# The Furnace Works SFB-3 Indoor Wood Boiler



## MotoBoyMatt (Jan 16, 2010)

I'm toying with the idea of buying this boiler used.

https://www.hearth.com/econtent/index.php/wiki/Furnace_Works_Boiler


I already have a Napoleon 1400 in the living room which provides 90+% of our heat.

I like the idea of having this in the basement and the possibilities of radiant floor heat for the cooler parts of the house,
energy storage, heating the garage remotely, etc.

Anybody have any experience with this model?

Any general thoughts?


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## pybyr (Jan 16, 2010)

MotoBoyMatt said:
			
		

> I'm toying with the idea of buying this boiler used.
> 
> https://www.hearth.com/econtent/index.php/wiki/Furnace_Works_Boiler
> 
> ...



I'm not familiar with the unit, but looked at the literature; it looks very low-tech, which means that there's not much to go wrong, but I expect that it will be _very_ hungry for wood per unit heat output compared to most things made since.  The metal gauge thickness of the boiler walls sounds rather thin, so if it was not cared for, it could be prone to corrosion issues.  If it appears to be in really good shape and is at a really low price, and you're an experimenter/ DIY-er, then it might be a good launching point for you.


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## Space Cadet (Jan 16, 2010)

I actually have one of these that has been in use for quite some time.  As mentioned above, it is very low-tech, but not stone-age.

The size of the metal doesn't really concern me, it looks much thicker in person.  

Mine is at least 25 years old, was outside (in use, exposed to the elements) for at least 4 of those years, and while showing her age, is still perfectly functional.  It has since been moved into the (detached) garage, where it heats a 24x24 work shop (walls insulated but no ceiling, 2 garage doors), and a 24x14 apartment / guest area.  I did have to replace the damper control motor (replaced it with a BELIMO from ebay).  It came second hand to me with a Honeywell aqua-stat installed to control a set of relays, which controls the burner, pump, furnace blower motor, etc.

I have added firebrick & a grate inside, and an external flue-gas heat exchanger in the style of a 55 gallon drum with some baffles (a lot of heat goes up the stack. it's easy to get flu temps over 1000*  within 18" of the outlet without even trying).  It smokes quite a bit when it cycles, but with the firebrick, it is much better once it gets heated up.  Once it has burned for about 5-10 minutes, the smoke dissipates to near-zero.  I'm working on an arduino control system at the moment, just got the sensors yesterday.  I've also acquired some (rock-wool?) insulation to wrap the girl in so she can stay warm...

I refer to it as a highly polished turd...lol.. but it's not so bad.  The whole system (about 30' one-way of 1" copper to an 80KBTU HX) holds approx. 15 gallons of water @ 12psi.  With a full load of good oak, on a 10-15* night, I typically get about 6-7 hours burn time with the thermostat set at 67.  It keeps both sides of the garage toasty warm, even though the thermostat is in the insulated apartment (the barrel heat exchanger made a huge difference in the workshop).  I do wish it had a larger firebox, but for what it is, I have got it working pretty darn well.

One good thing that has come from it - I found this forum, and have been occupied for the last 3 years now reading, revising, and otherwise tinkering with this darned thing.  It has been a lot of fun to piece it together and take it apart 3 times a year, making improvements...lol.

If you can get it for around $500 or less it seems like a good deal to me.  Just be ready to do a little tinkering...  If you want to see pics of my Frankenstein, pm me your email addy.


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## MotoBoyMatt (Jan 16, 2010)

The guy is asking $400 and I figured if I could get if for 250-300 it would be a fun cheap little project.

I'm a mechanical test engineer so having something to tinker with is almost mandatory.


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## rwh442 (Jan 16, 2010)

Matt,

For a couple hundred bucks - buy that beast and experiment away.  After that experience you'll know what kind of "new toy" to buy.  Gets you real world wood consumption numbers, storage estimates etc for future install.


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## MotoBoyMatt (Jan 17, 2010)

Apparently I wasn't the only one who wanted to experiment with this.  
It was sold for the asking price before I was able to arrange a time to look at it today.
Oh well, it was probably too big for my spot anyways.
My next thought is putting a Vogelzang Durango in(after the tax credit it would cost about the same as the used boiler).  I know it will fit because I did all the research before I installed my Napoleon in the living room 2 years ago.  The spot where I would put the durango in is on the other side of the house from the napoleon so it should help keep that area from being so cold.  I might put a "hotrod" or "hottube" style water heater in it, if for nothing else reducing natural gas used for heating domestic hot water.

