I don't think anyone will realistically use miner heat to warm up the house. I think a smarter solution would be to move mining equipment into a room or area where you can shut off the furnace vents or maybe even open up the windows and let in the cold winter air.
haha, you're missing the point! any money saved by heating your house with your rigs is now LOST to the outside! why not just... HEAT YOUR HOUSE with your rigs?
If the rigs are putting out too much heat however, you could have a distribution issue, and need fans (which cost power too). Better to spread the rigs around the house,
in drafty areas, say under windows
Still you are saving the cost of gas on that electricity only, still going to be 7-10c/kWh in most of the cheaper markets for heating by electricity, and still much more (tho in such markets,
gas tends to be more $ too - there's some friction between gas and electricity prices in each market).