Thanks for your time, although I think it is a very bad idea to use nVidia for mining. It is just not effective - you burn more electrical power than you earn by mining BTC. One specific situation when this would be profitable is a free energy source (free for you, not in general).
Even then though, it'd better to buy a strong Radeon card and earn 10x more.
I think you're 100% right
And I'm paying for my electricity, so it'd be an expensive way to heat the room
I was thinking about it too. A few years ago, when electrical power was cheaper, I used electrical heater to warm my room in the winter. Now I wouldn't do that, but what is the difference between a simple heater and a complicated electronical device - both of them produce heat that you can use or discard. Efficiency is probably just a bit smaller for a GPU than for a heater.
So, mine some coins, feel warm;)