The new APR-410 control provides full-capacity modulation for all sizes of direct-expansion air conditioning systems that use R-410A, a hydrofluorocarbon refrigerant. It continuously and automatically matches a/c system capacity-output to changing load conditions, which provides improved humidity control without overcooling the space. The control also eliminates many common maintenance problems associated with excess system capacity such as coil icing, liquid slugging, and excessive compressor cycling. It smoothly modulates the a/c system's capacity by varying refrigerant flow according to suction pressure, which changes with the temperature of air crossing the evaporator coil. According to the manufacturer, an a/c system equipped with the control continuously monitors the heat content of return air, so it is more economical than systems relying only on end-type controls, such as thermostats and humidistats.

Rawal Devices Inc., P.O. Box 2058, Woburn, MA 01888; 800-727-6447; 781-933-3306 (fax);;

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