Air to Air Heat Exchangers

I Overview
Air to air heat exchangers transfer heat energy between two separate air streams. They allow two air streams to come into close contact with each other – close enough that the energy in one can be transferred to the other, but not so close that contaminants are also exchanged.

II Applications
Air to air heat exchangers can reduce energy usage for space conditioning. Some units can transfer moisture from one air stream to the other in addition to heat energy.

Air to air heat exchangers are used most often in large-scale commercial and industrial settings, where codes require large amounts of fresh make-up air be introduced to the building for the health of employees in the building.

III Equipment Options
There are three major types of air to air heat exchangers. Polymer fixed-plate energy recovery units are built around a monolithic heat exchanger that does not allow any cross contamination. Enthalpy wheel units are built around a slowly-rotating wheel that absorbs energy and moisture in one air stream and releases it to the other. Fixed-plate enthalpy units can provide up to 50% moisture transfer and additional thermal energy transfer.

While both enthalpy units have the potential for cross contamination, fixed-plate units have less than wheel or other moving enthalpy units.

IV Resources
1. Equipment Manufacturer Database
2. Natural Gas Efficiency Consortium