Heat pumps

More and more developments are embracing the idea of using geothermal heat pumps to warm their homes. The idea of getting several kilowatts of energy out for every kilowatt of energy you pay for appeals both to the pocket and the ecological conscience.



In response to this growing interest in green technologies, Nu-Heat has joined forces with one of Europe’s leading suppliers of heat pumps. Nu-Heat can offer our customers a complete package of specification, design and supply for an integrated underfloor heating and heat pump system. We are, of course, happy to work with any designated heat pump supplier.



How heat pumps work



Whenever the sun is shining it warms the ground, building up its temperature to several degrees above that of the air and giving a source of energy that is available all year round. A ground source heat pump works by pumping a water mixture through pipes set into the ground in either a trench or borehole where it absorbs warmth from the inexhaustible free supply. Back in the heat pump, the process of re-cooling the water generates not only its own heat – like a refrigerator – but has the added bonus of the warmth that has been picked up from the ground.



Air source heat pumps work in a similar way, except they extract available warmth from passing air rather than from the ground. They are slightly less effective than ground source heat pumps, but this can be offset by the savings made on installation.



Because underfloor heating only uses water heated to between 45–55°C (as opposed to 75°C or over for radiators) it is the ideal partner for a heat pump. The amount of energy needed to heat the building is reduced, meaning the heat pump works efficiently and heating costs are kept to a minimum.



Heat pump suppliers state the efficiency of their units in terms of ‘Coefficient of Performance’. A CoP of five means that for every kilowatt of electricity put in you get 5 kilowatts of energy out in the form of warm water. The temperature is typically between 35°C and 45°C; much lower than you get from a domestic boiler. The units are perfectly capable of generating higher temperatures, but the CoP suffers, typically falling by 30% when delivering water at 50°c. The economic and ecological benefits are seriously compromised, because the efficiency of heat pumps is greatest at low output temperatures.



This is why the heat pump must deliver water at the lower end of the temperature range to heat your property. The supplier will do the necessary outline heating calculations and tell you what size of unit you need and what its CoP will be. It is unlikely that radiators working at the required low temperature could get that amount of heat into the rooms since they would have to be very large. With its much lower operating temperatures and greater floor areas, underfloor heating is the obvious option – the combination is already widely used in many countries such as Sweden where the two are regarded as natural partners.



If the insulation properties of the building are high and the floor coverings have low thermal resistance, the ‘driving force’ of the low temperature water used in underfloor heating is perfectly adequate. Your house can be comfortably warm and you can enjoy the financial benefits of the high CoP from the heat pump.



As specialists in the field, Nu-Heat recognises the importance of this increasingly important green energy supply which is why a section on the simple integration of the two technologies is included in the standard Installation Manual.