DIY Furnace

[JayG]

So I want to build an outdoor furnace cheaply and use it for seconday house heating (1400 sq ft) . Rather than pay $6000 for new heat pump we have survived two winters with NG fireplace and couple electric heaters.
This will will primay heat . On days below 35 degrees I would like to use outdoor furnace. Oak firewood is free to cut and plentiful. I have questions.
1. Live in rural area are there ant EPA concers?
2. Do I need a fan to blow into existing duct work for 50ft?
3. If so what CFM should it be?
4. Barrel wood stove is $160. Will it heat up my 6x5 ft metal shed? See pic
5. Any gotchas on shed use?

I've had two strokes and I'm not as nimble at 55, so bear in mind.

 

[Tonty]

Whoa, do you have fire department on speed dial? 🤔
Others on here can give you specifics, but my seat-of-the-pants calculometer says you are going to have to get that shed quite hot to do any good ducting air into a house. Water is a much more efficient method of transferring heat.
Don’t waste your time trying to re-invent the wheel. Buy something (outside wood boiler) that will work. But that may not be worth it in Alabama, I don’t know.

 

[JayG]

The shed is entirely metal. I would think blowing the heated air into the house, with fan, would be enough. The shed would sit 20ft from house. Air would be recycled to draft the stove. What could catch fire?

 

[hedge wood]

JayG First welcome to the forum. The first of many problems with your DIY system is the supply of combustion air to your barrel. Take a look at Bryan outdoor wood furnace. I have seen a number of them hookup to trailers down south. New one is fairly high but I will bet you could find a used one. Years back there sere some around here but I think our climate is just too cold for them to work well.

 

[maple1]

Most of your wood heat potential will be going to the great outdoors. For starters.

What will stop your blower fan from pulling nasties from the firebox and putting them in your house? Potentially killing them while they sleep?

Forget this idea. If you have NG why not a NG furnace?

 

[brenndatomu]

Years back there sere some around here but I think our climate is just too cold for them to work well.

Same here...almost none around anymore as they just didn't work very well...heck I think the dealers even quit selling them. (and our winters aren't very cold here anymore, on average)
Trying to DIY one seems like an exercise in futility to me.

 

[salecker]

There is a guy local who has heated his house for 20 years with a similar setup.
He has a big wood stove that is below the level of his house,he has 2 big culverts going under his house from his outdoor stove. He has the culverts burried and an enclosure around the stove that is partially buried as well.The front of his stove is exposed to outside with a roof over it.
He said it's easier to move the cold air to the stove instead of moving the hot air.
I would look at a wood furnace to use. That barrel is not going to last long. New barrels are made from thin tin.Find an old barrel if you are going that route.

 

[Tonty]

Couple of stories. When I was 18 or 19, a local house burned down. I was on the FD and responded to the call. I won’t say everything I saw, but I won’t forget that call. It was a large family, and half of them died in the fire. There is some supposition here because the house was totally destroyed, but the “undetermined cause” could likely have been a barrel stove that was used for heat. Now I know that was in a house, so it’s a different deal, but I’ve looked at barrel stoves differently ever since.
Second story- in my boyhood home, our sole source of heat was a “Wonder Coal” stove that we burned wood in. Good old stove, put out a lot of heat. The chimney set up was, uhh, politely put- subpar. We had 3-4’ of triple wall pipe going through the wall, then a home built, single wall, steel pipe going up 25’ or so outside. Creosote city. We would have several chimney fires per year. I won’t forget that sight or sound, either. Fire and embers shooting out the top chimney. Roaring noise from inside. Garden house out wetting down the house roof. We never burned the house down, but I’m not sure why.
Now what would happen in your setup if the stove would “melt-down” due to a subpar barrel or any of multiple reasons Your “furnace fan” could very easily blow embers from that episode into your home. What would happen if you had a roaring chimney fire? 20’ from the house isn’t all that far.
Most likely none of this would happen. But please consider it before you build.

 

[salecker]

Barrel stoves heated most of rural Yukon for the first century of it's existence.
Just like any stove when used improperly there are bad consequences.
I still have one in my shop at home,but it's 1 1/2 times the size of a normal barrel.

 

[farmwithjunk]

Why not find a used Woodchuck in decent shape that is already setup to blow hot air and has auto draft/blower controls?

 

[Micdrew]

Any place to put in a wood stove or insert? Seems like a lot of trouble for secondary heat source and for Alabama weather…. My pastor has a free standing EPA stove in his house, I dropped a load of firewood off to him Christmas Eve morning and it was 7 degrees outside and his house was sitting at 72 same as my house and I have a kuuma vapor fire wood furnace.

 

[JayG]

Two things to consider:
1. Hardwood oak is all I will burn. Unlimited supply.
2. Really only burn when temp goes below 35 degrees. NG fireplace has worked well for three years.

Most of your wood heat potential will be going to the great outdoors.
Possibly. Can use the high temperature Insulation on the walls.
I've seen a couple of videos that measured the outside barrel temp at 650 degrees.

What will stop your blower fan from pulling nasties from the firebox and putting them in your house?
Should not be any more risk than other furnaces.

That barrel is not going to last long.
Prob right, but if I can get three years then replacing it for $160 bucks ain't bad.

Two questions I have now
What CFM would the fan have to push.
Would a woodstove fan hold up to that heat on the wires (internally)

Not trying to be confrontational guys and thanks for all the replies.