Underfloor heating not working can quickly turn a cosy day into a frustrating one, especially when temperatures drop. Whether you rely on electric or wet underfloor systems, any disruption can affect your entire home's comfort. In this guide, we'll break down common issues and how to troubleshoot them effectively.
If your heating feels patchy or has stopped altogether, our experienced team at Maintracts Services can help. We're trusted specialists in London for underfloor heating repairs, diagnostics, and long-term maintenance. Call us on 020 8682 2244 or email info@maintracts.co.uk for fast, expert assistance.
Maintracts Services helps restore your underfloor heating—fast, safe, and with minimal disruption.
Underfloor Heating Troubleshooting: Where To Begin
Diagnosing an underfloor heating issue starts with identifying whether you're dealing with a wet (water-based) or electric system. Both come with their own set of common problems.
Before you begin any troubleshooting, check the following:
- Is your thermostat set correctly?
- Has a circuit breaker tripped?
- Are other heating zones working properly?
These basics can help rule out simple issues and narrow down what's gone wrong.
Also Read: Is It Better To Have Underfloor Heating On All The Time?
Common Reasons Why Wet Underfloor Heating Is Not Working
1. Thermostat Control Issues
If your thermostat isn't turning on the system or displaying incorrect readings, it may be:
- Incorrectly programmed (especially after a power cut)
- Malfunctioning due to old age or wiring faults
- Not calibrated to the floor sensor
Try resetting the thermostat or replacing the batteries. Still no luck? A replacement may be required.
2. Electrical Faults In Heating Cables
Electric systems rely on heating mats or cables beneath your floor. A fault here might:
- Trigger the circuit breaker
- Cause only part of the floor to warm
- Be invisible without proper testing tools
Never attempt cable repairs yourself. Our engineers at Maintracts use thermal imaging and resistance testing to locate faults quickly.
3. Trapped Air In Pipes (Airlocks)
With wet underfloor heating, trapped air in pipes can cause cold patches or stop heat circulation entirely. This often happens after filling or draining the system.
Bleeding the system correctly can remove air pockets. We'll cover this later in our FAQs.
4. Faulty Heating Pump
A heating pump that has stopped working can't push warm water through the pipes. Signs include:
- No noise or vibration from the pump
- Cold pipes leading away from the manifold
- Error lights or temperature inconsistencies
You may also experience a pressure drop in UFH systems. This is a key sign that your pump or expansion vessel needs attention.
5. Mixing Valve Malfunction
The mixing valve blends hot water with cooler return water to prevent overheating. If it fails, your floor may:
- Stay cold
- Get too hot
- Heat unevenly in zones
Mixing valve problems often require replacement or recalibration.
6. UFH Actuator Issues
If some rooms are warm while others stay cold, check your actuators (located on the manifold):
- They control the heat in each room/zone
- A stuck actuator may block flow to a particular area
- Wiring issues can also stop them from opening
Our engineers can test and replace faulty actuators to restore balanced heating.
7. Heating Manifold Blockage
A heating manifold blockage restricts water flow and affects the entire zone. Look out for:
- Inconsistent temperatures
- Rattling noises
- Dirty or corroded valves
Routine flushing or a chemical clean may resolve the issue.
8. Uneven Floor Warmth Or Cold Spots
Uneven heat could stem from:
- Insufficient insulation beneath the floor
- Zone motorised valve faults
- Pipe layout design errors
Read more about heating design in our guide: Underfloor Heating Vs Radiators.
How To Know When To Call The Experts
Underfloor heating systems are complex, involving electrical and plumbing components. If you've:
- Checked the thermostat
- Bled the system
- Inspected obvious blockages or trip switches
And the problem persists; it's time for a professional diagnosis.
Our engineers at Maintracts Services are trained to repair electrical and wet systems, detect hidden faults, and restore comfort efficiently. Curious about how your system operates?
Also Read: How Does Underfloor Heating Work?
FAQs: Underfloor Heating Issues In London
Why is my underfloor heating not turning on?
Check the thermostat, circuit breaker, and pump. If these are working, it could be a deeper issue with the wiring or heating element.
What to do if some areas are cold but others are warm?
This could mean an actuator is stuck, or there's air trapped in a pipe serving that zone. A system check can reveal which one.
How do I bleed air from my UFH pipework?
Use the bleed valves located on the manifold. Open them carefully to release trapped air. Always consult a heating engineer if unsure.
Could a faulty pump stop my wet underfloor heating?
Yes, without a working pump, water won't circulate, resulting in no heat. You might also hear no humming sound or feel no warmth at the manifold.
How do I fix a stuck actuator on the manifold?
You can try gently pressing the actuator pin. If that fails, a replacement may be needed.
Can a broken mixing valve cause overheating or cold floors?
Absolutely. A failed mixing valve can send either too little or too much hot water to the floor zones.
Why is the thermostat not controlling my underfloor heating properly?
It could be a wiring issue, a battery failure, or a misconfigured programme. Replacing or resetting it often solves the issue.
How do I check for low pressure in a wet UFH system?
Most manifolds have a pressure gauge. If it's below 1 bar, you likely have a pressure drop that needs topping up.
What electrical faults could affect electric underfloor heating?
Damaged cables, faulty thermostats, or tripped circuit breakers can all disrupt power to your system.
When should I call a professional plumber or electrician?
If bleeding, resetting, and thermostat checks don't solve the issue, call us at Maintracts for a proper assessment.
Get Reliable Heating Repairs With Maintracts Services
Don't let underfloor heating problems leave your home feeling cold. At Maintracts Services, we offer expert diagnostics, repairs, and maintenance for both wet and electric systems across London. With over 40 years of experience, our team handles everything from pump faults and mixing valve issues to full thermostat control replacement.
We work with precision and speed, minimising disruption and restoring warmth to your property as quickly as possible. Need urgent help or a quote? Call us on 020 8682 2244 or email info@maintracts.co.uk today to book an expert inspection.