I am trying to install an off-air antenna in my attic. The only way I can easily get a coax cable from the attic to my basement is through the heat duct.

The cable would come into the basement through the heat duct about 4 feet from the furnace. So the duct is very hot. (I can probably exit the cable through the duct a bit higher up where it is slightly cooler.)

Is it an advisable method of running coax cable? I have heard suggestions that I should not do this period. Other suggestions are that it is OK as long as I use plenum rated coax. Still other suggestions are that regular coax is fine. Any ideas?

Thanks.