# I Built a Forced Air Outdoor Stove



## nealfire (Jan 26, 2012)

So after about two months of use, I am rather pleased with my outdoor forced air furnace project. I would have rather went with a better stove, but $$$ was a real issue. So instead, I purchased a discounted US Stove 1557 and dug in. I did find that the stove doesn't have enough push with the blower motors to satisfy me, so I purchased a booster fan and placed it inline. Seems to have solved the issue well. It is wired to the blower, so it comes on as the blower comes on. 

There is NO DOUBT that the wood boilers out there are MUCH more efficient than a forced air stove. But again, I have a FRACTION of money invested in this. Most of the parts to build the framing were scavenged from our farm. 

On a cold day (highs around 20f) I can load it in the AM, once again around 5pm, and top it off at bedtime (I burn coal with wood when it's really cold). At 7am there are still coals. I open the draft, and load it up again for the day. I am loving my power bill :msp_biggrin:

I did however get quite a bit of creosote (as seen in the video) from burning green wood and keeping the draft cut off too much on a warm day. Since then, the stove has done much better by keeping dry wood in the stove.

Here is a video of the stove

Building an Outdoor Wood Furnace - YouTube


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## Jakers (Jan 27, 2012)

looks good. should work well for you for many years. altho when you said you built your own stove i was thinking started from scratch and "built" the whole thing. i did that once myself. i modified a 265 gal fuel oil barrel into a huge wood stove. fun project but it didnt work very well.


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## nealfire (Jan 27, 2012)

Yeah, not from scratch. I guess I should have used the title "My Indoor Forced Air Furncace is Now Outside." Or something like that. 

I thought about building something from scratch, but I became quite intimidated. I did however look for used furnaces in my area, couldn't find any, but I guess that's just the way it is in November. 

As a side note, I am getting some heat loss from the front door, I haven't insulated it. I will also say that I am not impressed with the blower on the 1557, or with just about any of it. I discovered yesterday that one of the connectors that connect the two grates together has broken. I have kept ashes empty and haven't overfired it, not sure what happened here? Either way, US Stove will replace it, I called today. The problem is I have to get the serial number off of a plate that is located on the top of the stove. :bang: I Should have written it down in the back of the owners manual in the place they printed for it.


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## dave_dj1 (Jan 27, 2012)

I like it for the most part. What I did on mine (see thread here, http://www.arboristsite.com/firewood-heating-wood-burning-equipment/154832.htm).
Is your hot side (top tube) pinched off? It looks like it could be where it comes out of furnace.
It almost seems like you have it backwards, hot air wants to rise and cooler air is lower. (unless I'm reading it wrong).
I insulated my stove pipe too, I have a 7" inside a 10", it helps to keep creosote from forming.


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## zogger (Jan 27, 2012)

Nice video man and nice home made rig!


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## nealfire (Jan 27, 2012)

dave_dj1 said:


> I like it for the most part. What I did on mine (see thread here, http://www.arboristsite.com/firewood-heating-wood-burning-equipment/154832.htm).
> Is your hot side (top tube) pinched off? It looks like it could be where it comes out of furnace.
> It almost seems like you have it backwards, hot air wants to rise and cooler air is lower. (unless I'm reading it wrong).
> I insulated my stove pipe too, I have a 7" inside a 10", it helps to keep creosote from forming.



That's a great idea for the creosote, does it work well? 

The hot supply it is the solid galvanized type pipe wrapped with reflectex coming out of the side, I have to take it under the house to get into the HVAC ductwork so it can be distributed all over the house. The return made out of flexible line appears pinched a bit in the video (going into the bottom part under the smoke stack), it's not as bad as it appears, I actually went out to double check this evening. 

Another thing I would have liked would to have the stove more distant from the house. I was afraid the heatloss would be too great, and didn't want to spend the money on underground insulated pipe just yet. Sometimes when it's windy, a little bit of smoke works into the house, but most of the time it's just fine.


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## fun175 (Jan 28, 2012)

*my converted furnace*





i did the same with an old energy-mate furnace.
wrapped the furnace with 2x4 steel studs..insulated
with unfaced r-13 fiberglass..covered with sheetmetal!
ive since insul. the heat ducts..cost to build.....$100.
doing probly' 95% of my heat load!


