A poorly designed and installed ground source heat pump system will, effectively, be heating a property on electricity alone, which is by far the most expensive solution on a unit-by-unit basis. So what are the common problems that befall GSHPs?
1. Slinkies. A slinky, in heat pump terms, is when the pipes that collect heat from the ground are coiled up repeatedly and wrapped over each other. This greatly increases the amount of energy being extracted per square metre, to such an extent that the ground cannot recover. More heat is absorbed than replaced, resulting in a catastrophic drop in efficiency, and forcing the heat pump to rely on its electric back up to heat the property.
2. Cheap equipment: The delicate balance to strike with heat pumps is initial cost vs payback period. An impetus on cheaper initial cost always results in a less efficient system, that year-on-year is more expensive, and increases the payback of the system exponentially. Cheaper heat pumps have a much lower Coefficient of Performance (COP), basically the amount of kilowatts (kW) in heat produced to the amount of kWs of electricity to run the machine. A properly designed system will generate up to 5kWs of heating for every kW taken to run the machine, a cheap one can be as low as 1:1.3!
3. Lack of installer knowledge: In the rush to jump on the “green pound” bandwagon, a plethora of firms are embarking on heat pump installations without any prior experience in the field. They are not just like traditional plumbing systems and the effectiveness of the system hinges on everything being designed and installed correctly. There have been examples of companies insulating the very pipes supposed to be drawing heat from the ground, and then docking them into the wrong part of the heating system!
Picture by Patrick Hoesly
More information about ground source heat pumps from YouGen
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