what size coal to use

I have an old kalamazoo gravity furnace that I'm using as a wood burner outside but come maple sugarin' season I want to set an evaporator on top of it. It looks like a pot belly stove. It has a shaker grate that sits about 12" above the base where the air can be regulated from, then the "pot belly" of the unit can be filled with coal I imagine. Rice coal falls through the grate, what size should I get for maximum burn? I'll need to boil off a couple hundred gallons of sap so the hotter the better, and it's outside so in the event of a meltdown no big deal. The only thing I care about is getting the stove as hot as humanly possible.

If you don't have access to the owner's manual to tell you, I'd go with nut by the sounds of your setup. It'll give a nice long hot burn..............

e.alleg wrote:I have an old kalamazoo gravity furnace that I'm using as a wood burner outside but come maple sugarin' season I want to set an evaporator on top of it. It looks like a pot belly stove. It has a shaker grate that sits about 12" above the base where the air can be regulated from, then the "pot belly" of the unit can be filled with coal I imagine. Rice coal falls through the grate, what size should I get for maximum burn? I'll need to boil off a couple hundred gallons of sap so the hotter the better, and it's outside so in the event of a meltdown no big deal. The only thing I care about is getting the stove as hot as humanly possible.

Nut or Stove would be what you need
Nut will burn longer
Stove will burn hotter but Quicker

How wide are the slots in the grate?? Can you stick your finger or thumb through the slots?? if so Pea is too small, go with nut... I'd be wary about using stove.. It is hard to burn well in a small firepot... Nut will do much better...

As for 'as hot as possible', can't you burn the sap if the pan gets too hot on the bottom?? Especially as the water boils off, and the syrup thickens???

Greg L

e.alleg wrote:I have an old kalamazoo gravity furnace that I'm using as a wood burner outside but come maple sugarin' season I want to set an evaporator on top of it. It looks like a pot belly stove. It has a shaker grate that sits about 12" above the base where the air can be regulated from, then the "pot belly" of the unit can be filled with coal I imagine. Rice coal falls through the grate, what size should I get for maximum burn? I'll need to boil off a couple hundred gallons of sap so the hotter the better, and it's outside so in the event of a meltdown no big deal. The only thing I care about is getting the stove as hot as humanly possible.

Hi ed does it look like the one in the bottom right corner of this add or is more like the older Pot belly style

http://cgi.ebay.com/1948-KALAMAZOO-FUEL ... dZViewItem

It looks like a potbelly stove and stands about 5' high. The outer jacket is missing so it could be like the bottom right one in the ad. The grate has holes about 2" wide by 6" long. As far as the sap burning, as long as a fresh suppky is added it won't burn, once it gets boiled down to about 90% done I let the fire die down and drain it off and finish it up inside. The last little bit is critical, an extra couple minutes and it all turns to honey, then the only fix is to add water and try to reboil it but the taste is pretty much ruined at that point. I've never boiled with coal before, but I have a good tall stack on the coal beast so it shouldn't affect the flavor one bit. I'm not an expert at sugarin' by any means, but it's fun trying. The good news is the local maple fest is a few weeks after I get a chance at making my own, so if I screw up I just buy a gallon or 2.

Those slots in the grate are huge, I guess you may have to use stove... most pieces of coal in stove are about fist sized.. Or you could make a second grate to fit over the existing one to shrink the opening size. You could use rebar to make a simple, cheap grid to set over the grate.. It would reduce the effectiveness of the shaker grate, but would allow the use of nut coal.

You may just want to go buy a few bags of stove and nut coal and try them out.

Greg L

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