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## owbguy (Jan 28, 2012)

what is the total out of pocket cost?


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## fun175 (Jan 28, 2012)

*my converted furnace*

i converted a Energy-mate furnace by wrapping with 2x4 sheetmetal studs..
insulated with r13 unfaced fiberglass..and covered with sheetmetal.
old furnace was free..got about $100 in conversion! its supplying probly'
95% of my heat in a 1500s.f. ranch. forced air goes to 2 floor registers.
cold air from opposite end of house.


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## chowdozer (Jan 28, 2012)

The way your pipes are stained, it looks like your pipe joints may be upside down. The pictures are not close enough I can tell for sure. Stovepipe joints should be oriented so the upper pipe fits inside the lower pipe during assembly (not the lower pipe inside the upper pipe).


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## nealfire (Jan 28, 2012)

chowdozer said:


> The way your pipes are stained, it looks like your pipe joints may be upside down. The pictures are not close enough I can tell for sure. Stovepipe joints should be oriented so the upper pipe fits inside the lower pipe during assembly (not the lower pipe inside the upper pipe).



I guess I do have them upside down then. I just started putting them together in order, IE Male end of pipe went into stove outlet, therefore it is upside down the whole way up now...ooops. Thanks for the heads up


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## chowdozer (Jan 28, 2012)

nealfire said:


> I guess I do have them upside down then. I just started putting them together in order, IE Male end of pipe went into stove outlet, therefore it is upside down the whole way up now...ooops. Thanks for the heads up



Since you're outside, I wouldn't worry about it too much unless you get buildup that could be a fire hazard, or puddling on your slab. (Or your wifey complains of "ugly"!!!)

I can't see from your picture, but I'll mention anyway. Always use rivets when assembling stovepipe. Sheetmetal screws always loosen with the expansion/contraction of the pipe. Rivets allow the joint to slide a little but still stay fastened together.


Many years ago, I put stainless pipe in my chimney. Stainless is a bit more pricey but has some benefits. It never corrodes, it takes a higher heat than steel or galvanized, and it holds it's shape well when it's hot. If you think you want a permanent installation, or at least as permanent as you live there, keep an eye on stainless pipe prices so you know what a good deal is, Craigslist etc.


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## Bushmans (Jan 28, 2012)

How far away from the house do you think you could put the burner? I saw a nice outdoor unit at TSC today for $2400. I just wouldn't want it so close to my house. I would love to have this instead of a woodburning insert in my fireplace.


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## dave_dj1 (Jan 28, 2012)

When I was researching to build mine I found that you can actually have pretty long runs as the air travels through them so fast that there isn't much time for any heat to be lost. The only draw back I see if they are too long is that you may get a burst of cool/cold air when the blower first kicks on. I think it's called the waterless stove? They sell an outside unit that is basically a barrel inside some tin work with very little insulation but on their site they have some pretty long duct runs. 
Maybe it wasn't that site but I have seen some when I google.


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## Bushmans (Jan 28, 2012)

dave_dj1 said:


> When I was researching to build mine I found that you can actually have pretty long runs as the air travels through them so fast that there isn't much time for any heat to be lost. The only draw back I see if they are too long is that you may get a burst of cool/cold air when the blower first kicks on. I think it's called the waterless stove? They sell an outside unit that is basically a barrel inside some tin work with very little insulation but on their site they have some pretty long duct runs.
> Maybe it wasn't that site but I have seen some when I google.



Here is a link to the one I was looking at. It must have been smaller because it wasn't 4Gs.
https://www.usstove.com/index.php?route=product/product&path=307&product_id=487


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## Wood Doctor (Jan 28, 2012)

Bushmans said:


> Here is a link to the one I was looking at. It must have been smaller because it wasn't 4Gs.
> https://www.usstove.com/index.php?route=product/product&path=307&product_id=487



Not to be the devil's adocate, but for $5 grand, you can buy a lot of natural gas or propane. Remember that these appliances are also hungry for wood fuel after you buy them. Are you committed to feeding one of them?


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## Bushmans (Jan 28, 2012)

Wood Doctor said:


> Not to be the devil's adocate, but for $5 grand, you can buy a lot of natural gas or propane. Remember that these appliances are also hungry for wood fuel after you buy them. Are you committed to feeding one of them?



