Underfloor Heating
Floor Sensor Placement for Underfloor Heating Control
Floor sensors let a thermostat limit slab temperature directly, and their conduit needs securing carefully before the screed pour.
Many underfloor heating control setups use a floor probe sensor in addition to, or instead of, a room air sensor, feeding back the actual temperature of the screed slab so the thermostat can limit floor temperature directly. That sensor sits inside a small conduit embedded in the screed between two pipe runs, and getting its position and protection right during the pour matters for accurate readings later.
We work from the electrician's or heating installer's marked sensor position, checking the conduit is securely fixed at the correct depth roughly midway between adjacent pipes, so the reading reflects the slab generally rather than being unduly influenced by one pipe run.
The conduit and its lead-out need protecting during the pour in the same way as any other service running through the screed, since a crushed or displaced conduit can mean an inaccurate reading or a sensor that can't be replaced without disturbing the finished floor.
Floor Sensor Placement — the points that decide it
- Floor probe sensors sit in a conduit embedded within the screed depth
- Sensor position is normally marked by the electrician or heating installer before pouring
- Placing the sensor midway between adjacent pipe runs gives a more representative reading
- Conduit needs to be firmly fixed and protected during the pour like any other service
- A displaced or damaged sensor conduit can be difficult to correct after the floor is finished
- Floor sensors are often used to limit maximum slab temperature for floor covering protection
- Some control strategies combine a floor sensor with a room air sensor for both slab limiting and comfort control
- Sensor cable or conduit routing back to the thermostat position should avoid crossing pipe runs unnecessarily
Why floor sensors are used
A floor sensor gives the control system direct information about slab temperature, which is particularly useful where a floor covering has a maximum recommended surface temperature, since it lets the thermostat cap output before that limit is reached rather than relying solely on air temperature.
Protecting the conduit during pouring
As screed is placed and raked around the sensor conduit, care is taken not to disturb its fixing or drag it sideways, and the lead-out route to the wall or switch position is checked before pouring so it isn't buried unexpectedly.
Combined floor and air sensing
Some thermostats use a floor probe alongside a room air sensor, limiting maximum slab temperature for covering protection while still controlling comfort based on air temperature. This combined approach gives more nuanced control than a floor sensor used in isolation, particularly where a heat-sensitive covering like engineered wood is fitted.
The two sensors serve different purposes: the air sensor drives day-to-day comfort control, while the floor sensor acts more as a safety limit, capping output if the slab approaches a temperature that could damage a sensitive covering even if the room itself hasn't yet reached the set comfort temperature.
Marking and recording sensor locations
Before pouring, we note where each sensor conduit sits relative to the pipe layout, keeping a simple record or marked-up drawing that can be referred to later if a fault develops or if further work near that area is planned, since the conduit itself becomes invisible once the floor covering is fitted.
This record also helps avoid accidental damage during later work, such as fixing skirtings or drilling for other services, by giving a clear reference for where a sensor conduit runs beneath the finished floor.
What happens if a sensor needs replacing later
A sensor probe itself can usually be withdrawn and replaced within its conduit without disturbing the screed, provided the conduit remains intact and the original route is known, which is one reason keeping a clear record of the conduit position at installation is worthwhile.
If the conduit itself has been damaged or crushed, replacing the sensor becomes far more invasive, which reinforces why protecting it carefully during the pour is preferable to relying on being able to fix problems afterwards.
In short
Floor sensors let a thermostat limit slab temperature directly, and their conduit needs securing carefully before the screed pour.
Fitting floor sensors as part of your UFH design?
We coordinate sensor conduit placement and protection with your electrician ahead of the pour.
Or call our landline on 01392 237700
Floor Sensor Placement — your questions
Fitting floor sensors as part of your UFH design?
We coordinate sensor conduit placement and protection with your electrician ahead of the pour.