This tells us that, for max no-compromise performance, the engine wants about a 5-inchid single duct. If there's insufficient room for one big single duct, consider a dual-duct arrangement.

PART I Chapter 1 General Balancing Procedure Chapter 2 Preliminary Air Balancing Procedures Chapter 3 Air Balance Procedures Common to All Systems. Chapter 4 Balancing Constant Volume Low Pressure ...

The SDP2 standalone dual in-duct digital psychrometer measures both supply and return air conditions at the same time dynamically. All readings adjust automatically based on changing conditions.