NY-87-10-3 -- Heat Pump Defrost Controls: A Review of past, Present, and Future Technology PDF

Air-source heat pumps require a means of preventing or eliminating the accumulation of frost on the outdoor heat exchanger. Progress in the design and performance of heat pumps has been matched by progress in the functionality and reliability of defrost controls. Functional differences primarily center upon the basis for initiating defrost, either time or demand, with several parameters used to determine the need for defrost. Improvements in reliability have resulted from the technologies employed: electromechanical, solid-state, etc.

A review of defrost control functions and methods employed over the last decade is presented. Current technologies are summarized and a brief outlook of the future is offered.

Units: I-P