Wood stove evaporator

[John c]

I have this old wood stove that I am thinking about converting to an evaporator. The wood stove measures 24" x 36" and is 21" high. I am gonna cut a 20" x 32" hole out of the top so the pan will act as the lid and flames will kiss the pan. I am going to box off and brick the bottom rear portion of the firebox so the flames are forced to lick the pan, so the firebox will now be 24" x 16". I will also use a blower to force air under the fire.
I drew up this simple picture so you all can get the idea. If anyone has input, please don't hesitate!
Any idea what my boil off rate might be?

http://i816.photobucket.com/albums/zz81/Bigjohn010672/ac6ec545.jpg

[xyz5150]

How many taps are you doing ? When i built my arch a friend of mine gave me a old wood stove that i was going to customize into a 2x4 arch the only thing left is the door. The top would have to had angle iron put in to support the pan and tons of other things just to much torching and grinding.I took a set of plans from here built it out of 2" 3/16 angle iron and used the door off the wood stove it was much easier and i got exactly what i wanted but now it needs to be bigger.

[John c]

How many taps are you doing ? When i built my arch a friend of mine gave me a old wood stove that i was going to customize into a 2x4 arch the only thing left is the door. The top would have to had angle iron put in to support the pan and tons of other things just to much torching and grinding.I took a set of plans from here built it out of 2" 3/16 angle iron and used the door off the wood stove it was much easier and i got exactly what i wanted but now it needs to be bigger.

Around 40, maybe 50 taps. The pan will measure 24" X 36" with a 20" X 32" exposure to the flame.

[xyz5150]

In 2010 i started with 10 taps ended up with 20 on a 2x4 flat pan. last season i was going to do 40 on a 2x4 flat pan ended up with 93 on a 2x4 wse set. I know now that saying 40 maybe 50 is nothing but big trouble. 50 taps on 2x3 is a lot if you other things that need to done. I am no expert but i would go bigger or at least get fire under the whole 2x3. Your pan is only going to boil where its exposed to the flame.

[John c]

In 2010 i started with 10 taps ended up with 20 on a 2x4 flat pan. last season i was going to do 40 on a 2x4 flat pan ended up with 93 on a 2x4 wse set. I know now that saying 40 maybe 50 is nothing but big trouble. 50 taps on 2x3 is a lot if you other things that need to done. I am no expert but i would go bigger or at least get fire under the whole 2x3. Your pan is only going to boil where its exposed to the flame.

Honestly, when I say 40 maybe 50 taps I mean exactly that! I'm one of those guys who sets boundrys, limits and goals and I stick to them, so 40 maybe 50 taps NEXT year! "notice I stressed next year!" I'm sure it will all change again the following year, but all I will need to do is weld on a ramp to this wood stove and make a longer pan!
As far as you saying it will only boil where it's exposed to the flame. I thought that was the whole reason for shortening my firebox, so the flames are forced to touch the pan as it's drawn out the stack! No?

[xyz5150]

Thinking into the future i would make the fire box at least 2x2, a 2'x16" wont leave much room to make btu's. If your setting your pans on a solid frame like angle iron you only need about a inch of overhang on your pans so a 22"x34" hole would be fine. Doesn't seam like much but it is about 3/4's of a sqft on a 6 sqft rig thats a lot.

[John c]

Thinking into the future i would make the fire box at least 2x2, a 2'x16" wont leave much room to make btu's. If your setting your pans on a solid frame like angle iron you only need about a inch of overhang on your pans so a 22"x34" hole would be fine. Doesn't seam like much but it is about 3/4's of a sqft on a 6 sqft rig thats a lot.

Ok, I agree with the 2 X 2 firebox!

[John c]

No other thoughts? I want to get goin on this thing, but I'm really looking for some more feedback!

