In September, 1972 an agreement between ASHRAE Research Canada and the University of Manitoba to develop "Standard Procedures for Rating Air-to-Air Heat BlCchangers" was ratified. The acceptance of standard procedures for testing will, in addition to providing comparable literature in this field, eliminate inconsistencies in terminology (a more precise expression for efficiency or thermal effectiveness is definitely required).

The study of air-to-air heat exchangers at the University of Manitoba was initiated by the Federal Department of Health. Funds were provided for an investigation at a local hospital and later for a laboratory installation which proved to be the prototype of our present facilities.

The intent is to describe the testing that was completed in 1973. This involved performance testing to determine the capacity, thennal efficiency and the microbiological and exhaust air carry-over of rotary heat exchangers. Only general relationships are presented in this paper as all actual test data is being withheld until the completion of the project