Too many variables here. At what outside temp? How is furnace sized to load? What type of furnace? The fact is condensing furnaces (high eff mdls) would take longer than non-condensing 80% eff mdls.

not trying to dodge your question.

IMO

Let's say that the outside, and inside, temperature is 60, and I want to turn on the furnace and warm up the house to 70.

As I said, properly sized, not over.

Simple 80% downdraft furnace in a closet, unheated attic return, unheated crawlspace supply ducts.

Yes, I know there are lots of variables, which would certainly include the thermal mass of the building, and would certainly increase for colder temperatures, but I'm just looking for what would be considered acceptable for most.

The present system is adequate on the coldest nights, but barely so if it is also windy. I'm improving that with infiltration, insulation and duct work. The performance matches pretty well with my load calculations.

Thanks,
Gary

attofared

as quick as 15-30 minutes. supply temp should be at least 110 degrees.

IMO

Seems like an easy calc to make based on sq footage and furnace size. I was doing some math and my basement would heat up 10 degrees in about 10 minutes but that was probably 2x oversized.