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Sunday, October 14, 2012

Outdoor Wood Furnace

It's that time of year again! Every year about mid-October we fire up the wood furnace and it stays lit until April or so, depending on the weather. This will be our 5th winter with this stove, so we have plenty of experience with an outdoor wood furnace in case anyone is interested. I know what the advertising says and I know what the reality is. So let's get started!
Purchased in 2008, our wood furnace keeps us really warm!




Our stove is located about 75 feet from the house. In the house we use radiant floor heat, and also heat our domestic hot water through a small heat exchanger. Since our hot water is electric during the warm months, our electric bill actually goes down in the winter season. I can't say enough good things about radiant floor heating - it is the warmest and quietest heat we have ever had.

As far as the stove goes, I think they are all about the same. My model has a stainless fire box, but I wouldn't hesitate to have a carbon steel box either. Ours has forced (fan) draft. All of the forced draft models are very efficient burners of wood. This means you won't have many ashes left over and you can (but maybe shouldn't) burn almost any wood in them - green or seasoned. Our model is also well insulated and can hold hot water for several days if it isn't needed. 

However, I feel that the overall efficiency on any of these stoves is relatively low. The big reason is the wasted heat blowing out the stack when the burner is on. This wasted heat also includes lots of unburned wood gas. When my stove is blowing, I can hold a propane torch beside the exhaust stack and the smoke will burn with flames shooting as much as 10 feet in the air! With a cabinet or indoor stove, the air is supplied by the damper with no forced air and the wood slowly burns. A larger portion of the heat stays in the house and is released over a longer period of time.

Everyone is flabbergasted when I tell them that we typically burn 8 cords of wood each winter to heat a 2400 square foot house. Most of those folks have a small wood stove and some other source of heat. We heat with wood only - even our back up heat is a fireplace. If we don't take time to keep the fire, no propane furnace or kerosene heat will kick on to take up the slack. We buy most of our wood in log length and I still come out 2/3 cheaper than I did when we used to have an electric furnace. That is even with hiring most of our woodsplitting at times!

Anyway, Saturday was wood stacking day at Far Better Farmstead. Most of the wood was split in July and piled in the field where the logs were delivered.

Our wood hauler isn't large or 4x4 but we are thankful for it!
It took all day but we filled our wood shed, leaving enough room for the '54 Chevy to go safely back inside. The chicks are also brooding in the wood shed.
All back in place. I will start using this wood in earnest in January

The controls for our radiant floor and hot water exchanger. They look a little complicated, but are actually very simple. We have a thermostat for each floor of the house. The little headers have adjustments to balance the rooms. Our hot water heater exchanger is the little brick on the left.


In summary, here are the pros and cons of our outdoor wood heater:

Advantages:
1. Clean, no wood scraps and bark carried into the house
2. Efficient (at least it burns any and everything we throw in it with little ash left)
3. Comfort - this is the warmest heat we have ever had- even the bed is warm when we turn down the covers!
4. Cheaper than our old electric furnace by 2/3 even with purchased wood
5. Safe - the fire is 75 feet from the house 

Disadvantages:
1. Burns a lot of wood - we live in NC and burn about 8 cords per year (but that is a log house, every square inch plus hot water)
2. Requires a lot of attention - I visit it 3 times per day in coldest weather, my wife calls it my "girlfriend"
3. Wasted Wood - exhaust gases can be ignited most of the time, indicating lower efficiency burn
4. Cost - I forgot to mention that an outdoor furnace costs 4 or 5 times as much as an indoor wood heater

Overall we still feel the advantages outweigh the disadvantages and when this furnace wears out we will replace it. 

-Dad

12 comments:

  1. Interesting, I didn't know something like this even existed...

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    Replies
    1. Madge - Thanks for stopping by! These furnaces aren't that common but are gaining popularity. The firebox is surrounded by a water jacket, so the heat produced for the house is hot water. Some advertisers claim extreme efficiency but most folks know better (no such thing as a free lunch!)

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  2. It really saves much money on the firewood like you that have the own firewood, but I have to buy the wood for my log burning stove

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  3. Corrinla,

    You are correct in that efficiency doesn't matter as much to me since I have an unlimited supply of firewood just for the cutting. But it does cost time and effort to cut the wood (just not $$)! Thanks for stopping by.

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  4. I found this wonderful blog but I'm looking for the post of home heating repair Midlothian va. Thanks!

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  5. Have you ever considered burning coal?

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    Replies
    1. Steve,
      Coal would be great if I could find it here in quantity. The local coal company went out of business. I do have 30+ acres of forest and that makes wood pretty much sustainable for me if I manage it properly. Of course when we get old enough - we may have to resort to things easier on our backs!

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  6. Where do you buy your wood? I live in Rutherfordton, NC and having trouble finding a logger who can deliver. I also have a Heatmaster SS. Thanks, Lee

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    Replies
    1. Lee,
      Thanks for stopping by. We live above Rosman and usually get our wood from a cousin of mine in Jackson County. He does grade work and usually has a bunch. In the last few years it's been drying up because a lot less grade work is going on. That's why I got myself a 4x4 and started harvesting some from my own property.

      In "Ruffton" I'd check with grading contractors and tree services - those guys usually have some wood.

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  7. Thanks so much for sharing these tips. Even though it is starting to get warmer, I have contemplated getting an outdoor wood furnace because we had a difficult time staying warm this winter. I will definitely refer to your posting so I will know what do.

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  8. I have read your page. I found this post to be very informative and helpful. I will have to recommend you to my friends. Great wood outdoor stove for using our better place and pleasuring this blog me to cooking look forward...wood furnace Buy a Greenwood wood boiler that saves 70% on your home heating bills. We offer the world-class wood gasification heating appliances on an affordable budget. Thanks for your post.
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