I'm installing my CV1800 in the attic over my garage, with 6" mains ducting. I'm thinking of using 8" insulated flex duct for the return to reduce noise in the return run. My concern is that specs for the insulated HVAC flex duct max out at 200 CFM. I'm concerned that over time the plastic liner will break down under the higher airflow of a DC. Any thoughts?
I'm OK with springing for spiral duct for the return, but I'm looking at about 20 linear feet with two or three 90 degree turns, and the 90 sweeps add up for spiral pipe and it will be noisier than flex duct, so I'd rather not spend that if I don't have to.
I'm OK with springing for spiral duct for the return, but I'm looking at about 20 linear feet with two or three 90 degree turns, and the 90 sweeps add up for spiral pipe and it will be noisier than flex duct, so I'd rather not spend that if I don't have to.