Re: duct work for furnance
The problem is more likely to be the blower in the furnace. It may be out of balance or need to be cleaned. The blower should be installed with rubber "shock mounts" to isolate vibrations; these mounts may have deteriorated and need to be replaced.
The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.