Expanded cinder block evaporator

[Tithis]

I'm a pretty small maple hobbyist and this will only be my third year. I'm planning to do 21 taps this year over 30 trees totaling 39 potential taps, plan is to tap and test most of them and only use the sap from the best of them.

I've been using a cinder block and steam pan evaporator for the last 2 years with some minor improvements the second year. This year I'd like to add a second pan to the setup to decrease boiling time and/or increase efficiency.

Last year raised the whole evaportor off the ground slightly and put a firegrate inside to allow better airflow, I doubled the height of the stack and then just leaned some duct metal against the opening as a simple door. I don't think it did a ton for my peak evaporation rate, but it certainly made achieving that peak easier. My question I guess is if I should simply just extend my evaporator and make it longer, possibly giving enough room for an actual arch in the rear, or should I make the arch wider to give me a larger firebox? Should I do something different all together?

I guess final question would be what kind of improvements do you think I could get in boiling time by extending the evaporator and adding an arch? Last year I knew quite a bit of heat was being wasted and the air coming out of the stack was still hot enough to make leaves catch fire.

Pic of last years before adding enough section of stack.
http://i13.photobucket.com/albums/a270/Tithis/Maple%202012/100_9013.jpg?t=1328214520

[happy thoughts]

I don't know how much you want to expand but the block arch I used for the first time last year was barely bigger than yours and just a wee bit wider and one block course taller (less bending) The major difference with yours was the number of blocks across the back end. It easily fit two pans turned crosswise- a 90 degree turn from your positioning. A sand ramp to the back, fast plugging the stack into the block, an old grill grate and a crude door like yours and we were cooking with good air flow. But 21 taps you say? I dunno, I think you're going to need more than 2 pans or you're going to die from either hypothermia, smoke inhalation, or just plain old sleep deprivation:) A 30 gallon boil off with 2 pans still took us 6-8 hours or longer.

Do a search of this forum for block arches to see what is possible. There are some incredibly long set ups that you could convert into a pool for the summer:cool:

[valleyman]

Hi,
Yeah Happy Thoughts has a good point about how long you'll be out there. I have a 4pan set up crosswise, 4 courses high on the block. My set up rips and it still takes 3-4 hours to get 25 gallons down to 1 1/2 and around 6 hours to boil down 40 gallons to 2 1/2 gal. I finish on propane "turkey fryer"

If you feel like it, look up Valleyman on this site or feel free to visit http://www.gregkarasmaple.blogspot.com

[Tithis]

My one pan fared decently the last two years, I figure two would be enough unless its a really good season sap volume wise.

Any thoughts on the arangments of the pans? Distance between arch and bottom of the pan?

edit: Maybe I'll think about getting a third. I just bought the second pan today at a restaurant supply store used for $15. I gotta go back tomorrow to return a sheet pan I bought (got a 3/4 sheet pan instead of 1/2, it barely fits in my oeven)

[Bernie/MA]

I made a pan/arch setup a little bigger than yours, 18"x36" pan with 2 lenghtways dividers for my grandson. We used cement blocks for the arch like yours but I made a frame out of angle to sit on the blocks. It has a hanging door and a grate with an 8" stack on the back end. He made 5 gallons of good syrup in 3 weeks in 2010, after school and weekends. I'm a retired welder with a small shop and I'd like to make more of them.

[Maplehobbyist]

The setup I used last year was two pans set in a metal frame that I tapped and screwed together sitting on blocks. (I started a thread with questions about it so there are some pictures on the trader somewhere.) The pans are exactly the same as yours. The front pan was perpendicular to the rear one, which was arranged as yours is. I got somewhere between 3-4 gph. I had 15 taps and it made for some really long boils, especially during those few days when the sap was really running (2+ gals of sap per tap for some taps). The fire box was only under the front pan and the rear area was filled in so the pan was about 2" above where the heat was sprinting to the stack. And I do mean sprinting. When I was doing some test boils, I could see the soot pattern under the rear pan was v-shaped; as the heat left the fire box it went straight to the center of the stack. I put a fire brick under the rear pan to try to force it out to the sides and it seemed to help.

I'm already going to change to three pans for this year because I want to do more taps, not more time. The front two will be arranged parallel to each other and perpendicular to the rear pan. I'm really trapped for space in my sugar shack which is 8'x9' (not that I'm complaining when I see yours is set up out in the open) so I can't go longer. I thought about running them all in the same direction (opposite of yours) to make it a bit shorter, but didn't think that I'd be able to get any kind of a boil on the rear pan if I did that. I'll be able to have a larger fire box, which means more heat and I won't have to cut the wood so small. One thing I'm questioning is whether a 6" stack will be large enough to draw out that heat. I just put in the 6" last year and if I have to replace it...when will it ever end?

[SeanD]

The steam pan block arch is super simple and you get a ton of bang for your buck. Turn your pans 90 degrees and try to get to four or even five pans. You'll maximize all that heat before it goes up the stack because the pans set right into the fire. If you turn them, you won't need to add much more stack if any. Four pans side by side (not end to end) is only about four feet, so you'll only need eight feet of stack. Each pan will get you between 1.5 to 2 gph.

