[Speedbird]

I am adding whole house fans and to reduce the noise I am ducting the air from the intake register to the 2 fans 15' away in the attic. I intend to connect the intake register to the fans via 2 x 14" flexible duct. I need to make 2 x 45 deg turns on each fan. Airflow is 1600 cfm/fan. Is this going to reduce my airflow in any significant way?. Obviously I want max airflow.

Thanks to the group.

 

[beenthere]

Might want to check, what static pressure the fans are able to work against.

Will each fan have its own back draft damper. They each need their own.

 

[Yoyizit]

Don't have the fan so large that it steals combustion air from gas-burning appliances in your house.