Wood / coal furnace

Discussion in 'Back to Basics' started by oil pan 4, Dec 1, 2017.

  1. oil pan 4

    oil pan 4 Monkey+++

    Tractor supply has them on clearance apparently they have been on clearance for a while now.
    So I'm getting one.
    The big one was originally $1,100 the manager asked me if I was seriously thinking about getting one and said he could do 650.
    They carry a big one and a bigger one.
    The big one holds 50lb of coal, the bigger one holds 70lb.
    Normally I say bigger is better, but the bigger one uses 2 blower fans.
    The big one only uses a single fan.
    That means double the power for the bigger one.
    The fans are the same size, just that the bigger furnace uses 2.
    I guess normally these go outside.
    I want to put mine in the garage.
    Gator 45/70 and Motomom34 like this.
  2. ghrit

    ghrit Bad company Administrator Founding Member

    Love to look at it. Got a model number and a link?
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  3. azrancher

    azrancher Monkey +++

    Need to read what size area the big one, vs the bigger one will heat, you may not be able to utilize the "BIGGER" one, if you know what I mean... And you could always wire in a switch into the bigger one to only use one fan, or better yet use an alternating relay to switch between the 2 or use both for more heat during a really cold spell, contact me via PM I used to sell them on Ebay for $25.00, they are plug in, 8 pin socket type, made by SSAC (who has been owned by Enterlec, Potter Brumfield, and probably other during the past 25 years, but they make darn good relays, (digital timers, water level detector, phase detectors, and alternating relays).

    I bought a bunch, like the close out of an electrical store, so had at one time 100's of them. Also have some water level detectors left, I'll get the part numbers if you are interested.

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  4. oil pan 4

    oil pan 4 Monkey+++

    The bigger one can take about a 28 inch log, the other one will take about a 24 inch log and is also 4 inches narrower.

    I got to thinking after I posted this about running only one fan, maybe use a flapper.
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  5. oil pan 4

    oil pan 4 Monkey+++

    I'm getting the larger one, for 750.

    The tractor supply here does not normally carry coal but they said they will special order me some. I figured I might want to roll coll on the really cold nights or in the morning on a cold day before I go to work.
    Last edited: Dec 2, 2017
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  6. Motomom34

    Motomom34 Monkey+++

    Do you have a good supplier for coal? It think that would be the only draw back is the availability of coal.
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  7. oil pan 4

    oil pan 4 Monkey+++

    It can burn wood.
    It doesn't have to only burn coal.
    Last edited: Dec 4, 2017
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  8. oil pan 4

    oil pan 4 Monkey+++

    I' getting it put together finally. Been working a lot.
    I' not really seeing a good way to run 1 blower.

    I'm going to modify the factory electrical a little. Maybe a lot. They want the blowers hard wired with MC to a 1.5 deep 4x4 junction box.
    Running 120v power straight through the temp switch.
    What I want to do is hook it up to 240v power.
    Put a 120v cord on each bower. Plug each blower into a duplex receptacle with each receptacle wired L to N.
    Use the temp switch to power a hot swapable relay, so it lasts a lot longer.
    At some point put in an adjustable temp switch.
    When the relay goes bad i can yank out the bad on and stick in a new onw with out even turning off power. Then as a backup, to aid trouble shooting and to get heat out of it sooner put a spring wound count down timer.
    Then when the power goes out I can unplug the blowers and run them straight off 120v power.
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  9. duane

    duane Monkey+++

    Coal is getting harder and harder to find and there are all different types, qualities, and sulfur contents and it may not be legal to use in some "green" dominated areas. We heated with it as a kid in the 1940's for very cold nights, used wood the rest of the time, and I was told all sorts of horror stories about people dying in their bed from CO poisoning. It works well but a chimney, stove pipe or stove problem can be fatal and unlike wood, the smoke may be hard to detect. Fired furnaces at Lowery AFB in mid 1950's and the old barracks were all heated with coal, we had 16 buildings, and you were on for 4 hours as a replacement for KP and other duties. The coal was a soft coal that had been compressed into about 1 in pellets and burned very well but tended to form a very hard clinker if not attended to about once an hour. Fired the furnace from a wheelbarrow by hand and a full fill was about 75 lbs, but taking care of it with the least problems and work, we had the best luck firing about 25 pounds once an hour and making sure it was breathing right. Old rule used to be chunk anthracite with low sulfur for hand firing, some chunks would weigh 25 pounds, and pellets made from soft coal for an automatic stoker. The hatchery had a stoker that took about 600 pounds of pellets for a fill and had a ramp to take wheelbarrows full of coal up and dump into the feed hopper. That is a good price for a coal furnace, might find a more efficient wood burning furnace, but it would be pricey. While feeding the air from below through the grates works very well for coal, the lack of secondary air and burning the smoke above the fire before it goes out the chimney is somewhat of a limit in "banking" down a wood fire when you want either less heat or a longer burn time.
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  10. TnAndy

    TnAndy Senior Member Founding Member

    Had two of these in my shop....previous and current. They are OK, but what I found with the previous one is the firebrick doesn't come up high enough to protect the fairly thin gauge metal wall inside, and it burned out in 8-10 years....

