Heat Pumps are a renewable, low maintenance form of heating that is already widely available throughout the UK.
Benefits of using a ground source heat pump
Heat pumps offer an energy-efficient alternative to conventional heating and cooling methods such as gas, oil or air conditioning. Like your refrigerator, heat pumps use electricity to move heat from a cool space to a warm space, making the cool space cooler and the warm space warmer. During the heating season, heat pumps move heat from the cool outdoors into your warm house and during the cooling season, heat pumps move heat from your cool house into the warm outdoors. Because they move heat rather than generate heat, heat pumps can provide equivalent space conditioning at as little as one quarter of the cost of operating conventional heating or cooling appliances.
The most common type of heat pump is the air-source heat pump, which transfers heat between your house and the outside air. If you heat with electricity, a heat pump can trim the amount of electricity you use for heating by as much as 30% to 40%. High-efficiency heat pumps also dehumidify better than standard central air conditioners, resulting in less energy usage and more cooling comfort in summer months. However, the efficiency of most air-source heat pumps as a heat source drops dramatically at low temperatures, generally making them unsuitable for cold climates, although there are systems that can overcome the problem.
For homes without ducts, air-source heat pumps are also available in a ductless version called a mini-split heat pump. In addition, a special type of air-source heat pump called a “reverse cycle chiller” generates hot and cold water rather than air, allowing it to be used with radiant floor heating systems in heating mode.
A ground-source or water-source heat pumps achieve higher efficiencies by transferring heat between your house and the ground or a nearby water source. Although they cost more to install, ground source heat pumps have low operating costs because they take advantage of relatively constant ground or water temperatures. Whether this type of heat pump is appropriate for you will depend on the size of your plot, the subsoil, and the landscape. Ground-source or water-source heat pumps can be used in more extreme climates than air-source heat pumps, and customer satisfaction with the systems is very high.
FAQ Ground Source Heat Pumps
1. How efficient is a ground source heat pump system?
Modern systems can be very efficient. For each kilowatt of electricity used to run the heat pump, three to four kilowatts of heat can be delivered to the building. The efficiency of a GSHP installation is very dependent on the quality of the design and installation. The efficiency of the installation is improved by utilising solar recharge of the ground.
2. Are ground source heat pumps new?
GSHP systems are common, particularly in the Sweden, Switzerland, Germany, USA and Canada. The principles of ground source heat pumps were first described by William Thomson (Lord Kelvin) in the 1850s and have been continuously developed. Since their conception over 50 years ago, both the technology and application methods have greatly improved their efficiency and reliability. They now provide a proven, cost-effective, safe and environmentally friendly alternative to fossil fuels.
3. How large are ground source heat pumps?
A heat pump for a house is about the size of a large fridge. More powerful heat pumps for commercial buildings do not increase in size or price as much as they do in power output.
4. Can a GSHP supply hot water?
Yes. Many domestic systems are able to heat domestic hot water via a modern high efficiency indirect water cylinder. This can be either by a large surface coil within the hot water cylinder or by the use of a heat exchanger.
5. Can GSHPs provide cooling?
Yes. Reverse-cycle heat pumps can deliver both heating and cooling very effectively. Cooling provided by heat exchange with cold ground is inherently more efficient than air conditioning which typically exchanges heat with hot air.
6. Would a ground source heat pump system be suitable for a well-insulated house?
Yes. Almost all new houses in the UK are designed to meet Building Regulations and should be able to benefit from a ground source heat pump. Building Regulations have been designed to conserve fuel, reduce heat losses and ensure greater energy efficiency, in order to ensure that all modern properties need less heating. For a well-insulated building the size of heat pump will be smaller, will need smaller ground loops and will therefore be less expensive.
7. Can a standard domestic electricity supply be used?
Yes. Heat pumps are designed to run on a standard UK single-phase supply. However, a three-phase supply is a preferable option and will be essential for larger installations.
8. If I install underfloor heating. Is this a good idea?
Yes. Ground source heat pump systems are ideally matched to modern warm temperature underfloor heating. A heat pump transfers heat at a higher coefficient of performance if it delivers to a large warm water circuit (like underfloor heating) rather than a small high-temperature circuit (like wall-mounted radiators).
9. Can radiators be used instead of underfloor heating?
Yes, but you will need larger radiators or SMART radiators that are fan coils, sized for the typical 45°C to 50°C water temperatures obtained from efficient GSHP systems. If your house is well insulated they may be suitable. Your installer will need to check how big they would have to be and the space they would take up. Modern die cast aluminium radiators are very efficient and smaller than conventional radiators. Upstairs is usually less of a problem as bedrooms are normally kept at lower temperatures.
10. Can the heat pump be installed outside or in a garage, basement or outbuilding?
Yes. This normally means the pump will be nearer to the pipe connections to your ground loops, which often makes the whole system easier to connect.
11. Can trenches be installed on a downward sloping site?
Yes, provided the trenches can be dug, a moderate downward slope is not a problem. Consideration needs to be given to purging air from a system with ground loops higher than the heat pump.
12. I have some very wet land. Can I use this?
Yes, wet land is better at conducting heat so, as long as a trench can be dug, it is ideal.
13. Are GSHP systems environmentally friendly?
Yes. In the UK, there is now a strong move towards alternative technologies that are sustainable and environmentally much more acceptable. 40% of CO2 emissions are derived from the heating of buildings. By using renewable sources of energy to heat your property you can help to reduce these carbon emissions, particularly when compared to burning fossil fuels such as oil. Most electricity suppliers are now offering ‘green’ electricity from a renewable energy source and, if you use this to power your heat pump, your property will be totally heated from renewable energy with zero carbon emissions.
14. Are Ground Source Heat Pumps dangerous?
There are no hazardous gas emissions, no flammable oil, LPG or gas pipes, no flue or chimney and no unsightly fuel tanks. GSHP systems have absolutely NO site emissions. There is, therefore, no need for safety checks.
15. Are Ground Source Heat Pumps noisy?
No, a ground source heat pump makes less noise than a gas boiler, and very much less than an air source heat pump which drives a fan to extract heat from ambient air.
16. What about servicing and maintenance?
As with any valuable equipment; we would recommend that it is covered by an annual maintenance agreement. However, routine maintenance requirements are very low. A ground source heat pump can be expected to last over 20 years – longer than a combustion boiler – and the ground heat exchanger should have a life of over 50 years.
Ground source systems are automated. Because they come with low maintenance, low running costs, low noise and are out of sight, they are often referred to as “invisible heating systems”.
17. How do running costs compare with conventional alternatives?
In a modern, well insulated house, a ground source heat pump can offer very high efficiency and low running costs. An oil-fired boilers cost considerably more to run, and electric heating is at least three times as expensive. Modern condensing gas boilers are more expensive to run at current gas prices, and gas prices are set to rise. Also, all fossil fuel boilers need regular servicing to maintain efficiency and check safety.
18. What are the costs?
The initial purchase costs of a ground source heat pump system are more than conventional oil or gas fired boiler. The initial capital expense is offset by lower running costs, lower maintenance and low servicing requirement. There is also the security of knowledge that the majority of your heating and cooling energy comes out of your ground, is under your control and will not increase in price.
Be careful to avoid judging an installation on price alone. It is more important to ensure you have a well designed system if your aim is to save money over the life of the installation.
19. Are grants available to reduce costs further?
Yes, the government introduced Renewable Heat Incentive for ground source heat pumps installed in domestic buildings at 19.10 p/kWhr on 1st July 2014.