Geothermal Heating
Geothermal Heating - how it works
The earth’s surface acts as a huge solar collector, absorbing radiation from the sun. In this country the ground maintains a constant temperature between 11°C and 13°C, several meters below the surface. Geothermal Heat Pumps take advantage of this by transferring the heat stored in the earth or in ground water to homes in winter. Through compression, heat pumps can ‘pump up’ heat at low temperature and release it at a higher temperature so that it is sufficient for home heating. A heat pump looks similar and can perform the same functions as a conventional gas or oil boiler, i.e. space heating and sanitary hot water production
Installation in the Home
The system has three main components: a series of pipes in the ground, a heat pump and a heat distribution system. Lengths of plastic pipes are buried in the ground, either in a borehole or a horizontal trench near the building to be heated or cooled. Fluid, normally water with anti-freeze, absorbs heat from the soil. The heat pump removes the heat from the fluid, upgrades it to a higher temperature (by increasing the pressure). This extracted heat is then transferred to water for use in the home. The heated water is now distributed around the home usually in underfloor heating pipes.
Payback and Maintenance
The initial capital costs of installing a Geothermal Heat Pump system is usually higher than other conventional central heating systems. However, under the Greener Homes Scheme, there are now grants available which will reduce initial costs significantly. A large proportion of the outlay will be for the purchase and installation of the ground collector. Once installed the system is among the most energy efficient and cost effective heating systems available.
Typically, four units of heat are generated for every unit of electricity used by the heat pump to deliver it, and the payback is typically about 8 - 10 years. The life expectancy of the system is around 20 years. Once installed a heat pump requires very little maintenance and anyone installing a heat pump should speak with their installer regarding a maintenance agreement.
Before installation it is important to locate an experienced installer who can advise on the following:
- Find the best heat source available - ground or water
- Advise on the best heat pump available. As this is a relatively new type of heating in Ireland, ask to meet some of their previous clients
- Make sure it is sized right for your heating requirements
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