I'm wondering if you agree the original installation fifteen years ago was screwed up? I can't imagine that the tapered thingy down to 10" dia. would be correct on a 14" return. The AC tech who is installing the new AC already told me to replace the 10" supply flex (after a tee" ...

Newbie here. What little I know here I have learned in the last few days on the internet. But I've worked in several shipyard trades and have some background and fair mechanical ability. I have a used doublewide and while replacing the air filter noticed something that may be a little out of order. ...