Making an indoor forced air woodburner into an outdoor one

Propane just about killed me last year to heat the house here in Michigan. I'm seeing indoor woodburners on Craigslist for $500 (used), and outdoor used ones for $3000. Does anyone know where I could find plans or just plain old ideas on how to house and insulate the burner for forced air? I want to make one for the house and the other for the shop.

Neighbor has a outside forced air woodburner setup, until it blew sparks and flames thru ductwork to the house. Now has neither!

I've heard they are very dangerous. You may want to consider a boiler instead of the forced air unit. You can connect the boiler to your current forced air system and it will work well. New boilers start around $4,000 but used ones do come up from time to time. I just sold my 9 year old one for $900 to buy a bigger one.

Before you get into this very far, you'd be wise to check with your insurance agent. It's possible that the propane would be cheaper than the insurance, or lack thereof.

I'm told that 50 feet is the minimum distance that you can have an outdoor wood furnace, per some insurance regulations. Your agent can tell you if that is true with his company. 50 feet is pretty far to push hot air, but it's do-able with a boiler.

My BIL built a shed a few feet from his house and put in a forced air furnace. He's been using it for over 20 years with no problems. I read on here the horror stories and I guess there could be a problem. I just can't see how sparks or flame get into your duct work unless you do something really stupid or don't inspect your furnace every year. I've been burning wood for all my life and started out with a home made stove, moved up to a inside forced air and now have an outside wood boiler. I know it's in short supply now days but using common sense is always necessary .

After you look at the ones already built ready to use and the size of the doors you might just as well just look for a new one ready to go. It will pay for it's self in a year or 2 if you use that much propane.
If you have to buy the wood it won't save you that much.

That's how I heat my house. I took an indoor hot-air wood furnace and mounted it 30 feet from the house. But - built an insulated room around it and attached it to the house. So I never have to go outside to load the furnace. I can also store 3 full cords of wood inside where it gets warm and dry from the furnace. I can also clean the chimney from inside. I piped the hot-air heat into the house with insulated flexible duct-work.

I stayed this winter in northern Michigan (Alpena) and for the first time in over 30 years - I had to live with propane heat. NEVER again. If we use that house again this winter - I'm putting in a wood-furnace. What I do NOT want is an outside furnace that will not work without electricity. With the new emissions laws coming out - I curious to see what kind of price jumps all the wood burners take - inside and outside.

One thing that hurts when in Michigan is . . all my forest is cedar and poplar. No wood worth cutting and burning. I'm used to having my own wood in NY with 100 acres of hardwoods. Not free I guess when you factor in taxes. I just bought a load of 8 pulp cords of maple and ash in Alpena for $750. It irks me to pay money for wood - but it beats thousands on propane.

Anybody that has "sparks and flames" in their hot air ducts has problems I doubt can be blamed on firewood. If this was a common danger - every hot-air furnace that runs on propane, natural gas, oil, and wood would be banned.

Such "sparks" in a hot-air duct would mean a burnt-out heat-exchanger. If someone runs a furnace like that I'd say the problem is the idiot using it and not the type of furnace being used. If I DID have a heat-exchange fail - I'd rather it be with wood heat instead of fumes from an oil-furnace.

I've lived with forced hot-air systems for 50 years. Oil, propane, NG, and wood. Haven't seen any sparkts yet - at least not from the heat ducts. Chimney, yes.

I have been working on this project since early last October. I could care less what my insurance company has to say....I built it, and do it again if I have too...
It will heat my house, old garage and this one too!
I am not insurance POOR!

Most that you are seeing are indoor "add ons" made only to supplement the regular furnace. They won't last heating whole house all the time. Ask my son. His $ 500 used ad on lasted 2 1/2 yrs outside in an enclosure before it overheated and the coating melted off the wiring and started a fire in the enclosure. He now has a very nice factory built outdoor forced air ( $ 3500) and has it 35' from house,works beautiful and nothing to overheat and/or burn. Lot simpler and cheaper and more carefree than a boiler IMO. SIL has boiler right next door to this one and I will vote forced air. Get a new one and you won't be sorry.

I burn a lot of poplar. It takes more than oak, but it is good and dry and heats good.