[stevej37]

I am no expert on this subject...but I had a similar problem last year with my 25 yo Heil furnace.
The tech came out and tested it and said it was time to upgrade...a few problems plus the heat exchanger was slightly leaking.
He took one look at my cold air intake and said he would fix the convoluted mess of ducting that passed around a couple floor joists.
When done...the new two stage Heil runs at about half the noise of the old and my heating bill is way down. I should have had it looked at years ago.