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How Air-Source Heat Pumps Work

Heating with cold air? Cooling off with hot air? Heat pumps performing these feats (especially mini-splits and VRF systems) have taken off, but how do they work?

Air-source heat pumps have been growing rapidly in popularity over the past decade. In many regions, simple point-source mini-split systems are now the leading choice for designers and builders of high-performance green homes, and more sophisticated variable-refrigerant-flow (VRF) multi-split systems are popular in multifamily and commercial buildings.

All heat pumps perform the same basic function: they move heat from one place to another, using electricity. In heating mode, air-source heat pumps move heat from the outside air into a building; in cooling mode, they take heat from the inside air of the building and dump it outdoors, cooling the indoor space in the process.

Published February 3, 2014