling loop, but check your boiler manual.
3. The Heating Is Turned Off on the Controls This one sounds obvious, but it’s surprisingly common! Some boilers have separate settings for hot water and heating. You might have accidentally turned the heating off at the boiler or on your control panel. What to check: Look at the boiler’s display or control panel. Make sure the heating is switched on.Check the timer or programmer settings—sometimes it’s set to come on only at certain times of the day.
4. Air in the Radiators If your boiler is working but the radiators stay cold, the problem may not be the boiler itself, but air trapped inside the radiators. Air prevents hot water from circulating properly, leaving you with cold radiators and a warm boiler.
What to do: Check if the top of your radiators is cold while the bottom is warm. Use a radiator key to release the air.
5. Faulty Diverter Valve The diverter valve is a key part inside combination boilers. It directs hot water to either your taps or your heating system. If the valve is stuck in the “hot water” position, you’ll get lovely hot showers but no heating.
Signs of a faulty diverter valve:
Hot water works perfectly, but the radiators stay cold. Sometimes you hear clunking or tapping noises from the boiler.
This is usually not something you can fix yourself—you’ll need a heating engineer.
6. Circulation Pump Problems The circulation pump pushes hot water from the boiler around your central heating system. If the pump fails, the boiler can heat the water, but it can’t move it to the radiators. Signs of pump issues: Boiler fires up, but no warmth reaches the radiators. You hear banging or rattling sounds. You notice some radiators heat up slightly but others stay cold. Again, this is a job for a professional.
When to Call a Professional
While you can check the thermostat, boiler settings, and pressure yourself, some problems—like a faulty pump or diverter valve—require a trained engineer.
Remember, safety first! Never take apart your boiler or try to fix internal parts yourself. Preventing Heating Problems in the Future The best way to avoid heating breakdowns is to keep your system well-maintained: Annual boiler service: This can catch problems early before they turn into bigger (and more expensive) issues. Bleed radiators regularly: Especially at the start of the heating season. Check boiler pressure: Get into the habit of checking every few weeks during winter. Keep an eye on your thermostat and controls: Make sure schedules and temperatures are set as you want.
