I have a 52' x 28' manufactured home sitting on a full basement in Grand Rapids, MI. Currently there is only one furnace upstairs (66,000 BTU) with no return ducting like a typical junkie manufactured home. I'm in the process of finishing off the basement into a downstairs apartment which will be completely separate from the upstairs.
I need to know the best solution for implementing a new furnace. I can either keep the old furnace upstairs and put a new one in just for the downstairs or a single furnace system to run the whole house. Of course with a single furnace I would use a zoning system to keep the first floor and basement comfortable temperatures. Also, what would be a recommendation on the proper BTU and CFM for heating a house of this size (both basement and first floor).
FYI: The local heating company thought it would be best to install a separate furnace in the basement. I can't find to quote for how many BTUs they recommended.