The best heat pump model series by York is the Affinity brand. This line of two heat pumps combines superior efficiency and comfort over other York models.
The York Affinity series of heat pumps, consisting of the YZH and YZF models, are rated by Energy Star to use an estimated 15 to 25 percent less energy than standard models. They come equipped with a Demand Defrost system that better endures cold weather use by minimizing defrost cycles. Also featured is a QuietDrive system that allows the heat pumps to operate at muted noise levels. This is accomplished with a swept-wing fan, isolated compressor compartment and composite base pan that minimizes vibration.
The Affinity series, which garnered top marks in efficiency among York heat pumps, is reviewed on four ratings. There are two cooling ratings, the Seasonal Energy Efficiency Ratio and Energy Efficiency Ratio. These are weighed alongside two heating ratings, the Annual Fuel Utilization Efficiency and Heating Seasonal Performance Factor.
Likewise, the comfort rating of the Affinity models is measured from motor and compressor performance, controllability and sound output during operation. These heat pumps have capacities of 2 to 5 tons of operation, equal to a British Thermal Unit range of exchange of 24,000 to 60,000 per hour.