I removed an old coal furnace from my basement. The furnace did not have any duct work to speak of. There was an exhaust pipe which fed into the chimney and a duct that went into the next room, but for the most part all the heat went up through a 30" x 30" hole in the ceiling above it. The hole is covered by a floor grate without any filter or louvers.
My house is 1100 sqft and reasonably well insulated. Can I install a new gas furnace to use this same hole? Is there a particular type of furnace that would work best for this application? Do I need to worry about a cold air return? I'm assuming I would need to add some kind of filter. I would greatly appreciate any general advice on how to approach this project. Thanks in advance.