Making Maple Syrup with my rocket stoves

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Making Maple Syrup with my rocket stoves

Postby hpmer » Mon Apr 13, 2015 11:55 pm

I just finished making maple syrup for the season and thought I'd recap the process for anyone interested in how it works.

Maple syrup is made by boiling down the sap from one of a half dozen different species of maple trees, with sugar maple being the preferred. Depending on the sugar content of the sap, it can take anywhere from 30 to 40 gallons of sap to make one gallon of syrup. Given the amount of fuel required to boil the liquid down for that long, I find the rocket stove to be the ideal stove for small batch production.

I start off by freezing the sap as I collect it since sap, like milk, will spoil if not kept cool. Then the challenge is how to thaw it out and heat it up to add to the already boiling sap. So this year I built a second stove and documented the process here http://www.permsteading.com/viewtopic.php?f=6&t=647.

So I start the boiling process by heating up a pan of water on my new stove and setting a frozen gallon jug of sap in it to thaw out.
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Once I have several gallons thawed out, I heat them up to the steaming point before adding it to the main pot:
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I add the new sap to the existing pan via a smaller feeder can, since the boiling point of syrup is higher than that of sap (which is mostly water). Syrup is syrup when it boils at a temperature of 7 degrees F above the temperature that water boils at that location on that day. So the new sap is by definition at a slightly lower temp than what's in the pot and one does not want to "kill the boil." If you look closely you can see an egg in the pan that I use for a visual clue as to how much has boiled off. I try to keep the egg covered and add more hot sap when it begins to show itself. Plus when you're done you have a maple syrup flavored hard boiled egg.
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Periodically, bubbles will form on the surface of the pan which insulates the top somewhat and doesn't allow the steam out. So that gets skimmed off:
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Here's a shot of the main stove and pot supports which hold the pan slightly above the riser. I made them with the same mix that the stove body is made from. There is a small groove into which a piece or rebar can rest to support the pot while giving enough clearance for the exhaust gasses to ensure a clean burn:
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The batch boils down to almost syrup and then gets finished inside on the stove where I have more control over the stove temps.

So, that's how I do it. If nothing else a great way to spend an early spring day when there is still snow on the ground and get something great in the process.
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Re: Making Maple Syrup with my rocket stoves

Postby hpmer » Tue Apr 14, 2015 12:40 am

And a video of the thing in action. Truly amazing the fire power of a few small sticks:
http://vid1028.photobucket.com/albums/y344/hpmer/Mobile%20Uploads/VIDEO0067_zpsbeof8rdg.mp4
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Re: Making Maple Syrup with my rocket stoves

Postby mannytheseacow » Tue Apr 14, 2015 1:05 pm

Good stuff, Hpmer! I've been jonesing for some updates on what people are working on. I really like that egg trick. That's a good idea and I certainly have plenty of eggs to use.

Have you ever thought of making an insulated pot skirt? If you had some definite pots that you use year to year I could see a real benefit to using one of those Donkey/Africa masses with a couple holes for cooking and keeping the heat around the pots.

I'm curious about your collection methods, too. I had posted my syrup collecting somewhere on here but I can't find it now. Essentially, I just stick 3/8" barb fittings in a tree and tie an old milk jug under it. I have a client with a maple grove with hoses connecting all the trees. It isn't used any more and he has offered me to make use of it. I've let that opportunity pass me by for 3 years now but it's about 45 minutes away so the reality of going there all the time just doesn't make a lot of sense when I have my own trees to tap.

I worked up in northern Minnesota one winter and we had a big syrup factory on site there. I didn't have much to do with it, myself, but just watched. They had a complete sugar shack with tens of acres hard-lined into the shack, which had a wood-fired boiler in it. They raised most of the money for the research center through conservation education programs and selling maple syrup.

So how much did you end up with this year?
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Re: Making Maple Syrup with my rocket stoves

Postby matt walker » Tue Apr 14, 2015 2:27 pm

Yeah, loved reading about that Hpmer. I sure wish I could get some sap flowing here, that looks like a process I would really enjoy. I too am curious about how much, and from how many taps?
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Re: Making Maple Syrup with my rocket stoves

Postby hpmer » Tue Apr 14, 2015 4:52 pm

A wind screen/pot skirt is a good idea. I rigged up a make shift one and the difference was unbelievable. But I didn't have the sexy fire photo with the screen so posted the other. Another one for the big pot would certainly help as well.

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I ended up with less than a gallon of syrup. The rule of thumb is you get 1 quart of syrup from each tap (or about 30-40 quarts of sap). I had four trees, one of which didn't produce anything. Had the same problem last year and the hole never healed, so I'll have to pay more attention to what's going on next year.

As for collection, I just use a 1 gallon milk jug with a regular maple tap. It maxes out on the really heavy flow days but the trees are still relatively small and it has been sufficient so far. As the trees get bigger I may change to a 5 gallon bucket to make it easier. I saw some food grade ones at Lowe's the other day for $5 or so.

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