    SO this one, before the first fire built, I field modified it.

    Took some 1/4" thick x1x1 angle (the angle holding the brick also burned thru in the first one....too thin), welded it to hold another row of fire brick above the side layer, which sits at about a 50-60 degree angle in this one. Also, mount the stove up on cinder block on each corner....makes loading/ash removal easier. NOW I have a furnace that should last a lifetime.
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  11. oil pan 4

    oil pan 4 Monkey+++

    Thank you I will do that too.

    I was going to put mine up off the floor on bricks, but will do blocks instead.
    Did you stack the additional fire brick tall ways or short ways?
    Do you think short ways would work?

    The coal furnace is going on in he garage and we have CO detectors.
    Last edited: Dec 16, 2017
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  12. TnAndy

    TnAndy Senior Member Founding Member

    They are installed vertically to match the ones below laying at an angle. The angle deal IS a design improvement over the previous model, which used a thin piece of angle to hold them in place vertical, since the angled ones don't have anything but gravity to hold them in place (if I recall correctly.....been a few years since I stuck my head in the stove...ahahaaa).
    I guess you could install them horizontal....it would help more than nothing, for sure, but heck, as long as you're going to the trouble of doing it, why not get more protection....brick are fairly cheap.

    I'm going down to work in the shop today, I'll try to get some pics.
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  13. TnAndy

    TnAndy Senior Member Founding Member

    OK. pics....
    Told you wrong on a couple things....the angle is 1 1/2" x 1 1/2" x 1/4"...not 1x1.

    Original brick below, at angle. Added above sitting on my angle.

    Top angle added to hold brick....note the notched out section so you can slide the brick in from front to back.


    And I put the stove up on an 8" block, plus a 4" cap block.....total of 12". And really, two full 8" block wouldn't hurt....keep from having to bend over to load, clean ashes. Of course, I'm loading wood....you'd be shoveling coal, so maybe NOT for your use. Note too the 2x2x12" stick standing on the loading lip....I use it to prop the 'flap' open to make loading easier....then set it on top the stove.


    A handy tool you might make yourself....short piece of 2" flat bar welded to a handle of rebar about 4' long. When you pull the ash tray out, some fall back behind it and builds up, not wanting to let the tray go all the way back in....reach in and pull that build up out with this tool. For coal, you'll need a poker too, to bust up the clinkers that form from coal, if I recall from my coal burning days as a kid.


    One final modification....I added a handle to the door, handle from something I had laying around....because the door gets HOT !! and this let's me open it without burning my fingers.

    Lastly, since I burn wood, I built a rolling basket 4'x4'x32" deep to hold my wood. I roll it to the front of the shop (stove is located back part of shop) where the roll up door is, pick up with the tractor forks, go to one of my sheds and load, then reverse process. I also burn my scraps from woodworking, which provides a lot of my fuel.
  14. oil pan 4

    oil pan 4 Monkey+++

    I will be mostly burning wood in there.
    Only shoveling coal on real cold nights.

    How noisy are the blowers?
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  15. TnAndy

    TnAndy Senior Member Founding Member

    not bad...but then the shop is pretty big, and I usually have something else making noise.
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  16. oil pan 4

    oil pan 4 Monkey+++

    The main thing I wanted for Christmas was coal and I couldn't even get that.
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  17. oil pan 4

    oil pan 4 Monkey+++

    Ok I have neglected my coal furnace project for way too long.
    I bought it last December, put it all together and just used it to keep dust off the floor.
    Well I finally test fired it out side, to burn all the oils and dust out of it.
    I just hot wired the blowers.

    I like it. It puts off so much heat. Even drawing in cool 50F outside air.

    Even tried out wood pellets. I got a good bed of coals going shoveled in some wood pellets, gave those a few minutes to start burning then shoveled in some more and wow that really got the fires burning.
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  18. chelloveck

    chelloveck Diabolus Causidicus

    You evidently weren't a bad enough boy! Only bad boys (and girls) get a lump of coal for Christmas. ;)
    [​IMG]Christmas Traditions- Coal for the bad kids

    Nice setup by the way. Positioning the standby fuel close to the furnace is good...ergonomically efficient and ensuring that the fuel is extra dry. Having the storage bin on casters is an excellent idea.(y)

    Perhaps making the storage bin into two bays might be a good idea....that way at the half way point (i.e. when one bay is empty, there will be half a bay of fuel still left, and the empty half can be refilled by wood from the bulk storage, and give it enough time to dry out before it becomes necessary to start using that bay. A small loss of storage space may be compensated for by other efficiencies.
    Last edited: Jan 7, 2019
  19. oil pan 4

    oil pan 4 Monkey+++

    I over fired the furnace for all its worth and I could still set my hand on the side with the blower going.
    Then Andy modified his with bricks more than half way up the side so its sides won't get as hot as an unmodified one.
    Gator 45/70 and chelloveck like this.
  20. oil pan 4

    oil pan 4 Monkey+++

    I like burning coal.
    If I could get a ton or 2 that would last all year. I could heat the house for less than $200 a year if I could get coal delivered.
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