If you’ve found yourself asking, “Why is my central heating not working?”, you’re definitely not the only one. We get this exact question from customers every day, and usually at the worst possible time cold nights, early mornings, or right when the temperature drops. Central heating systems are fantastic when they work, but the moment something goes wrong, the whole house can feel uncomfortable. And the frustrating part? The cause isn’t always obvious.
Because we deal with heating issues constantly, we’ve seen the same faults happen again and again. Below, we break down the most common reasons for central heating failure, why those issues happen, what you can safely check yourself, and when you should call an engineer to take over.
Low Boiler Pressure
Low boiler pressure is by far the most common reason a heating system stops working. When the pressure drops, the boiler can’t push hot water around your radiators, so the heating simply doesn’t come on.
You might notice:
The boiler pressure gauge sitting under 1 bar
Your heating not coming on at all
Fault codes such as F22, E119, or similar
Hot water that works but radiators that stay cold
The pressure can drop because you’ve bled your radiators recently, there’s a small leak somewhere, or the boiler has a worn component. You can re-pressurise the boiler yourself using the filling loop, ideally bringing it up to around 1.2–1.5 bar. But if the pressure keeps falling, that’s when you need us constant pressure loss usually means there’s an underlying fault that needs professional attention.
Thermostat Issues Stopping the Heating from Kicking In
You’d be surprised how many heating problems come down to a faulty or confused thermostat. If the thermostat isn’t calling for heat, the boiler won’t fire, no matter how cold your home gets.
Common thermostat issues include:
Dead batteries
The temperature set too low
Incorrect schedules
The device placed in a bad location
A faulty or outdated unit
Before calling for help, try increasing the temperature, replacing the batteries, or checking the heating schedule. If nothing changes, the thermostat may need repairing or replacing. We install modern smart thermostats for many customers, giving them far better control over their heating.
Air Trapped in the Radiators
Air in the system is another very common issue, especially after long periods of not using the heating. When radiators feel warm at the bottom but cold at the top, trapped air is almost always the cause.
You might notice:
Gurgling noises
Uneven heating in different rooms
Radiators that never fully warm up
Bleeding the radiators usually solves the problem, and it’s something most homeowners can do themselves. However, if the issue keeps coming back, it could mean the boiler is losing pressure or the system is full of sludge. In those cases, we can diagnose the cause properly and restore your heating to full performance.
Faulty Central Heating Pump
The pump’s job is to move hot water around your system. When it fails, the water doesn’t circulate properly, leaving your radiators lukewarm or completely cold.
Signs of a failing pump include:
Slow-to-warm radiators
Hot water upstairs but not downstairs
Boiler constantly cycling on and off
New humming or grinding noises
Pumps can fail due to age, electrical issues, or sludge buildup. This isn’t a DIY job pump repairs and replacements should always be handled by a qualified engineer.
Frozen Condensate Pipe During Cold Weather
This is a classic winter problem. If the condensate pipe outside your home freezes, the boiler shuts down to protect itself.
Typical signs include:
Strange gurgling sounds
A fault code on the boiler display
The boiler trying to fire but failing repeatedly
You can defrost the pipe yourself by pouring warm (not boiling) water over it and then resetting the boiler. If freezing becomes a regular issue, we can insulate or reroute the pipe to prevent future problems.
Sludge Buildup Inside the System
Over time, rust, limescale, and debris build up inside central heating systems, forming thick sludge that blocks the flow of water. This affects performance and makes the system work harder.
Common signs include:
Radiators cold at the bottom
Patchy heat or slow response
Noisy boiler
Higher energy bills
A professional power flush or chemical flush will clear the sludge and help the system run properly again.
What You Can Do Before Calling an Engineer
Before you book a repair, it’s worth checking a few simple things.
Make sure your boiler has enough pressure, your thermostat is set correctly, the system clock hasn’t reset itself, and your radiators are fully bled.
These small checks can sometimes bring your heating back to life without any further work. But if you’ve tried these and the heating still isn’t working properly, that’s your sign to call in a professional.
We Can Fix Your Central Heating Quickly
If you’re still wondering why your central heating isn’t working, we’re here to help. We repair heating systems every single day and can quickly identify what’s gone wrong, explain it clearly, and fix it properly.
Whether the issue is with the boiler, pump, radiators, pipework, thermostat, or the system as a whole, we have the experience and tools needed to get everything running smoothly again. Heating problems rarely fix themselves, and leaving them too long can lead to bigger breakdowns so if your system still isn’t working right, get in touch and we’ll get your home warm again as quickly as possible.
Call A Heating Engineer Now!
If your heating system still isn’t working after following these steps, it’s time to bring in an expert.
Reach out to us for qualified engineers and we’ll carry out a full inspection, identify the exact cause of the problem, and provide a reliable repair that keeps your system running safely and efficiently for the long term.