What is the differnce between an air source and a ground source (geothermal) heat pump?
An air source heat pump extracts heat from the outdoor air in heating mode, while a ground source unit extracts heat from the ground. The temperature deep in the ground is constant at about 10C (50F) so a ground source unit can operate more efficiently when air temperatures are below 10C, but will be less efficient at temperatures above 10C. In BC’s mild climate, this means that the energy savings of a ground source unit are marginally greater than with an air source unit. However, ground source units are much more expensive than air source units. They usually cost over $20,000. A company that installs geothermal units quoted the price of a geothermal unit as $35,000-$50,000 in the Vancouver Sun. An air source unit can provide most of the savings for a fraction of this cost, so they are much more popular and the only ones we install. Are heat pumps new? No, they share the same basic technology as refrigerators and air conditioners which were invented over 100 years ago. Heat pumps were