Are Ground Source Heat Pumps Good For My Home?
What are Ground Source Pumps?
The technology used is the same as that used in refrigerators. Just as a fridge extracts heat from the food and transfers it into the kitchen, so a ground source heat pump extracts heat from the earth and transfers it into a building.
Radiation from the sun heats the earth. The earth then stores the heat and maintains just two meters or so down, a temperature is around 8-10°C even throughout the winter. A ground source heat pump uses a ground heat exchange loop to tap into this constantly recharge heat store to heat buildings and provide hot water.
The Advantages of Ground Source Heat Pumps
Ground Source Heat Pumps save money. Heat pumps are much cheaper to run than direct electric heating systems. GSHPs are cheaper to run than oil boilers, burning coal, LPG or gas. This is before taking into account the receipt of RHI, which amounts to over $3,000 a year for an average four bedroom detached house – larger than for any other technology under the RHI.
Because heat pumps can be fully automated they demand much less work than biomass boilers.
Heat pumps save space. There are no fuel storage requirements.
No need to managed fuel deliveries. No risk of fuel being stolen.
Heat pumps are safe. There is no combustion involved and no emission of potentially dangerous gases. No flues are required.
GSHPs require less maintenance than combustion-based heating systems. They also have a longer life than combustion boilers. The ground heat exchanger element of a ground source heat pump installation has a design life of over 100 years.
Heat pumps save carbon emissions. Unlike burning oil, gas, LPG or biomass, a heat pump produces no carbon emissions on site (and no carbon emissions at all, if a renewable source of electricity is used to power them).
GSHPs are safe, silent, unobtrusive and out-of-sight: they require no planning permission.
Heat pumps can also provide cooling in summer, as well as heating in winter.
A well-designed ground source heat pump system is likely to increase the sale value of your property.
How to Install Ground Source Heat Pumps
You will either have a horizontal ground array installed, or boreholes can be dug for a vertical installation. The choice will depend on the space available and your ground conditions.
Horizontal arrays can come with straight or slinky pipes. People who advocate the use of straight pipes don’t tend to like slinkies, and vice versa. The reality is that both work, as well as each other and whatever your chosen supplier is happiest with, will be fine.
The key is ensuring there is enough ground to allow pipes to be properly spaced. The calculation for clay soil is 50m2/kW output, so a 14kW heat pump needs 700m2 of unshaded land. Bear in mind that the array needs to be kept at least 5m from any boundary, and that straight pipes need to be 3m apart and slinkies 5m apart.