Site conditions and installation
Heating systems under wooden flooring are normally low temperature water based systems but electrical systems may also be used. The most essential element of any good underfloor heating system are accurate temperature control and even temperature distribution. It is essential that the surface temperature of the subfloor remains below 27°C (at a room temperature of 18-22°C) or excessive shrinking will occur.
In the design stage calculations of the heating requirements for the building will define if the underfloor heating will perform satisfactorily as the only source of heating. As a guideline the maximum energy output from the floor will be in the region of 100W/m² based on a maximum surface temperature of 27°C. In the event that a higher output is required supplementary heating will need to be specified.
Before the floor is laid it is essential that the heating system is operated at 70% of normal output for 2 weeks prior to the installation of the wood flooring; this ensures that the system is operating correctly, helps to remove residual moisture in screed based systems and ensures that the control systems function properly. Please note that where the heating pipes are housed in polystyrene or clipped to battens (these should be kiln dried) or joists it is essential that heat distribution plates are used.
Ambient room humidity should ideally be between 55 to 65%.
Golden rules for success
- Good control systems are essential: never exceed 27°C at a room temperature of 18-22°C.
- Operate the system constantly at 70% of its maximum permitted temperature for 2 weeks prior to installation.
- Get the subfloor flat, undulations in the subfloor will cause poor contact to the heated subfloor resulting in cold spots, they may also cause squeaking and gaps.
- Remember that the maximum surface temperature of the heated wood floor should not exceed 27°C (even under rugs and furniture).