An HVAC system that depends on the temperatures below the ground surface as an operation factor is a/an______?

• A. Air-source heat pump
• B. Geothermal heat pump
• C. Conventional furnace
• D. Absorption chiller

Answer: (B)

The system that relies on temperatures below the ground surface is using the earth as a stable heat source and sink. A geothermal heat pump takes advantage of the relatively constant underground temperatures to transfer heat to or from the building, which makes heating and cooling more efficient than systems that depend on outdoor air. The buried loop exchanges heat with the ground (either closed loop circulating fluid or open loop with groundwater), so indoor comfort can be achieved with higher efficiency year-round. This is different from an air-source heat pump, which uses outdoor air; a conventional furnace, which burns fuel to generate heat; and an absorption chiller, which uses a heat source to drive an absorption cycle.