Underlay for Underfloor Heating
Underfloor heating has become increasingly popular in recent times.
The claimed advantages of energy efficiency combined with this obviously comfortable heat source means it is being specified for many new homes, particularly in the self build sector and in many commercial developments.
Can a carpet and underlay be used with underfloor heating?
Aside from the warm feeling of soft carpeting under bare feet, its primary role has been to ensure that during the winter months the cold coming through the floor is insulated and during the summer, the floor remains as cool as possible.
For these reasons, it’s easy to understand the concern with regard to the use of carpet with an underfloor heating system. All carpets and underlays are effectively a form of insulation.
A floor which has carpet and underlay will take slightly longer to get warm initially, but will remain warm for longer. Which underlay to use is also critical for best performance from the heating system.
The “thermal resistance value” is measured as a “tog” value.
Each underlay and carpet will have an individual tog value.
Research conducted by BSRIA (Building Services Research and Information Association) which is a test and research organisation providing specialist services in the construction and building industry in conjunction with the UHMA (Underfloor Heating Manufacturers Association) and the Carpet Manufacturers Association has proved that carpet can be used with underfloor heating with no impairment in performance of the system.
BSRIA’s work produced an accurate method of measurement of tog ratings for carpet and underlay. The carpet and underlay combination was tested in a test room built to the requirements of BS EN 442-2:1997, an underfloor heating system topped with 22mm floating chipboard deck was constructed in the room, with room sensors and measuring devices configured to effectively create ‘single plate’ test conditions.
This system was used to test the thermal conductivity of 19 combinations of carpet and underlay at flow temperatures of 40, 50 and 60ºC. Air temperature in the test enclosure was controlled to maintain 20ºC at the central inner room reference point 0.75m above the floor.
The results of the extensive testing showed that combinations of carpet and underlay functioned as if they had a resistance of 1.0 tog less than their combined published Tog value. (two plate method BS 4745).
The test was carried out in a test chamber which represented a room that was completely bare of furniture. In a real room, there would be furniture whose weight would press together the sections of the floor construction, and the effect of this is expected that this would also increase the actual output and subsequently reduce the Effective Tog.
The nature of their construction may determine their ‘real life’ resistance over a heated floor. Some carpets and underlay have air layers and cells within their structure and this may increase the thermal resistance, because air is a poor conductor. Radiant heat can pass easily through these air spaces and this could explain the difference between the ‘real life’ and published thermal resistance results.
Practical experience also suggests that as a carpet wears in age, with its fibres being compacted by foot traffic and as manufacturing fluff is vacuumed out, the resistance decreases even further. These factors combined with the improved connectivity achieved by using double sided tape or spray adhesives to fix the carpet, make possible even greater reductions in “real life” Tog ratings.
Getting the right underlay for your underfloor heating is key to running an efficient internal heating system.
We sell a range of Underfloor Heating underlays specifically designed for use with underfloor heating for carpets and "hard flooring" such as laminates and wood products.
For carpets we recommend Duralay HeatFlow for Carpets which has a very low 0.75 tog rating, but it is a heavy sponge underlay at 45 kgs per roll. We also have a PU underlay suitable for underfloor heating, Radiance with a tog value of 1.3 and a mere 18 kg roll weight. There are other underlays such as Extrastep (1.5 tog and 18 kg roll weight) which also has the Marine Wheel mark of excellence.
For a budget carpet underlay suitable for underfloor heating we have Novostrat Comfort Gold with a tog of 0.70 and only 8 kgs per roll. This option doesn't have the same comfort as the Sponge and PU underlays.
Underlay for underfloor heating is available in abundance. Carpet Underlay Shop has a wide range of underfloor heating underlay that can be used with carpets, laminates and wooden floors. The underfloor heating carpet is perfect for making the transfer of heat efficient, in the winter your home will remain insulated rather than losing heat through the ceiling.
The main purpose of the underlay for underfloor heating is to ensure maximum heat transfer and to provide extra underfoot comfort. The underfloor heating carpet is becoming increasingly more popular for its ability to prolong the life of the carpet above, allowing you to maintain high standards for longer.
If you have any technical questions about any of our products please call our sales team on 01274 905413.