Face Velocity Defined

Face velocity is the airflow divided by the core face area. It sets both effectiveness and pressure drop.

The Trade-off

• Low velocity - high effectiveness, low pressure drop, but a larger (costlier) core
• High velocity - compact core, but lower effectiveness and higher fan energy

Typical Bands

Plate cores often run 1.5 to 3.0 m/s; rotary wheels similar; heat pipes a bit lower. The optimum is where net energy saving peaks.

How to Pick

Start from the manufacturer's recommended band, then check effectiveness and pressure drop at your actual flow. Avoid the top of the band unless space forces it.