When selecting an air-source heat pump, consider the following three characteristics carefully: the energy efficiency rating, sizing, and the system's components. Energy Efficiency Ratings In the United States, we rate a heat pump's energy efficiency by how many British thermal units (Btu) of heat it moves for each watt-hour of electrical energy it consumes. Every residential heat pump sold in this country has an EnergyGuide Label, which features the heat… Read more