Ground Source Heat Pumps work using the principal of heat transfer. Heat transfer uses a small amount of electrical energy to transfer low temperature heat from the ground to higher temperature heat, suitable for heating water to usable temperatures – essentially transferring heat from a ‘free heat source’ like the ground to a ‘heat sink’ like your home. This is a similar operation to a refrigerator – but in reverse. It uses a process known as the vapour compression cycle.
All ground types are different and require thought and design to determine how much heat can be obtained, i.e., the thermal conductivity. There are two options for installing the pipes that collect heat from the ground, the most important factor is surface area, which can be achieved either vertically via boreholes or horizontally via trenches.
Boreholes tend to be a better option when space is at a premium, we drill up to 180m straight down and the hole is around 6 – 8 inches in diameter, leaving no trace once completed. An average 4-bedroom house might need 3 boreholes, spaced 8 metres apart so this is a very efficient solution in tighter spaces.
Trenches are the most cost-effective way of installing a Ground Source Heat Pump. Pipes need to be located under the frost line at around 1.2m deep, trenches are roughly 1m wide and an average 4-bedroom house may need 350 linear metres of trenching to provide enough heat transfer for the property’s heating and hot water demand.
Manufacturer’s life expectancy of a GSHP system is more than 20 years and there are minimal maintenance requirements. Annual servicing can be as little as £225 per annum and warranties can be as long as 7 years giving you total peace of mind.
During winter, the frost acts as an insulator and temperatures in the ground at 1.2m deep are consistent throughout the seasons at roughly 10 degrees C.