As fuel bills soar again this year, homeowners may start feeling the pinch. It is worth knowing that heat pump technology, when integrated with warm water underfloor heating, can generate fuel savings of up to 70 per cent. Team this with claims that ground source heat pumps can produce around 50 per cent less carbon dioxide, compared to a conventional boiler and the environmental benefits are considerable.

What is the best approach for the selfbuilder when trying to integrate renewable technologies and underfloor heating?

This article looks at combining heat pump technology with warm water underfloor heating, considers the importance of insulation and looks at how you can easily establish whether your project is suitable for a heat pump.

Heat pumps

Firstly, selfbuilders can quickly determine whether their project is suitable for use with a heat pump by completing a series of short questions, such as detailing the approximate internal size of a property and confirming whether insulation is present, as set out in Nu-Heat’s online ‘heat pump guide’. The answers selected will give a general guide to the likelihood of a heat pump being able to deliver both the heating and domestic hot water needs of the property. Visit www.nu-heat.co.uk/heatpumptool for more information. 

Heat pumps – a brief overview

Ground source, air source and exhaust air heat pumps are designed to replace conventional gas or oil-fired boilers. They are at their most efficient when the water produced is between 35˚C and 45˚C, far lower than would be practical for a conventional radiator system typically needing water at 65˚C or higher, but ideal for warm water underfloor heating.

Heat pumps are perfectly capable of producing water of a higher temperature but the Coefficient of Performance* (CoP) suffers, falling to between 3 and 4 when delivering water at 50˚C, significantly compromising the economic and ecological benefits of the system. Under test conditions, the Nu-Heat ground source model has exceeded a CoP of 5 and Nu-Heat will always work in consultation with selfbuilders to maximise the energy performance of each project.

* A CoP of 5 means that for every kilowatt of electricity put in, you get five kilowatts of energy out in the form of warm water.

Combine heat pumps with UFH to further enhance energy savings

The efficiency of any heat pump is improved when the temperature of the water flowing to the heating system is reduced. This makes warm water underfloor heating the obvious choice as most underfloor heating systems are designed to operate with a flow temperature of between 35˚C and 45˚C.

Installing underfloor heating need not be complicated, increase build costs or alter established construction methods. Whilst the rise in steel prices has contributed towards more expensive radiators, the rise in sales of underfloor heating has resulted in a more competitive market. The wide range of different design options now available guarantees straightforward integration into any floor construction.

The importance of insulation

Levels of insulation within a building are of key importance as the better insulated the house, the more efficient and cost-effective to run the heating system will be. At its simplest, the more insulation in a building, the lower its heating bills and the colder the climate, the more important a high standard of insulation becomes.

UK building regulations have progressively required higher insulation standards and it is both easier and more effective to achieve a high standard of insulation during the construction of a property or during major renovation work.

In practice, even a building insulated to well above the building regulation requirement will always need some level of heating; first, because there needs to be some passage of air from the outside to maintain freshness and second, because insulation does not itself create warmth, it simply helps to retain it. With underfloor heating a high proportion of the warmth is radiant, with little generation of convection currents, so not only does it feel more comfortable, but the ventilation heat loss from the building is reduced.

Because the warmth passes into the room from the floor, it is important to prevent downward heat losses into the ground or the floor below. In a new building that meets the regulations, there will always be an adequate level of floor insulation, but if a building is being refurbished and no extra insulation is provided, this may not be the case.

Floor insulation requirements with underfloor heating

Ground floors or floors over unheated areas should have at least 70mm Celotex or other rigid PIR type insulation directly below the heating pipes or diffuser element.

Insulation with a minimum R value of 0.75m2K/W (approximately 30mm polystyrene or 100mm mineral wool or equivalent) is required in intermediate floors over heated areas. This applies to most apartments and domestic housing.

One-stop-shop

Nu-Heat has invested heavily in product development and training, with new products and floor constructions designed specifically to meet the requirements of Part L of the Building Regulations, and to enable heat pumps to work at optimum efficiency. Expert guidance on suitable heat sources and Part L compliance strategies is provided and Nu-Heat is well placed to lead selfbuilders through the design process of a combined underfloor heating and heat pump system as the company now provides both energy-saving products. Purchasing the heat pump and heating system from one supplier means they will be totally compatible; there is just one point of contact; and no conflicting advice.

All Nu-Heat designs meet the precise needs of each individual project with detailed installation information shown on layout drawings. Installation can be handled either by the self-builder, an installer recommended by Nu-Heat or your preferred plumbing contractor. The process is straightforward, requires no prior experience or specialist tools and is supported by award-winning documentation.

Finally, provision of a user guide will ensure that homeowners fully understand both the underfloor heating system and the heat pump and how to gain the most benefit from their energy efficient features.

For more information on the products included in this article, or to discuss your project in more detail, please call 0800 731 1976. Alternatively visit www.nu-heat.co.uk.