Ducting.. for the Alaska 140

Ok so ive talked to a few people about setting this thing up. Ive got two answers: One. Duct the cold air side of the 140 to the Hot air side of my Natural gas forced air system. Then duct the Hot air side of the 140 to the cold air of the natural gas unit. Then run a thermal couple in the hot air side of the 140 to control the fan of my Nat. gas unit.

Answer Two: Share the cold air returns and share the main heat ducts. but i would have to block one of the units off so it dosnt create a loop with in the two stoves.

Dose any body have any advice on this? Please help.

I've never seen a coal furnace like yours, but Ill tell you how I installed mine. I had 2 blowers on the back of my wood/coal furnace. I removed them. I took the air from the gas furnace plenum and put it into the wood/furnace where the blowers were. Then ducted into the main heat trunk from the wood furnace. When the Control limit hits a certain temp in the wood furnace it triggers the gas furnace blower to kick on. When the gas furnace kicks on, it just helps the wood furnace heat. Its series installation. If the fire goes out, the gas furnace automatically kicks on. By installing them in series, you use the return for the whole house, and the heat gets distributed better, Before the heat from the wood coal furnace was ducted in the plenum of the gas furnace, the house was hard to heat. It sounds complicating but if you have any questions Ill glady try to answer them.

So with that set up your not using the blowers from the new fernace? I would like to use both if i can. Ive found some examples with the use of some baffle's or a back draft damper. Also were are is your cold air coming from? Thanks for the help.

I removed the blowers. I have 1 blower on the whole system, the gas furnace blower. I dont have a single baffle, because the air cant go backwards with this system. Currently on the system, I have 2 returns on the main floor with 5 supplys, and on the second story I have 4 returns and 4 supplys. I ducted the whole system in the house specially for the wood/coal furnace. There are 2 types of setups, Parallel and series. With both systems using the blowers, its parallel. The reason why I chose series, was lets say the coal furnace blowers are running, and the plenum on the gas furnace gets really hot, the gas furnace will kick on. So you had nice hot air with the coal, guess what the furnace blower kicks on and cools that nice hot air instantly. Plus you have to deal with baffles and such. I researched the series installation for quite some time and found thats its the only legal way in canada to hook a wood furnace to ductwork. I live in ohio but thought sounds good. Basically what it boils down to is the wood/coal furnace is one huge heat exchanger for the furnace. My wood/coal furnace is set to kick on at 150 degrees, and off at 85 degrees. This way the only air that comes from the system is warm air.
The only downfall I have found (But never had any problems with it is) If the gas furnace shuts down because through the night, the furnace misfires, then the blower doesnt work, therefore the wood/coal furnace overheats. Either way you have to consider an airspace in the ductwork to the floor joists incase of an overheat. I cant figure out how to shrink my pic to post it on here.