What type of grates and what size smoke stack for AUF arch?

[Buckfever]

I'm considering building a 2x4 arch with a blower under the fire. I'm not sure what type of grates would be needed to withstand the higher heat. Also what diameter smoke stack would be best for this size unit? I saw a 2x4 Leader Supreme the other day that had a 10" stack and wondered if that large of a stack was really needed.
I'm also debating with myself whether I should pay the extra $ and go with something like a hybrid flue pan or if a continuous flow pan would be sufficient. I'll run about 50 taps. Approximately what would the evaporation rate between the 2 types be?

[mudr]

My 2x6 came with 8 inch. I think 8 is pretty common for the 2 ft arches.

Assumptions: 1 gallon of sap produced per tap per decent day; 1 gallon per hour per sq ft of heating surface

2x4 flat pan= 8gph. 50 taps=50 gallons. 50/8= 6.25hr of just boiling
2x4 flue = ~20gph. 50 taps= 50 gallons. 50/20= 2.5 hr of just boiling.

Things to think about: Can you boil every day? If you work during the week and hold a couple days worth of sap it will add up. You may not get hit with multiple 1 gal/tap days in a row, but you can easily get up to 75 gallons over a couple days. 75 gallons is almost 10 hrs of just boiling. Also, is there any potential for added taps in the future? Finally, if you add AUF you can increase the boil rates a bit. I would assume you can hit 11-12 gph on the flat, maybe 25 on the flue if the stars, sun, and moon are aligned just right.

I ran about 50 taps last year on a rig that boiled about 7 gph. My wife is a huge help (and even spent a day boiling outside in the snow), but we both have full time jobs and two young kids. That took a lot of time. I jumped up to a 2x6 this offseason, which is probably a bit oversized for my goal of 80 taps next year but I wont be swamped and have room for expansion when the kids get older.

[acafro]

I used 1.5" angle iron for my grates and AUF under the grates.

I was getting an average of 12 GPH with 2x4 continous flow flat pan id get up to 17GPH on a good day. I'll put a picture up of my grates

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[acafro]

http://uploads.tapatalk-cdn.com/20161026/bfd71bcbbac9023533fc295f0da35870.jpg

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[MISugarDaddy]

Leader used to put 8" stacks on their 2' x 6' and smaller units, but changed to 10" about 4 or 5 years ago. Our original evaporator was a 2' x 4' unit with a flat pan and it came with an 8" stack. When we switched over to a 2' x 6' Leader with AUF, we stayed with the 8" stack and it has worked fine. I called Leader and talked with them about it and they said 8" would work okay as long as we waited a few seconds to open the door when firing (after turning the blower down) to avoid getting flames coming out of the door. Last season we had no problems at all with it.
Gary

[Waynehere]

I have a 9" on my 2x6. I learned that height makes a big difference as well. You can't have too much height. I use 2"x1/4" angle grates. As long as you have AUF, they keep cool and no warping. I keep the V up so it can fill in with ash and insulate the top of the grates.

[WESTVIRGINIAMAPLER]

We have 9" on our 2x6 evaporators and yes stack height makes a big difference. 2' of stack for every foot of length is key. If you have to 2.5 to 3 feet or more per foot of length, it pulls the heat away from the front part of the evaporator a lot of times because it pulls way too much draft and is sucking most of the heat to the rear half of the syrup and the flue pan and the front of the syrup pan won't boil much. Not always the case but happens a lot of the time when customers have to go with an extremely long stack to get above a steep roof or coupla.

[acafro]

I have a 9" on my 2x6. I learned that height makes a big difference as well. You can't have too much height. I use 2"x1/4" angle grates. As long as you have AUF, they keep cool and no warping. I keep the V up so it can fill in with ash and insulate the top of the grates.
I did the same thing with the grates, worked well last season. I cut some 2" angle iron about 2" long then welded those in place at the ends with the v up and sat the 1.5" angle iron gates in them so they are removable.



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[Zucker Lager]

Hey Buckfever:
Here's one more grate idea. 1 inch re bar. The sides of the arch have heavy rails with 1 1/4 inch holes in and the grate irons sit in loose. Concrete places in our area pre cut to length for free and re bar is cheap. Jay

1470714708

[Waynehere]

Hey Buckfever:
Here's one more grate idea. 1 inch re bar. The sides of the arch have heavy rails with 1 1/4 inch holes in and the grate irons sit in loose. Concrete places in our area pre cut to length for free and re bar is cheap. Jay

1470714708

Those look cool. I think the trick to any steel grates is keeping them cool with some AUF though. It is the extreme heat that eventually warps/melts steel down and the blower will help curb that. I have heard of people not changing their steel grates out for more then 7 years as long as they are using a blower under them...