How do they work?
Ground source heat pumps differ depending on how the pipes are laid. The three main configurations are:
- Horizontal ground-loops
- Coiled ground-loops
In the horizontal ground-loop configuration, an area in your garden, depending on the size of your system, is excavated to a depth of approximately 1.5 -2m. Next pipes are laid in a similar fashion to the pipes you would see on the back of a fridge.
A coiled ground-loop system follows a similar procedure to the horizontal ground-loop configuration. However, because coiled loops allow more surface area in a smaller space than horizontal ground-loops, less area needs to be excavated. However, the downside to coiled ground-loops is that because the pipes overlap, they compete for the same heat meaning that this setup is less efficient than the former.
If you have limited space to install a ground source heat pump then a bore-hole could be a possible option. This involves a hole, approximately 6 inches in diameter, being drilled to a depth of 60-100m. A number of pipes are then fitted in the hole to collect the heat. The depth and number of bore-holes you need will, again, depend largely on the size of the system you wish to install. Although bore-holes take up much less space than ground-loops, the cost to drill the hole can be expensive.
Whatever pipe configuration you choose the way the system works will be the same:
- A special anti-freeze solution is cycled through the pipes by the pump, collecting heat from the ground which is at a constant temperature of 10 – 12° C at that depth
- When the solution reaches the water cylinder, stored indoors, a compressor boosts its temperature to the required level depending on your heating system
- The high temperature solution is run through sealed pipes contained in a water tank, which heats the water ready for use
- The heated water from the tank is circulated through your central heating system to heat your home
- The cooled solution flows back to the ground to collect more heat.