I divide a obligation for 36,000 BTU furnace for the downstairs. What happen if I use one near double the BTU? separate furnace and ducts for upstairs.

separate furnace and ducts for upstairs.
Convert a six panel pine door to one...
Answers:    Short run cycles.
Rarely operates at its rate steady state efficiency.
Possible short existence for the heat exchanger.
More than possible too small of duct work for the furnace.
Not a very consistent room warmth.
I guess your getting a good matter on it.
Then it wont be so bad if you own to replace it in a year or two.
Will a commonplace humidifier cool a room?
stop asking silly question and go to the professionals,. budge to a dealer that sell the equipment and they will advise you what the best course to approach this situation. they have adjectives the knowledge and equipment you inevitability. their interest is selling you the right stuff you need.
Hole within the wall?