I have a 10-year-old Rheem 92% high-efficiency condensing gas furnace which has given outstanding service (especially after I fixed the condensate leaks, something the lazy factory should have done to begin with, but that's another story).

The only issue is, when the blower spools up, the 60Hz hum from the motor is really obnoxious. When it's up to speed it's fine. The motor is hard-mounted to the blower case, which turns the furnace and ducting into a nice 60Hz sound board. Any ideas on how to quiet this thing? Thanks in advance.