CHICAGO — Four-way reversing valves are at the heart of heat pump systems, and are indeed necessary to their function. An American Society of Heating, Refrigerating and Air-Conditioning Engineers Inc.

Directional-control valves are vital in any pneumatic circuit, directing or blocking airflow to control the speed or sequence of operations. One method of classifying directional-control valves is by ...

Bob is a service technician who is well trained and nationally certified. However, he sometimes suffers from the same confusion that all technicians occasionally do - the facts that he gathers may or ...