Quick Checks When Underfloor Heating Stops Working
Before calling an engineer, try these simple checks that may resolve your underfloor heating problems
1. Check the Thermostat
- • Ensure the thermostat is set higher than current room temperature
- • Check batteries in wireless thermostats
- • Verify the timer/schedule is correctly programmed
- • Try switching to manual override mode
Need help? See our thermostat repair service
2. Check Power Supply
- • Check if the circuit breaker has tripped
- • Verify the isolation switch is turned on
- • Look for any visible damage to wiring
- • Test the socket/power source with another device
For electrical faults, see electric UFH fault guide
3. Check the Boiler (Wet Systems)
- • Ensure your boiler is running and producing hot water
- • Check boiler pressure (should be 1-1.5 bar)
- • Verify the heating is enabled on the boiler
- • Look for error codes on the boiler display
For wet system issues, see wet UFH repairs
4. Check Zone Valves & Manifold
- • Check if zone valves are open (listen for actuator click)
- • Feel the manifold pipes - they should be warm
- • Verify flow meters show water movement
- • Check for trapped air in the system
Need repairs? See zone valve repairs or manifold repairs
Why Is My Underfloor Heating Not Working?
Electric System Issues
Heating Cable Break
Damage to the heating cable from floor work, furniture installation, or wear can cause partial or complete failure.
Learn about electric UFH faults →Faulty Thermostat
The thermostat may have failed or lost communication with the heating system.
Thermostat repair service →Tripped RCD/Circuit Breaker
Electrical faults or moisture ingress can trip safety devices, cutting power to the system.
Wet System Issues
Pump Failure
The circulation pump may have seized or failed, preventing hot water from flowing through the pipes.
Pump repair service →Air Locks
Trapped air in the system prevents water circulation, causing cold spots or complete failure.
Air lock removal service →Leaks in the System
Water leaks cause pressure drops, preventing the system from operating correctly.
Leak detection service →Common symptoms and what they mean
Underfloor heating stopped working
A system that worked last winter and now does nothing usually has a failed pump, a tripped fused spur, a flat thermostat battery or a wiring centre relay that has stuck. Check power and thermostat display first, then the pump for heat and vibration.
Underfloor heating cold across the whole floor
If every room is cold but the boiler fires, the water is not reaching the loops: a closed blending valve, an airlocked manifold, a seized pump or low system pressure. All four are quick to test with the manifold cover off.
One underfloor heating zone not working
A single cold room points to that zone's actuator, flow meter or thermostat rather than the whole system. Feel the flow and return pipes for that circuit at the manifold — if both are cold while others are warm, the actuator is not opening.
Manifold-related causes
Leaking unions, clouded or seized flow meters, failed actuators, a stuck mixing valve and loose wiring centre terminals are the most common reasons a floor underperforms. These component faults are all covered on our underfloor heating manifold repair page.
When to Call a Professional
Call an engineer if:
- The system is completely cold and basic checks haven't resolved the issue
- You notice water leaks, damp patches, or unexplained pressure drops
- Circuit breakers keep tripping when heating is enabled
- Only some rooms/zones are heating while others remain cold
- The system is making unusual noises (gurgling, banging)
Need an engineer?
If this guide points to a fault you would rather not tackle yourself, our REFCOM-registered, F-Gas certified engineers cover London and the M25 with 24/7 emergency callout. Engineer time is £120 + VAT per hour with a written quote before any chargeable parts are fitted. Start with the relevant service below, or contact us for a site survey.