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Electric Underfloor Heating Not Working
Your electric underfloor heating has stopped warming the floor or will not switch on.
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What's happening?
Electric underfloor heating uses either heating cables or mat systems embedded in or under the floor to provide warmth. When it stops working, the floor remains cold. These systems are common in bathrooms, kitchens, and conservatories in UK homes. Faults can be in the heating element, the thermostat, or the electrical supply.
What usually causes it?
- Faulty thermostat or floor sensor
- Damaged heating cable — often caused by drilling or nailing into the floor
- Tripped MCB or RCD on the underfloor heating circuit
- Faulty relay or contactor in the thermostat
- Loose wiring connection at the thermostat or junction box
- Failed heating cable due to age or manufacturing defect
Is it dangerous?
Electric underfloor heating that is not working is not dangerous. However, if the circuit trips when you turn it on, there may be a damaged cable creating an earth fault. Do not keep resetting the circuit — call an electrician.
Can I fix it myself?
Check the thermostat settings and make sure it is calling for heat. Check the consumer unit for a tripped MCB. Some thermostats have a built-in diagnostics screen that shows error codes — check the manual. If the thermostat display is blank, check the fuse in the spur feeding it.
When should you call an electrician?
Call an electrician if the thermostat seems fine but the floor is cold, if the circuit trips when the heating turns on, if the thermostat shows an error code for the floor sensor, or if the heating stopped working after any building or flooring work.
What will the electrician actually do?
- Test the thermostat and floor temperature sensor
- Measure the resistance of the heating cable to check for breaks or damage
- Inspect wiring connections at the thermostat and junction box
- Use thermal imaging to identify cold spots indicating cable damage
- Locate and repair cable breaks if accessible
- Replace the thermostat or floor sensor if faulty
What will it cost to fix?
£100–£350
Thermostat and sensor replacements are at the lower end. Locating and repairing a damaged cable under tiles can be significantly more expensive due to floor access.
Find an electricianFrequently asked questions
We’re happy to answer all your questions.
Why has my underfloor heating stopped working?
The most common causes are a faulty thermostat or floor sensor, a damaged heating cable, or a tripped circuit breaker. An electrician can test the cable resistance to quickly determine if the cable is intact.
Can a damaged underfloor heating cable be repaired?
Yes, in many cases a break can be located and repaired with a specialist joint kit. However, this requires lifting the floor covering to access the cable at the point of damage.
How long does electric underfloor heating last?
Quality electric underfloor heating systems are designed to last 25-30 years or more. Most failures are caused by physical damage during building work rather than natural wear.
Could it just be the thermostat?
Yes, and this is the cheapest fix. A faulty thermostat or floor sensor can be replaced without disturbing the floor. An electrician can test these components quickly.
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