Figure out how often you can boil and go from there. Thirty-nine taps will average thirty-nine gallons a day (sometimes more, sometimes less). Four pans will knock that out in about five hours if you boil every day. If you go with something closer to 30 taps, you could be done in four hours daily.

If you go with a fifth pan, you can knock another hour off of your boil times for the same amount of wood and effort. Riley Sugarbush used to have a video on here somewhere of his four or five pans set up this way. He had a $25 leafblower from Walmart stuck in there and the thing raged.

The slope is good advice and so is having a grate. That's the key - get air in there. When I put my grate in I had to go to a third course high of blocks to leave enough room for the wood and flame because the pans set down into the space.

The beauty of this set up is if you cut back on taps you can cut back on pans, or if you expand you can just add more pans to what you have.

Good luck,
Sean

[Tithis]

I think I've settled to go with 3 pans. Out of the 39 potential taps I'm only going to actually tap 21 of them, my plan is to spend the first few days tapping groups of them, gauge their sap flow and test their sugar, then for the rest of the season I'll only collect from the 21 best. Figured thats the best way to get the most of out my taps.

Taking that somewhat extreme route because I've never even gotten half the syrup you'd expect for the number of taps I've done ( #taps x 10 gal / 40). First year I blame how crowded the trees were, second year I'm just kind of writing off as being a poor season for basically everyone.

In the past I've done 2 boils a week on average. Now presuming I actually get an average of 10 gallons per tap during the season, say over a 4 week season thats only 26.5 gallons to boil off. with 1.5-2 gph rates per pan I figure 3 would let me go through that in 4-6 hours, which seems reasonable to me.

[Maplehobbyist]

I would like to add that if you are putting non-heated sap into one of the pans, the boil rate on that pan is much reduced (depending on how you do it), so calculate the overall rate based only on the other pans. Anything you get from the pan you put the raw sap in is a bonus. However, as someone else pointed out (I think it was Sean) the space taken by an additional pan helps the boil rate more than the space taken by a pre-heater.

[Swingpure]

I would like to add that if you are putting non-heated sap into one of the pans, the boil rate on that pan is much reduced (depending on how you do it), so calculate the overall rate based only on the other pans. Anything you get from the pan you put the raw sap in is a bonus. However, as someone else pointed out (I think it was Sean) the space taken by an additional pan helps the boil rate more than the space taken by a pre-heater.

I had read this post before, but in rereading it, if I make my evaporator 3” longer, I could add a fifth steam pan, and remove the 10.5” warming plate. The fifth pan would be a better sap warmer, freeing up the fourth pan to be a true boil pan and adding to the overall efficiency of the evaporator. I am going to check out tomorrow how easy that will be.

[Swingpure]

I checked it out and I can easily add three inches to the length of the evaporator to add a fifth pan for sap warming. The only issue is that the pan would partially block the stove pipe entrance. Right now, there is 10.5 inches after the fourth pan for the heat to climb up and go out the full diameter of the stove pipe. If I add the fifth pan, only about 2” of the stove pipe would be fully exposed and only about an inch from the edge of the pan for the heat to go out the full diameter of the pipe.

If I do this, would it totally screw up my draft?
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[DRoseum]

Can you shift the exhaust port back?

If not, you could raise that last pan a few inches or use a shallower depth pan (keeping the bottom up higher than the others). Could probably achieve that with a firebrick on each side to hold it up.

[Swingpure]

Can you shift the exhaust port back?

If not, you could raise that last pan a few inches or use a shallower depth pan (keeping the bottom up higher than the others). Could probably achieve that with a firebrick on each side to hold it up.

Thanks, I had though about the shallower pan, but when I looked at my setup, I though the bottom would just sit in the same place, I did not think about raising the ledge it sits on. I currently have six inch deep pans. I will go with a 4” deep one, and raise the ledge two inches.

I set it up on a concrete pad I poured and I am just about at the limits of the pad, so the raised pan is the way I will go.

Thanks again, I will work on it tomorrow. I ordered the pan tonight.

[Swingpure]

I added the three extra inches in length to the evaporator today. That will allow me to add a fifth pan. Raising up the level 2” for the fifth shallower pan, really opened up the opening for the stove pipe. The new pan is on order and when it arrives, hopefully everything fits perfectly level wise.

Thank goodness for a diamond stone cutting blade on the circular saw. I had a lot of cutting of new patio stones to do, to add the 3 inches.

If the fourth pan boils nicely for me and the fifth pan really warms up the sap, this move might make for a 25% improvement in efficiency. I will also be preheating two pots of sap on a dual induction stove near the evaporator. That should also help.

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[DRoseum]

I added the three extra inches in length to the evaporator today. That will allow me to add a fifth pan. Raising up the level 2” for the fifth shallower pan, really opened up the opening for the stove pipe.

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Looks great