Brad,
I am no expert or even a think I know what Im doing guy when it comes to this stuff..LOL I can tell you how ours works. The wood furnace sits next to the LPgas furnace/Central Air unit.
The cold air returns go to the gas furnace, then right after it exits the fan, goes into the warm air ductwork. There is a couple of air diverter gates, (don't know proper terms for them) that you turn when your going to use the wood furnace. They direct the air down and into the wood furnace, and exit the top of the wood furnace directly back to the warm air duct work.
This old house is approx. 1300 sq.ft. We have added new windows, doors, over the years, with some blown in isulation. There was absolutely none before.
Two story, with small rooms upstairs. Only one heat vent going up there. In the basement, cellar is better word, its unfinished, with a block wall and door to the wood/coal room. On the other side is small food/can good room. The rest is crawl space.
The wood furnace giving off some radiant heat, keeps it quite nice down there. No heat vents down there at all. Im sure your house will not be a problem. I usually put 3-4 chunks of wood in right before I go to bed, usually around 11-12:00pm. Usually get up anywhere from 5-7 am. The fan will be running, the temp dropped a couple degrees, but far from being cold.
I remove some ash, rake the hot coals around, add wood, and in a few minutes its cranking out heat again. I have the gas furnace set to come on if it drops more than 5 degrees, so far it hasn't come on at all, that I know of.
When the T-Stat calls for heat and fan kicks on, the auto draft damper on the wood furnace opens and the fire is burning. When it kicks off, the damper closes down, and knocks the fire down, so to speak. The fan on mine usually will come back on and run briefly, then stop. Then come back on briefly again. Does this several times, till the heat in the wood furnace has subsided sufficianty. By the preset on-off temp setting on the fire box enclosure.
Long story short, LOL
I don't see why you can't in some simple way, direct the airflow from your existing fan to pass through your new wood furnace. Theres obviously some technical issue I'm not grasping.
Seems to me a wood furnace would heat your house nicely, whether you use exisiting fan or add on blowers, either way.
Anyway, this has been an interesting thread to follow.
and will continue to follow.
Good luck with this adventure!!
Gregg,