A little help on home made evaporator

[Evella]

So this is my second year making syrup. Last year we boiled on pretty much every pan in the house we got pretty efficient at it. By the end of the year we were able to boil 55 gallons in 7 hours. So as with anything I do I was trying to rev it up. I bought a 2x4 pan and built a fire brick base with flue. We had 72 gallons and it took 16 hours to boil. The sap would bubble a lot but not reall get to the rolling boil. Not really sure what do. Any suggestions would be great.

[maple flats]

Is the pan setting directly on the fire or is it setting on the stove top or is there a slight space? Somehoe the picture 3 of 3 looks like there is a space under the pan. It might just be an illusion.
It might help if you put some firebrick against the sides of the pan. Also, how deep is the sap? It looks like maybe the pan is 6" tall and the sap maybe 4" deep. If that i correct, you want to have less in the pan at any given time. 1" might be best but be sure you maintain that depth at all times. Maybe 1.25 or 1.5 might be safer but it will not boil as fast.
Back when I had a 2x3 on a half pint arch (the fire was in direct contact with the pan) I got 6.5 GPH when I had good wood, split wrist sized, filled the fire every 7 minutes and kept the pan at 1" deep. If I had to take a break I added another inch depth, that not only gave me a few minutes but slowed the evaporation rate significantly. (I do not recall exactly how much but it was at least cut by 50% if I recall.)

[Evella]

Hey maple flats,
Thanks for the input. There is slight space in between for the metal grates. We did run it about 5 inches deep maybe that was the big problem. It was very frustrating not getting to that rolling boil when I could easily do it with an open fire. Do you think making the whole setup taller would help. It’s only about 12 inches off the ground. I made it low with the intention of not going through so much wood.

Thanks again

Here’s a pic of lat years

[plabarr]

I started out with pretty much the same setup with a 3x4 flat pan on bricks and was able to get between 20 and 30 gallons an hour depending on the wood we were burning. I think it would help if there was a little more height to it to allow for a good fire. make sure the fire is all the way to both sides too, not just in the middle. If its just that short fire in the middle you will have a hot section in the middle of your pan as the heat heads to the stack but the sides will be "cold" spots. I'm not sure if the make up of the pan allows it but I would try rotating the pan so its 2' wide and 4' long. This would make your fire more efficient and allow you to have a narrower fire. You would gain a lot more boil from your BTUs too as the heat travels down the 4' of your pan instead of just 2'. I ran mine at 1" deep but that's real tricky without a float. Its always better to go a little deeper so you don't risk burning your pan.

[Super Sapper]

Make sure all of your combustion air comes in from below the fire and none around the bottom of the pan. If you do not already you will a grate for the wood to site on so the air can come in from below.

[maple flats]

If the space is just grates that should be good. I agree, if you can turn the pan it will help some, make it a little taller will also help and give the air a way to get in under the fire (grates) will help and finally, 5" depth will never give you a good boil. Get it to at max 1.5-2" and it will boil faster, 1" will be even faster. Just get comfortable with the operation of what you have before going to 1" depth. Start it at 2", work down to 1.5" get used to that, then go to 1.25 and again get used to it and finally try to maintain it at 1". Make sure the pan is level, if not level both ways correct it and if you cant have those measurements what you want a the shallowest spot. Level is by far best.
Most arches in that size have 16-20" between the grates and the pan (my 3x8 has 18") and there is a gasket to keep air from getting in just under the pan, which then cools the pan.

[Evella]

You guys are all awesome. So changing the direction of the pan would be difficult for this year because I designed it to go that way (probably should have talked to you all first). So I raised the blocks about 6 inches and put grates in about 3 inches from the bottom. The brick is dead level since the get go and is dug in the ground by two bricks. I am a general contractor and confident that part I wouldn’t screw up. I will also run the pan about 2 inches this time which makes sense. So I guess my last question is air flow. My buddy is a welder and helped me make the doors. We installed simple slide damper in them which you can see if you look back to the first picture. I now raised the doors and was going to try and put blocking under them. Am I better off trying to control the air flow from underneath the doors? Thanks again one of the best parts of making syrup is letting my 4 and 6 year old try it at the end of the day and that just didn’t happen this last time. They spent all day helping me and were disappointed. Not a whole lot of people in Rhode Island making maple syrup so nice to be able to ask questions

[Sugarmaker]

Your doing good! And have good helpers! Yes the stack at the short end of the arch would probably get better draft?
Regards,
Chris

[plabarr]

Controlling the air from under is probably your best bet so you get the air coming in those bottom 3" under the flame and it drafts up. Not having enough air flow can slow up your boil too so be careful how tight you close it up down low. You usually need a good fire going to get a rolling boil.

[Evella]

Hey everybody I just wanted to give you an update. We got a boil going around 9 am on Saturday. By 3 pm my 64 gallons was down to about 2.5 and we pulled it off to finish. We ended up with just over a gallon of syrup. Thanks for all your help. Next time I’m going to ask on maple trader before I build anything lol

[Sugarmaker]

Evella,
Nice job! Thanks for the update!
Regards,
Chris