Block evaporator - please review my plan

[Woody]

I decided to build 2x6 block cooker instead of buying a pre-fab. Hopefully it's a more economical way to go so I can free up cash for tapping supplies and woods transportation (4-wheeler).

I'm thinking 3 or 4 courses high with a couple used pans or have a couple made (2x2 syrup pan and a 2x4 raised flue back pan.) I plan on dry fitting the blocks, filling them with sand and having a step down between the back flue and front syrup pan so I can control the flow rate with a ball valve. I'm thinking the fire box will be about 24" long and lined with fire brick and refractory cement with a grate 6" off the ground for a blower space if I add it down the road. From the fire box I'll slope the sand up to about 4 inches below the bottom of the back pan. And then keep that 4" flue height the rest of the way to the rear chimney pipe transition.

I'm planning on having the edges of the pans sit on some sort of insulation bead laid on angle iron corners.

Don't know how I should do a door into the fire box or how to connect the flue/chimney transition to the back block wall. All I know, from what I've read, is the chimney should be about 12' to 15' high and the transition from the flue to the chimney should be the width of the flue in order to equalize heat on the back pan.

Last year was my first year at 135 taps and I would like to double that this year. I'm sort of committed to working by myself. I'll have a little help from my teenage girls but that's not predictable, and neither are they..... I might enlist thier volleyball team for big run days and donate some syrup sale money to the team. I figure if I build it right I should be able to boil for that many taps and still have time to collect. Good run days will have me hoppin' but for the most part I should be able to swing it.

Would really appreciate any thoughts or advice.

Thanks

[TapME]

Woody take a look at my pics and see if it helps you. Ask any questions and I may the answer, if not I'm sure there is help here to answer them. I did 210 taps with mine this year and will probably do 400 next.

[Haynes Forest Products]

Woody. My first homeade arch was on the ground using the ground as the bottom of the fire box. It worked but was a pain in the back. If your going to make it semi permenant start with 2 rows of blocks under the fire box and fill with sand and cover with a piece of sheet metal for cleaning. in a pinch A good heavy piece of metal will work as a door will let in air for draft and with a handle you can move during firing.

[Woody]

Thanks for the help you guys. Does my pan configuration make sense? The 2'x4' raised flue back pan and then a 2'x2' syrup pan up front? Also:

> Is the flue height of 4 inches below the back pan enough?

> Do you have suggestions on the transition in back from the block to the chimney?

> Is the overall 2'x6' size adequate o should I go bigger for the future? I'm thinking I might be trying to buy some sap too.

> Is a fabricated metal evaporator necessarily any more effective than one made from block? Doesn't it all depend on the pan type and arrangement?

thanks,

[Haynes Forest Products]

Once the flue gases and heat are used and no longer needed out the stack they go so just after it leaves the flue pan it should go out the stack. Like in other pictures you want it to leave the arch in a wide pattern the same size as the very end of the flue pan so you dont have cold corners. Use a transition pipe.

[vermaple]

Woody

A couple or four points and some questions. Are you buying a set of pans w/ 2x2 front and 2x4 raised flue pans, or making some pans ?

How much bigger are you thinking in the future ?

Three hundred taps could make you a very busy man with a good run, but it is very doable. A few enhancements in the future would make it a piece of cake. You could even strech a 2x6 to 500 taps without much trouble, to give you a feel for expansion.

For a naturally aspirated evaporator you should have at least 12-16 inches under the grates for draft so the ashes do not accumulate and choke off the draft.

A fire brick lining should be ok although heat might still be a issue if you ever go to a forced draft.

Build up under your flue pan should be to within an inch of the bottom of flues to force the heat up into the flues and the pan. The slope should reach that point about a foot from the front of the pan.

I suggest a 1/4" steel plate about 8" wide with a cut out and collar on it to set a stack base and use a 7 or 8 inch stack. Start with a stack height off 12' and add to it if needed.

I hope this helps.

Vermaple

[Woody]

Thanks for the advice. I was planning on buying both the raised flue back pan and front syrup pan, from where I have no idea. I'm not a welder but wished I was. Maybe some used pans will come along before next season. Although I don't seem to see much for used drop or raised flue pans. I was also thinking of looking into those drop tube pans that WF Mason makes.

[3rdgen.maple]

Woody I would keep the pans level and use a float box to regulate sap levels. You will be constantly changing the valve between the pans as boil rates change. If you walk away for a minute and she starts to boil hard you might be in trouble. Also I know you probably are anxious to get building your block ARCH you might want to get your pans first. Hate to see you get a 2x6 arch built then get a smoking deal on a set of 3x8 pans. I also would fill the first row of block where your doors are gonna go with concrete. That way you can drill them out and put in some anchors for the hinges on a door. Even if you start with just a peice of metal covering the opening that way you will be set to upgrade to swinging doors. And last peice of advice I have is build that sucker to a confortable working height, the less you bend over the easier life is gonna be.

[PerryW]

I ran 280 gravity taps on a factory built Grimm 2x6 in 1988 and it was too small. I don't know your sugarbush setup, but I'd spend the money on a bigger evaporator instead of the 4-wheeler.

From the fire box I'll slope the sand up to about 4 inches below the bottom of the back pan. And then keep that 4" flue height the rest of the way to the rear chimney pipe transition.

On my raised flue 3x10, the ramp goes up and almost touches the bottom of the flues (probably 1" clearance) and there is only 1"-2" of clearance between the bottom of the raised flues and the sand for the length of the back pan. This forces the fire right up into the flues.