[C.Wilcox]

My evaporator is set up just like your drawing and I've wanted to change it ever since I first fired it up. Having the backwall vertical like that does force the flames up against the bottom of the pan, but it seems to me like mine just does not boil as well as it should. When I'm at full boil I can look in the pan and easily see where the back wall of the firebox is. That's where the rolling boil stops and the lazy boil starts. My recommendation would be to angle the back wall so that more of the bottom of the pan is exposed directly to the fire. If you keep the space between the top of the ramp and the bottom of the pan narrow right in front of the stack the fire/heat will still be drawn up against the bottom of the pan before exiting up the stack. Just my thoughts anyway.

[seclark]

John, how much syrup are you looking to get?Will you be boiling in a building or outside.I boil in a 10 x 8 sap house on a 37"x37" flat pan on a barrel setup and I get around 10 gph with a preheater and hood.I made 4 gallons of syrup an figuring at 40 to 1 per gallon,and thats with a good estimate, I still boiled a long time to get that and I only had 20 taps.I am now making my pan 24 x 37 and will put in dividers so I can hopefully draw off syrup sooner instead of batch boiling.Your stove idea is fine but I think your boil time will be quite long and with that many taps you could be overwhelmed with sap.Just my thoughts.

[Revi]

I think it's a great idea. You will have something like an evaporator for way less. What are you going to use to block off the lower corner? Mild steel? If covered with firebrick it will be fine. Go for it!

[John c]

I think it's a great idea. You will have something like an evaporator for way less. What are you going to use to block off the lower corner? Mild steel? If covered with firebrick it will be fine. Go for it!

I will be boxing it off with 1/16" steel and then use firebricks. Also don't forget I will be introducing air under the fire which should make a huge improvement and I will also have a damper in hopes of restricting the flames from exiting too fast!

[Revi]

It's a great idea. Will the blower blow the flames out the door when it's open?

[John c]

It's a great idea. Will the blower blow the flames out the door when it's open?

No because eventhough the blower will be in the rear, the outlet will be pointing slightly back away from the door with exactly that concern in mind!

[C.Wilcox]

Also don't forget I will be introducing air under the fire which should make a huge improvement and I will also have a damper in hopes of restricting the flames from exiting too fast!

John,

Your boiling rate will improve slightly with the blower, but not substantially. Don't mean to be a downer, just wanted to give you some real feedback from a person that has nearly the same setup. In regards to the damper, don't bother. You won't want it. The fire is going to want lots and lots of air and a damper will only smother it. I had one in my stack for about a day and then took it out. Make sure you have enough stack. I used about 8-10 feet of stovepipe last year and when I extended it another 6 feet this year I noticed a big improvement.

[Peepers]

John c - how did this project turn out? I'm thinking of modding a wood stove into an arch this year as well so if you have any pics or nuggets of wisdom from your build I'd love to hear em!
thanks

[Sako]

Peepers, do a search for user Name MrGriz. My neighbor posted photos of the stove I built. Started out with a used wood burner. See the photos, and I will recommend doing AOF. I used 2x3 rect tube for the air chamber and my pan base.
Chris

[Peepers]

good deal, found it: thread (http://mapletrader.com/community/showthread.php?13099-2-Saps-the-new-the-good-the-bad-and-the-ugly...&p=153421#post153421)

Looks like the wood burner had a burned out back so you guys cut it apart and made it into an awesome arch, I love it! the pics are a little small but it looks like there are some small tubes welded onto the 2x3 rect tubing for the AOF? And following the PVC piping from your blower it looks like you have air underneath as well - do you have to turn the fan off while stoking it or does it have enough draft suction to behave and not shoot fire out the door at you?

[Sako]

The blower you see in the pictures was first attempt with a Jennair cook stove blower, it helped the boil(yes it was under and over) after the test boil I found a blower from belt driven lawn mower collection cart. (5 blade) that thing makes the boil become violent.
We do shut the blower off, when we open the door I am not sure if we are over doing it but the fire brick are glowing and we are seeing stack temps around 1800.