In late 1979, Cargocaire Engineering Corporation began a plant expansion to include new sheet metal fabrication and assembly areas. In defining heating equipment capacities, it became rapidly apparent that the key factor dictating equipment capacity would be heating the outdoor air makeup required to offset the exhaust from the paint spray room. A decision was made to provide the spray room exhaust with a heat recovery system in the form of an air-to-air heat exchanger to reduce the heating requirement for heating equipment and reduce annual cost associated with heating make-up air. Experience with two other smaller spray booth installations suggested that a rotary regenerative exchanger would perform well in this application. While a static exchanger (plate type) was also installed in the same building on the welding exhaust, it was felt that the very high particulate loading of paint booth exhaust might slowly accummulate on the plates, increasing maintenance.

Also, the high air volume suggested that a plate exchanger might be impractical in terms of size. Previous experience on smaller installations suggested that a rotary, sensible air-to-air heat exchanger, equipped with an automatic purge section would be essentially self-cleaning if the particulate loading could be kept to dry rather than wet paint flecks.