Why are two flaps better that one? Less resistance, maybe. Less squirrel traffic?
Venting into the attic turns your insulation into a conductor. Mold too. I was up in my attic to change out my plastic corgatted chepo duct with an insulated type. Then I realized I may be able to crawl in but never crawl back out. Like a lobster. My son will be 12 soon, I'll just grab his feet when he's done.
Why is cooking inside with gas OK to do but dont vent your gas cloths dryer into the house?
