A TAILORED SOLUTION ENSURES THE BEST FIT

When modern underfloor heating first appeared in the UK – back in the early 1980’s – it was treated with great suspicion. It was a technique that required specialist designers, specialist installers and just a hint of magic beneath a dark moon.

Great effort has been expended to reassure customers, professionals and end users alike, that underfloor heating can be a no-risk, standard solution for all types of building. And so it can be, but in the drive to promote higher and higher volume sales of “standard” systems, perhaps we’ve overlooked the fact that British buildings are very far from standard and that construction methods are changing.

One size does not fit all. If you want the best results, some projects will require special treatment and perhaps a little specialist technical support.

Underfloor heating is hugely popular in continental Europe where most underfloor companies originate or source their products and their technology. Screeded systems dominate that market and little attention is paid to other methods of construction. In the UK we make much more use of dry timber constructions in buildings and we also have the oldest building stock in the world - with some of the oldest timber!

If you’re required to install an underfloor heating system in a listed building, the kind of techniques that are perfect for concrete floors in a new highly insulated German house may not be the most suitable. Care has to be taken to deal with irregular joist spaces and to provide sufficient power to overcome the high heat losses of these older “leakier” buildings.

All of this sits against a background of a drive for ever greater energy efficiency.

Products designed specifically for use in UK constructions both old and new can be crucial to success. Equally using a supplier that can offer a variety of project-matched solutions rather than the one-size-fits-all approach means that the installation will be straightforward and performance guaranteed.

Technical

There are some specific technical points, which should also be borne in mind.

For example, underfloor heating in timber floors perform well when there is a good conductive pathway between the pipe and the floor surface. Timber floors by their nature are not solid, they have air gaps. It is these gaps that can reduce the performance of any system.

To establish the facts my own company had Timoleon systems designed to eliminate the air gap problem independently tested at BSRIA’s laboratory. Those tests revealed that the Timoleon approach can transfer heat up to 60% more heat into the floor efficiently than systems that use the air gap to transfer heat. That means the system will achieve a higher output or that it can run at a lower water temperature.

Sixty per cent is a very significant number, but there are other factors that may multiply overall efficiency even higher.

Heat pumps will work at their highest COP when producing low temperature water. This is why heating pumps and underfloor heating are well suited – this form of heating uses much lower water temperatures than radiators. However, different underfloor heating systems work at different water temperatures. The better the product is at transferring energy the lower the water temperature it needs and therefore the more efficient the heat pump.

Put another way a really good underfloor system can produce the same heat output from water up to 10ºC cooler. With most heat pumps this represents an improvement in efficiency (COP) of over 20%!

“All very well in theory,” the more sceptical reader may mutter, “but how does the theory translate into practice?”

Here’s an example of how we tailored an underfloor heating solution powered by renewable energy sources for a leading market research company’s new headquarters building.

An air to water heat pump combined with solar panels are the prime energy sources for the new premises of Marketing Means at Ashburton in Devon.

The former railway goods shed – a Grade 2 listed building - is being converted into a 2-storey head office for the company, which uses telephone surveys and face-to-face interviews to research views on subjects ranging from politics to customer services.

Listed status

The refurbished building, which is located within Dartmoor national park, has been the subject of a major upgrade of its energy profile – where this does not conflict with its listed status.

The windows, floors and ceiling are being insulated to current building regulations. Two of the external walls are also being insulated to the same high standard. Elsewhere, however, the original un-insulated stone has had to be retained giving rise to high heat losses in certain areas.

To overcome this problem, while retaining a high COP for the heat pump, we devised an underfloor heating solution using a number of specially developed products.

The ground floor of the project features one of the first installations of Timoleon FoilBoard SRB (screed replacement board). This comprises high efficiency insulation material with a layer of aluminium bonded to the upper surface – into which channels are preformed ready to accept Timoleon’s 15mm polybutylene heating pipe. The system is then topped with a floating floor of screedboard.

At Marketing Means the pipework centres have been closed up to 150mm centres rather than the standard 200mm to maximise the efficiency of the heat pump - achieving full comfort conditions from comparatively low temperature water.

Maximum output

On the upper storey a Timoleon Toron system has been used to achieve maximum output in order to overcome the losses through the old stone walls.

The Toron flooring system combines a floor deck with an underfloor heating system in a single, structurally loaded entity.

The new, patent pending, system comprises 22mm thick panels of moisture resistant, flooring grade chipboard, ready tongue and grooved and routed to accept Timoleon's 10mm polybutylene underfloor heating pipe.

Pipe is fitted into the channels on the upper surface of the chipboard modules - thus ensuring that the heating element is as close to the floor finish as possible. This maximises the heat output of the modules, while reducing the temperature of the water required.