The working principle of Counterflow ERV cores is that two air streams flow parallel to one another, which provides the highest sensible and latent effectiveness for residential and light commercial markets. Produced with Fortunewayâs own patented polymer membrane, our ERV core has following features: high enthalpy efficiency; low pressure drop; high air tightness; water vapor permeable, can block VOCâs, CO2, NH3, and other gases & contaminants; can work under the extreme cold weather (-20â~-25â); service life can reach 10 years; anti-mold and anti-bacterial; can be washed by water, etc..