Heat pumps can save operating energy costs when retrofitted to industrial evaporators. Whether an evaporator is worth retrofitting depends upon its size, operating cycle, and type of heat exchanger design.

Several philosophical decisions need to be made early in a retrofit: the roles of evaporator vendor, users, and engineerig firm; the system arrangement; and the desired trade-off between capital and operating costs.

Compressor selection depends upon the volumetric flow and lift required. Suitable machines include centrifugal single-stage fans and compressors, screw compressors, and rotary lobe blowers. Details of seal design, materials of construction, and turndown are discussed.

System details important to the success of the retrofit include: entrainment separation, compressor vapor piping, compressor protection, compressor motor starting, and system control philosophy.

Units: Dual