It sounds to us like you have two problems: a sloppy furnace installation and a sloppy furnace installation. As a matter of fact we can almost guarantee that the installer you hired would probably be better off doing gardening.

The initial shower of debris (aluminum shavings, insulation, etc.) indicates a mess left in the duct pipes and adjacent air distribution cans that can only result when the installer isn't careful about cleaning up during installation.

We feel that you should ask the contractor to come back to do a proper vacuuming of the ducting - at his expense. You didn't leave the mess - he did. He will have to remove all of the register covers and feed a commercial (high-powered) vacuum hose deep into the ducting to clean up the mess that was left. Doing the job properly might take two visits. One to get the heavy debris and a second trip to get what comes loose after the first cleaning.

It would also be wise for you to check the furnace filters. If they were installed incorrectly or if they have gotten dirty prematurely (as a result of the grubby ducting), then during operation, the furnace will constantly generate a thin layer of dust from one corner of the house to the other.

The same thin layer of dust will result when a filter is the wrong size, has been installed backwards or is a cheap brand. Make sure that the filter being used is recommended by the manufacturer of the furnace.

Next time - hire a different contractor. And don't recommend this one to your friends. In construction - a slob today is a slob tomorrow.