When your underfloor heating stops working, it’s natural to panic — especially in the middle of a cold London morning. But before you reach for the phone, there are a few simple checks you can do yourself that could save you both time and money.
These quick, five-minute checks won’t require special tools or technical know-how. In some cases, they might even get your system running again without the need for a service call. And if you do end up calling an engineer, you’ll be able to provide them with helpful information that could speed up the repair.
Why These Checks Matter
Underfloor heating systems — whether electric or water-based — rely on a combination of power, controls, and clear heat flow to work efficiently. Sometimes, a small setting change or an overlooked detail can cause the system to shut down.
By taking a few minutes to investigate, you might discover:
- A tripped circuit breaker
- An incorrect thermostat setting
- Something blocking heat from reaching your room
Fixing these small issues yourself can restore heat instantly. If not, you’ll at least be able to tell your engineer exactly what you’ve already checked.
Check 1: Your Thermostat Settings
The thermostat is the control hub for your underfloor heating. If it’s not set correctly, your heating might not switch on at all — or it may turn off too soon.
What to do:
- Check the temperature setting – Make sure it’s set higher than the current room temperature. If the room is 18°C and your thermostat is set to 17°C, it won’t call for heat.
- Look at the schedule – Many thermostats run on timers. Ensure the heating is scheduled to be on at the current time.
- Inspect the display – If it’s blank, replace the batteries (for battery-powered thermostats) or check that it’s receiving power.
- Test a manual override – Temporarily set the thermostat to a high temperature to see if the heating kicks in.
London tip: Many retrofitted underfloor heating systems in London flats use wireless thermostats. These can lose connection if batteries are low or if the receiver is blocked by furniture.
Check 2: Your Power Supply
A sudden loss of electricity to your underfloor heating system is a common cause of failure.
What to do:
- Visit your fuse box – Look for any tripped switches. If your underfloor heating has its own circuit, reset it and see if the heating restarts.
- Check RCDs – If your system has a Residual Current Device, make sure it hasn’t tripped.
- Reset if needed – If you reset a breaker and it trips again immediately, stop and call an engineer — there could be a fault in the wiring or heating elements.
Safety note: Never attempt to open up electrical panels or wiring yourself. Only check visible switches and breakers.
Check 3: Boiler Pressure (for Wet Systems)
If you have a water-based underfloor heating system connected to your boiler, low water pressure can prevent it from operating.
What to do:
- Locate your boiler’s pressure gauge – This is usually on the front panel.
- Check the reading – Most systems require pressure between 1 and 1.5 bar.
- Top up if low – If the pressure is below this, you may be able to top it up yourself using the filling loop (follow your boiler manual for instructions).
London tip: In some older properties, shared boiler systems can make pressure maintenance trickier. If you’re unsure whether you have your own boiler or a communal one, check with your building management.
Check 4: Heat Flow Obstructions
Even if your underfloor heating is working, thick coverings can prevent warmth from reaching the room. This can cause your system to overheat locally and shut down as a safety precaution.
What to do:
- Look for rugs, mats, or thick carpets placed on the heated floor area.
- Move heavy furniture away from heated zones if possible.
- Allow airflow – The more the heat can circulate, the better the system will perform.
Pro tip: If you’ve recently redecorated or moved furniture, try moving these items and see if the heating resumes normal operation.
Check 5: Air in the System (for Wet Systems)
Water-based underfloor heating relies on a steady flow of hot water. Air bubbles can block this flow, causing uneven heating or a complete shutdown.
What to do:
- Feel the floor – Are some areas warm and others cold? This could indicate trapped air.
- Check the manifold – If you have access to your underfloor heating manifold, you may be able to see indicators of airlocks.
- Bleed the system – If you know how, bleeding the circuit can help. If not, make a note of the cold areas and share this with your engineer.
Extra: Look for Recent Changes
If your heating was working fine until recently, think about what’s changed:
- Have you had building work done? Floor tiling or drilling could have damaged cables or pipes.
- Have you replaced flooring? Some floor materials insulate more than others.
- Has your boiler been serviced or repaired? Settings may have been altered.
Making a note of these changes will help your engineer diagnose the problem faster.
When to Stop DIY and Call a Professional
While these quick checks are safe and simple, there are situations where you should stop and get professional help immediately:
- The fuse trips repeatedly when you turn on the heating
- You see water leaks, damp patches, or hear dripping
- You smell burning or notice scorch marks near the thermostat
- The thermostat or boiler display shows an error code you don’t understand
Why it matters:
Underfloor heating systems are complex. Attempting DIY repairs without training can make the problem worse or void your warranty. In London, most professional engineers carry diagnostic tools like thermal imaging cameras that can pinpoint faults without lifting your flooring.
Why These Checks Are Especially Useful in London Homes
London’s housing mix includes everything from Victorian terraces to modern flats, which means underfloor heating installations vary widely. In some older homes, wiring and boilers may already be under strain, so small issues can cause bigger disruptions. In newer apartments, communal heating systems can add another layer of complexity.
Doing these five-minute checks first helps you determine whether the problem is in your own system or part of a wider building issue — saving time if you need to contact your property manager.
Prevent Future Problems
To keep your underfloor heating running smoothly year-round:
- Book annual servicing for both your heating system and boiler
- Check thermostat batteries before the cold season starts
- Keep heated areas clear of heavy, insulating coverings
- Monitor pressure regularly on wet systems
- Act quickly if you notice cold spots or unusual noises
Final Thoughts
Underfloor heating is one of the most comfortable ways to warm your home — but like any heating system, it can develop faults. These five-minute checks can often get you back up and running without the need for a service call, or at least help you provide your engineer with useful details. If the issue persists, it’s time to call the professionals.