ISO 21773:2021

This document specifies methods for testing and characterizing the performance of air-to-air heat/energy exchangers when used as devices to transfer heat or heat and water vapor between two airstreams used in ventilation systems. It also specifies methods to characterize the performance of exchangers for use in calculation of the energy performance of buildings. This document is applicable to:
—    fixed-plate exchangers (also known as recuperators),
—    rotary exchangers, including heat wheels and total energy wheels (also known as regenerators),
—    heat pipe exchangers using a heat transfer medium, excluding those using mechanical pumping.
This document does not provide a method for measuring the response of exchangers to the formation of frost.