Underfloor Heating Controls

How Electric Underfloor Heating Works

Electric underfloor heating uses a resistive heating element (mat or cable) laid beneath the floor surface. The element is wired to a thermostat which switches it on and off to maintain the setpoint temperature.

Components:

• Heating element: Mat or cable, installed by a flooring contractor or electrician — rated in W/m²
• Thermostat: Controls the element based on floor or air temperature
• Dedicated circuit: A dedicated RCBO circuit from the consumer unit (sized for the element's total wattage)
• Floor temperature sensor: A probe sensor laid in the screed/adhesive near the element — prevents overheating and provides accurate floor temperature control

Thermostat Types

Wilsons' typical install: Heatmiser neoStat or Warmup 4iE — gives the customer app control and energy monitoring.

Survey

Before installing thermostats on an existing UFH system:

1. Test the element: Measure element resistance with a multimeter — if open or incorrectly high resistance, the element is damaged and must be replaced before the thermostat is fitted.
2. Confirm element wattage: The thermostat must be rated for the element's load (typically 16A — check thermostat spec).
3. Check floor probe: Confirm the probe sensor wire is in place and accessible at the thermostat back box.
4. Check the circuit: Confirm the UFH circuit is on a dedicated RCBO, sized for the element's load.

Installation Procedure

Step 1 — Isolate

Isolate the UFH circuit at the consumer unit. Prove dead at the thermostat back box.

Step 2 — Check element resistance

Using a multimeter:

• Measure resistance between the two element conductors (should match manufacturer's spec — typically 20–200Ω)
• Measure insulation resistance between each conductor and earth — should be above 1MΩ
• Record the readings

Step 3 — Connect the thermostat

Standard thermostat terminals (always refer to manufacturer's wiring diagram):

Fit the thermostat in the back box and fix the faceplate.

Step 4 — Fit the floor probe (new installations)

On new installations before the floor is laid:

• Lay the probe sensor wire along the heating element, between cable runs, approximately 200–300mm from the wall
• Route the probe wire back to the thermostat back box in conduit
• Leave sufficient spare wire in the back box to allow the thermostat to be removed without disturbing the floor

Step 5 — Commission

1. Restore power
2. Configure the thermostat (temperature setpoint, schedule, sensor mode — floor or air)
3. For smart thermostats: connect to the customer's Wi-Fi and configure the app
4. Test: set the thermostat above the current floor temperature and confirm the element switches on — check the floor begins to warm
5. Set the floor temperature limit to match the floor type (see table below)

Floor Temperature Limits

Exceeding the floor's maximum temperature can cause permanent damage:

Always set the floor temperature limit in the thermostat to match the floor type.

Multi-Zone UFH

• Individual thermostats: One thermostat per zone, each on its own circuit — simple, no controller required
• Centralised controller (e.g. Heatmiser neoHub): One controller managing multiple neoStat thermostats — single-app management of all zones and more sophisticated scheduling

For multi-zone installs, plan consumer unit space for multiple RCBO circuits.

Common Issues

Related Documents

• Getting Started — Heating
• Smart Thermostat Wiring & Installation