I am currently subsidizing my heat with a fireplace. It has held the LP guys at bay for now but soon I will need a fill. $1500 a fill is a big ouch. Since July when I bought the house we have filled it once but that was the intro rate of $800 which put us at 80%. I have no problems with cutting wood and feeding the beast. My fireplace is the biggest beast you can find especially when you use it for heat.
I just want to find an alternate source of heat for my little 1800 sq ft bi level other than propane. I am tossing around and add on wood furnace, an outdoor wood furnace (not boiler) or a wood burning insert for my fireplace. Thank you for your concern by the way. I have no one around that heats with any of the above mentioned that I can pick their brains. Every one had OWBs.


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## howellhandmade (Jan 29, 2012)

Bushmans said:


> I am currently subsidizing my heat with a fireplace. It has held the LP guys at bay for now but soon I will need a fill. $1500 a fill is a big ouch. Since July when I bought the house we have filled it once but that was the intro rate of $800 which put us at 80%. I have no problems with cutting wood and feeding the beast. My fireplace is the biggest beast you can find especially when you use it for heat.
> I just want to find an alternate source of heat for my little 1800 sq ft bi level other than propane. I am tossing around and add on wood furnace, an outdoor wood furnace (not boiler) or a wood burning insert for my fireplace. Thank you for your concern by the way. I have no one around that heats with any of the above mentioned that I can pick their brains. Every one had OWBs.



When I installed a Napoleon 1100 in the fireplace of my 2500 sq. ft. two-story colonial, I didn't really have heating in mind. We wanted to use the fireplace, but the previous owners had had a chimney fire, so a SS liner and insert was way cheaper than re-lining the chimney. Very pleased, the insert cut our heat bills by around two-thirds.


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## nealfire (Jan 29, 2012)

Bushmans said:


> Here is a link to the one I was looking at. It must have been smaller because it wasn't 4Gs.
> https://www.usstove.com/index.php?route=product/product&path=307&product_id=487



I could be wrong, but I think it is the same stove that even Northern Tool carried for much less. Northern Tool used to carry that stove (maybe still) I almost bought it. Looking back, it probably would have been worth it to spend the extra money to just HAVE the stove ready to go. Not $4 grand worth it, but the $2399 I saw it for on sale.


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## Bushmans (Jan 30, 2012)

nealfire said:


> I could be wrong, but I think it is the same stove that even Northern Tool carried for much less. Northern Tool used to carry that stove (maybe still) I almost bought it. Looking back, it probably would have been worth it to spend the extra money to just HAVE the stove ready to go. Not $4 grand worth it, but the $2399 I saw it for on sale.




That was about what I saw it for. It was less than the insert I was looking at so it got my cogs turning. My biggest drawback is I don't want to have to run a chimney up and over my bi-level. 
My house is two stories for the main part and a one story garage. I don't know how I would achieve the correct draft placing it close to the house without the long chimney. I may be a loser all the way with the outdoor thing. Perhaps I should just let that one go and start looking at a used insert to try. 
Thanks for all the advice.


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## nealfire (Mar 9, 2012)

Just wanted to update you guys on how the stove performed over the winter overall. It worked pretty darn well, I still remain disappointed in the fan output. I am considering upgrading the blower this summer. The stove knocked about $640 off my total heating bill this winter

I ended up burning lots of in the stove in February during some cold snaps. The fire burned all night and then some with it. I've been burning coal from a seam that has been tested as one of the hottest burning seams in the world...so protecting the stove from getting overfired took some work. We've been using the heatpump the last 2 days since we've been in the 60's in the day and 40's at night, and the family already misses the super warm heat we've grown to love.


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## Felman (Mar 9, 2012)

You need a "heat dump" from the upper duct in case the power goes out? So the furnace doesn't overheat.


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## nealfire (Mar 10, 2012)

Felman said:


> You need a "heat dump" from the upper duct in case the power goes out? So the furnace doesn't overheat.



Yes, that would be nice. Not sure how to go about making it though for this stove though.


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## Felman (Mar 10, 2012)

nealfire said:


> Yes, that would be nice. Not sure how to go about making it though for this stove though.


Heat dump would be a fusible link that melted when the temp got too high & possibly overheat/warp the furnace. Foremost, I think you'll have to replace the elbow with a tee & figure out how to get the top of the tee to open when furnace overheats.


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