Any body have any experience with these types of heaters?  
I think Daka and Yukon each make one. 
Anybody know of other models?


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## pybyr (Jan 17, 2010)

You didn't lose out on anything irreplaceable.  I do not know that model of Vogelzang, but in my personal opinion, a lot of their stuff is rubbish in regard to both efficiency and longevity.  

Keep an eye out and you are rather likely to find other 'previous generation' wood boilers around for only a few hundred dollars.


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## MotoBoyMatt (Jan 21, 2010)

I know, I know, the 'V' word.  As far as efficiency the Durango is EPA certified and even allowed in Washington State.  Are EPA ratings self enforced and meaningless?  As far as longevity if a $650 Vogelzang lasts half as long as my $1400 Napoleon I'm money ahead in more ways than one.  I think all the Vogelzang stuff is built in China which I'm not too thrilled about.  But then again what's not made in China these days?


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## pybyr (Jan 21, 2010)

MotoBoyMatt said:
			
		

> I know, I know, the 'V' word.  As far as efficiency the Durango is EPA certified and even allowed in Washington State.  Are EPA ratings self enforced and meaningless?  As far as longevity if a $650 Vogelzang lasts half as long as my $1400 Napoleon I'm money ahead in more ways than one.  I think all the Vogelzang stuff is built in China which I'm not too thrilled about.  But then again what's not made in China these days?


My boiler was made in Northwestern NY State; I like to support domestic manufacturing any time I can; in this case, the design and build quality is also excellent.


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## WoodNotOil (Jan 21, 2010)

Space Cadet said:
			
		

> I'm working on an arduino control system at the moment, just got the sensors yesterday.



Just wanted to make sure you had seen my arduino controller project for reference on your own.  It is now at both my new and old sites, plus there are posts on the arduino forum about it.

Sounds like a fun tinckering project.  You might even try experimenting with heat storage using an old domestic hot water tank or something.  Sounds like the water volume is rather small inside the unit and that would increase it a bit and possibly allow it to cycle on and off less.  You could control it from the arduino and all you might actually need to invest is in a pump.  Good luck tinckering!


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## Space Cadet (Jan 21, 2010)

It has been a lot of fun.  In fact, I did see your arduino project.  Actually, I borrowed some of your code.  

I just finished it last night, seems to be working great so far.
Has boiler damper/burner control with outdoor reset
Has apartment temp control with outdoor reset
has boiler over/under temp protection

I am still planning to implement a webserver, freeze protection, and automatic setback based on time of day for the apartment temp.

I also have 2x275 Gallon tanks insulated, buried & plumbed in the back yard to play with, just need heat exchangers.

Here is a link to my code: http://piintheeye.com/code/  Critique it if you don't mind and let me know if you have any ideas about how to improve it.

Thanks!


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## WoodNotOil (Jan 21, 2010)

My coding abilities for the arduino are rudimentary at best.  I do exactly what you did and borrow code from some other applications and modify it to my own.  I don't get erratic readings, but then again my application is way less complex.  My purpose in posting it was to give others a jumping off point, which it did in your case.  I am glad it helped you get started.

I would love to put up an article on your project.  If you are interested, send me a short write up and pictures and I will post it on my site with the code.  I want to get as many resources out there to inspire others to experiment.  That seems to be half the fun of this stuff at least!!


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## Space Cadet (Jan 21, 2010)

I will do that.  I had actually planned on making a couple web pages about the whole project myself, so when I get that completed I will send it to you as well.

Your code was an excellent starting point. In fact, it would have taken me much,  MUCH longer had it not been for the examples published on the web.  I do a lot of computer work, and specialize in board level electronics design/repair/etc, but I haven't wrote C since college, and even then I didn't pay much attention.  

If anybody can use it, tweak it, etc, go for it.  I hope it helps!


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## webbie (Mar 19, 2014)

https://www.hearth.com/talk/wiki/furnace-works-boiler/

Wasn't a bad little boiler - had water all around it, which is more than you could say for most.


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