Underfloor heating not working is usually more than an inconvenience. In homes, rental properties, offices, care settings and commercial premises, a failed UFH system can leave rooms cold, disrupt occupancy, expose hidden leaks, and increase pressure on the boiler or heat source.
Fix & Repair Engineers provides professional underfloor heating fault diagnosis and repair support for wet and electric UFH systems. We investigate the system properly - thermostats, wiring centre, manifold, actuators, pump, flow rates, pressure behaviour, sensors and heat-source demand - so the cause is found rather than guessed.
Underfloor Heating Not Working: What It Usually Means
When underfloor heating stops working, the visible symptom is simple - cold floors or rooms that do not reach temperature. The actual cause can sit in several different parts of the system. That is why a proper diagnosis matters.
Wet underfloor heating depends on the boiler or heat pump, controls, manifold, pump, blending valve, actuators and water flow through individual pipe loops. Electric underfloor heating depends on power supply, thermostat demand, floor sensors, relay operation and the continuity of the heating mat or cable.
Wet & Electric UFH
Fault diagnosis for both water-based and electric underfloor heating systems
Controls & Zoning
Thermostats, wiring centres, actuators and room-by-room demand checked
Flow Diagnosis
Manifold, pump, air, balancing and circulation issues assessed methodically
Clear Advice
Written findings and repair recommendations provided after the visit
Common Signs Your Underfloor Heating Needs Repair
Most UFH faults show up in predictable ways. The pattern of the problem often tells an engineer whether the cause is likely to be local to one zone or affecting the whole system.
No Heat Anywhere
Often linked to the boiler or heat source, central controls, power supply, UFH pump, low pressure or manifold circulation.
One Room Not Heating
Usually points to a zone-specific issue such as a thermostat, actuator, valve pin, air lock or poor flow through one loop.
Patchy Warmth or Cold Spots
Can be caused by trapped air, flow imbalance, sludge, restrictions, poor commissioning or insulation and floor build-up issues.
System Pressure Drops
Repeated pressure loss may indicate a hidden leak, failing PRV, expansion vessel problem or another central heating fault.
Electric UFH Trips the RCD
Repeated electrical tripping can indicate cable damage, moisture ingress, insulation breakdown, thermostat failure or circuit faults.
Slow Warm-Up
UFH is naturally slower than radiators, but abnormal delay or failure to reach temperature needs investigation.
A useful rule is this: if the whole system is cold, think heat source, pump, power, pressure or controls. If only one room is cold, think thermostat, actuator, air or loop flow. If the problem is electrical or keeps tripping the RCD, stop resetting it and arrange professional testing.
Wet Underfloor Heating Not Working
Wet underfloor heating is a water-based system. It normally receives heat from a boiler, heat pump or other heat source and distributes warm water through loops connected to a manifold. Because several components must work together, the fault is not always where the symptom appears.
Common wet UFH faults we diagnose
Controls and Zone Faults
- Room thermostat not calling for heat
- Flat thermostat batteries or incorrect programme
- Wiring centre faults or no output to actuator
- Stuck or failed thermal actuator
- Valve pin seized after a long inactive period
- One zone staying cold while others heat normally
Hydraulic and Flow Faults
- UFH pump failed, seized or not energised
- Air trapped in loops or manifold
- Flow meters showing little or no movement
- Incorrectly balanced loops
- Blocked strainer, debris or sludge restriction
- Mixing valve or blending set fault
Electric Underfloor Heating Not Working
Electric underfloor heating faults need a different diagnostic approach. There is no manifold, pump or water pressure. The key checks relate to power, thermostat demand, floor temperature sensor operation, relay output, cable resistance and insulation condition.
| Symptom | Likely causes | What should happen next |
|---|---|---|
| Electric UFH not heating | Thermostat settings, no power, failed floor sensor, thermostat relay fault, broken heating cable or connection issue | Engineer/electrician checks safe supply, sensor readings, thermostat output and cable continuity/resistance |
| RCD keeps tripping | Insulation breakdown, moisture ingress, damaged cable, faulty thermostat or circuit issue | Stop repeated resets and arrange professional electrical testing |
| Floor overheats or underheats | Incorrect thermostat settings, failed floor sensor, poor sensor placement or control calibration issue | Controls and sensor readings should be tested before replacing components |
| Only part of the floor warms | Cable/mat damage, poor installation layout, floor covering issue or failed section | Electrical test results help confirm whether the heating element is intact |
Our Underfloor Heating Repair Process
Good UFH fault diagnosis follows the evidence. We avoid the common mistake of replacing parts at random. Instead, our engineers work through the system in a structured way, from the controls and heat source through to manifold operation, flow behaviour and electrical checks where required.
Fault Description and System Type
We confirm whether you have wet or electric UFH, which rooms are affected, when the fault started, and whether there are pressure drops, tripping electrics or boiler fault codes.
Controls and Demand Check
Thermostats, time schedules, wiring centres, zone signals and heat-source demand are checked to confirm whether the system is actually asking for heat.
Manifold, Pump and Flow Assessment
For wet UFH, we assess manifold valves, flow meters, actuators, pump operation, isolation valves, balancing and signs of air or restriction.
Repair Recommendation
Once the fault is identified, we explain the repair options clearly, whether that means replacing an actuator, resolving a pump issue, bleeding loops, repairing controls or arranging leak detection.
Where a specialist part is required, we will advise on availability, lead time and whether a temporary measure is appropriate. For commercial premises, landlords and property managers, written findings help support maintenance records and decision-making.
Pressure Loss, Leaks and Cold Spots in Underfloor Heating
Pressure loss should not be ignored. If the boiler pressure keeps dropping and your underfloor heating is not working properly, the fault may be outside the boiler itself. A leak on the heating circuit, a manifold issue, a pressure relief valve fault or expansion vessel problem can all cause repeated low-pressure symptoms.
Warning Signs of a Possible UFH Leak
- Boiler pressure repeatedly drops
- One UFH zone becomes colder than normal
- Damp patches, staining or floor movement appear
- You need to top up the system frequently
- Flow drops on a particular manifold loop
- Heating works briefly then fails again
Cold Spot and Flow Causes
- Air trapped in one or more loops
- Partially closed or stuck valves
- Actuator not opening fully
- Flow rates out of balance
- Sludge or debris restricting circulation
- Incorrect flow temperature or mixing-valve issue
Book Underfloor Heating Repair in London and the Home Counties
We help homeowners, landlords, letting agents, facilities managers and business owners resolve underfloor heating faults across London and the Home Counties. Whether the issue is a cold room, no heat throughout, pressure loss, electric UFH tripping or a suspected manifold fault, we can arrange a diagnostic visit.
Helpful Information When Booking
- Whether the system is wet or electric UFH
- Which rooms or zones are affected
- How long the fault has been present
- Any boiler fault codes or pressure changes
- Whether the RCD or breaker has tripped
- Photos of the manifold, thermostat or error messages if available
Service Areas
- London and Greater London
- Essex, Kent and Suffolk
- Hertfordshire and Buckinghamshire
- Surrey and Sussex
- Domestic and commercial premises
- Emergency bookings subject to engineer availability
