Evaporator GPH

[Toblerone]

Hi All,

I have a small operation (25 taps) and am currently using 5 "steam-table" restaurant pans over a concrete-block arch with a turkey-fryer preheater. I would say the size is about 2x5 or so total surface area.

I am boiling between 12 and 15 gallons of sap per hour one that setup. Since I work a 40-hr/wk job, I usually wait until I get between 80 and 120 gallons of sap before starting a boil, which gives me about a 7 to 10-hour boiling day.

Is 12-15 GPH about what I should be getting on a homeade arch like that?

I am hoping to expand the operation to 30 taps next year, and then up to 50 the follwing year.

What kind of rate could I expect from a Leader Halfpint? Or from a 2x6 drop-flue arch, or a 2x8? How often (on average, per week) would I have to boil on those arches to keep up with 50 taps while keeping a 10-hour maximum boiling day? Are there any ballpark guesses? Or are there just too many variables?

I am trying to decide what route to take the next couple of years. Any help would be greatly appreciated.

Thanks in advance,
Dave

[Fred Henderson]

A 2x4 Leader drop flue is rated for 50-100 taps and a 2x6 for up to 500 taps. But that is for a 9 hour day.

[Michigander]

Some rouugh guidelines that I have been given are:
A flat pan (no flues in the sap pan), you can figure a boil of about 1 gal/hr per square foot of boiling surface.

If you have 4 inch flues in the sap pan, you should be able to get 2 gal/hr per square foot of surface (2x6 = 24 gal/ hr). If you have 7 inch deep flues, maybe 3 gal/hr per sq. ft.

These are rough numbers but when you compare them to manufacture's provided evaporation rates, it comes out quite close.

Other factors can certainly affect it like forced draft, preheating sap, reverse osmosis, etc. I might be all wet but I think these guidelines are close for a starting point. Then you still must decide how may hours you want to man that evaporator each day and don't forget to add an hour or so at each end for start up and cleanup.

[Fred Henderson]

I have a 2x6'6" flat pan and I can do 35 gals an hour. At the last calulations about a week ago that is what it was.

[Michigander]

Fred, that is really doing good! My flat pan is 2x5 or so and I have a homemade forced air on it. On a good day I can get maybe 18 to 20 gal. per hour. Before I put the forced air draft on it I was running about 12 to 13 gph on most boils. My sap is not preheated and I think my wood should be drier also. I suppose that would help a lot.

There sure are a lot of variables that come into play.

[Toblerone]

Wow. 35GPH! I am amazed. Is that wood fired?

If the Leader Halfpint is good for 50-100 taps, does that mean boiling every day for 9 hrs? Or every day that sap is running?

Right now I have to limit my boiling to 1 to 2 days per week or I think my wife will kill me this year. We both have 40/hr week day jobs, a 4-year-old and a 10-week-old. Since I work from home, I take care of the 10-week-old at home while I work. So basically I hardly see my wife as it is.

Also, do all of you split your own wood by hand? Any secrets?

Thank you for all your replies,
Dave

[Fred Henderson]

Yes, 35gph is real good . With the parallel the sap enters the pan at 180 drg and I try to keep my stack temp between 600-650 drg. I also built my own insulated arch and I have a heat dam in the back near the stack. If I want to get faster I would have to go to a 2x8 w/ a hood. Most 2x6 flue types are only rated to do 30 gph. It is wood fired, but like I said I built everything. Guess I kind of new what had to be done to get that rate on a flat pan.

With wood fireing it takes me about a good 45minute to an hour to really get things cranking. Heck the fire is out when I leave the sugarhouse and the thing is still boiling from all the heat in the bricks. So when I decide to shut down I want to have a min of 50 gals left in my storage tank.

[Michigander]

Toblerone, I am lucky to have a hydraulic wood spliter since I also heat the house with wood. During the winter I cut the fire wood and split it all into sizes that fit best in the house stove. Then, when sugaring season starts I use the spliter to split it down further into about 2 and 3 inch sizes for the evaporator. Last year I did not get the wood out of the woods until late so it was not as dry as it should be. I would like to get to the point of sugaring with 2 year old wood and keep it all covered in a wood shed by the evaporator. Many on this site have said that properly dried wood is the secret.

[WESTVIRGINIAMAPLER]

A 2x6 will do 25gph stock and a 2x8 around 35 gph stock. After you learn how to fire them, you can do a little better and modifications will help. A 1/2 pint will only do around 5 to 6 gph stock, so if you can get an evaporator, you will be a lot happier.

As far as your current setup, if you can just put the fire under the front 1.5 to 2 feet of the arch and then build up the rest of arch up next to the pans and insulate the walls good, then you may be able to do a little better than that. I used to boil on a 3x6 flat pan and I could do around 30 gph and I have an old 5x7 King flat pan and I could get 50 gph once it got hot. :D

[Toblerone]

Fred or Brandon, how close to the bottom of the pans should I "build up the rest of arch up next to the pans and insulate the walls good?"

I tried to do that this year to about 6" and I had trouble keeping the back pans boiling.

Also, I am contemplating making a new flat pan evaporator. Assuming the thing is insulated well, how thick do my sides need to be? Also, what do you think about the idea of starting with a common wood stove and just extending the back end of it to accomodate more pan?

Also, where is the best place to get firebrick? Around here they are over $2 a piece. Seems it would cost a fortune just for the bricks.

BTW, I love this forum. In my neck of the woods, the closeset sugarer is over an hour away so I don't get to meet any of them to share stories and ask questions. Thank you all, and thanks to mapleguys.com.

Thanks,
Dave

[WESTVIRGINIAMAPLER]

Firebrick are a little pricey, but in the long run, they will last and provide many years of service. I would build back of the arch up to about 2.5 inches and then put a layer of 1" ceramic blanket on top of that and that will give you about 1.5" of fire space. Also, if you can put the ceramic blanket on the walls, it would help a ton too.

You can buy a roll of the 1" ceramic blanket on ebay for fairly reasonable price. When I used to boil on the 5x7 and 3x6, all I used was a cinderblock foundation that wasn't insulated at all. I had to take it down every year, so I made something that was easy to put up and take down at the end of the year. :)

[Fred Henderson]

My arch is built so if I ever wanted to add a flue pan set up I could, so mine is about 8" from the pan. Fire brick are when you find them. Usually a block plant or stove store. Fire brick do not insulated very well but they do keep the metal from burning out. The ceramic blanket is the key. At the stack end of my arch is a type of heavy steel damper that only allows a 1" space sides and bottom so the heat stays under the pan and not all up the stack.