Renewables
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Ensuring underfloor heating performance
With updates to Part L of the Building Regulations in England and Wales, and a wider focus on lowering emissions from buildings, underfloor heating systems have grown in popularity. Here, Mark Dowdeswell, senior category manager at Uponor discusses the key elements to consider in order to ensure the system performs correctly including design solution when integrating with heat pumps
T
he larger surface areas provided by underfloor heating make it the ideal solution to meet the heating needs of the property,
while complying with the maximum 55˚C flow temperature stipulated in Part L. However, there are certain factors that must be considered when designing and installing the system to ensure these requirements are met.
Insulation and thermal mass
One of the first and most important factors is the insulation of the property. Poor insulation will lead to significant heat losses and could mean that the underfloor heating cannot achieve the required room temperatures. This is primarily an issue with renovation projects as new builds constructed in line with the current standards will include the required levels of insulation. For retrofit installations in older properties,
wall and roof insulation is of course essential to prevent heat loss and should be upgraded wherever possible. However, a particular focus should be placed on the insulation of the floor. Effective insulation installed below the underfloor heating prevents heat loss into the subfloor and ensures more of the heat is directed up into the room. In addition, underfloor heating is most effective when there is sufficient thermal mass in the floor, such as the screed, to retain heat and minimise the energy consumption of the boiler or other heat source to maintain room temperatures. As an example, an effective floor construction that combines these two requirements would be 65mm of screed laid over 65mm of insulation, ideally on a concrete subfloor. Achieving this is not always possible in older
properties and often the floor height build-up is among the most important considerations. While there are many low-profile systems available, it is important to look for one that offers the smallest build-up while still delivering the required performance. For example, the Uponor Minitec underfloor system increases the floor height by just 15mm but still offers significant thermal mass as a screed-based product. A very low-profile system also maximises the thickness of insulation that can be installed.
12 December 2023
significantly lower than the 55º maximum, for example 40º, it may require the UFH installation to be adapted to achieve the target performance. Leading UFH manufacturers will be able to provide support on this and can recommend design solutions. As an example, the pipe pitches – the distance between the heating pipes – can be reduced to produce a higher output and a more reactive system. Furthermore, when working with lower
Flooring materials
Another factor to consider is the floor covering that will be used. Materials such as tile, stone, vinyl and laminate all work well with underfloor heating. For wooden flooring, it is recommended that a maximum thickness of 25mm is used to ensure good heat transfer. Carpet, while a popular choice, can pose an issue if the carpet itself and the underlay provide too much insulation. The recommendation is that the combined insulating properties of the carpet and underlay is no more than 1.5 Tog. It is often difficult to find and calculate this, so the best approach is to recommend that customers select products that the manufacturers have classified as ‘suitable for underfloor heating’.
Integration with heat pumps
One of the key reasons that heat pumps are considered so suitable for modern homes is their low flow temperatures. However, if this is
temperatures, it may be worth considering additional measures to reduce heat losses from other areas of the system. For example, with monobloc heat pump systems, ensuring that the water pipework from the outdoor unit is well insulated. This is especially important if there is an extended distance between the heat pump unit and the property.
Supplier support
Manufacturers can be an excellent source of technical support and guidance in ensuring the performance of underfloor heating. Therefore, this should also be a consideration when selecting systems. The right support can help streamline design and installation, especially where non- standard solutions are required. As with any heating system, there are many
factors that impact the performance of underfloor heating, from insulation to flooring material to the pipework design and installation. The Uponor team, which includes a range of product experts with experience in all types of properties, can help ensure all requirements are met.
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