Air Source Heat Pumps (ASHPs) are the most prevalent form, extracting heat from the outside air. They are simple to install and often inexpensive, though their efficiency can drop in extremely cold locations.
earth Source Heat Pumps (GSHPs), sometimes known as geothermal heat pumps, draw heat from the earth or a nearby water source. These systems are very efficient because ground temperatures are more constant than air temperatures, but they take up more room and cost more to install.
Water Source Heat Pumps: