On Wednesday, January 27, 2016 at 8:06:27 AM UTC-5, Arnie Goetchius wrote:


My question: Is closing the ducts to three unused bedrooms and an unused
bathroom a bad idea and it won't save any money on the gas bill?

I didn't read this carefully enough the first time.

You have a furnace and gas heat. There might be places where a split system can heat for cheaper than gas, but not where I am nor any place I've lived.

I now see why you have more returns than I expected.

Yes, closing the ducts will save you money even if you don't block the returns. I'm assuming you close the door to those rooms. With no supply going into closed rooms, there's no pressure driving air into the returns. There probably is slight vacuum in those return ducts but they're sucking on a closed room, and there are lots of other return ducts getting plenty of air.. You could check this with a little smoke, I bet you'd find the returns in the rooms you are using draw much more air.