Drop Flue with Muffin Pans?!

[mcgeec]

Hey everyone,

I am a long time reader here with a backyard operation in Nashua NH. I had 35 buckets and a evaporator with a 2 by 2 pan and 2 by 4 flat pan. I have been trying to figure out how to increase my evaporation rate. I have wanted to try drop flues in by upper pan but the task is beyond me. I have zippo welding skills. All my metal work was done with a hacksaw thus far.

A week ago, I had an idea. King size muffin pans are like ready made drop flues! They muffin pan has six "wells" for muffins. Each well in a king size pan is 3.25 inches deep and 3.5 in diameter. The overall pans are 14 by 9 so I could fit four into my 2 by 4 evaporator pan.

The question is how to connect the muffin pans to the evaporator pan. I plan to cut a hole in the evaporator pan large enough to just fit the muffin pan so the lip of the muffin pan rests on the bottom of the evaporator pan. But then what? How can I make the connection water tight? I found some high temp food grade sealant, which I can compress between the two pans. But will that work? If not, are there any other options??

As you would guess, I do not want to take the hacksaw to my pan until I know I can seal up the hole I cut. Any and all advice would be appreciate.

[spencer11]

thats a really good idea...now you got me thinking! you could solder it but i dont know if it would melt or not. you could also put drop tubes in your pan. rileysugarbush did this and has some pics of one. all it really is is you cut holes in your pan and get copper tubes and solder them in and put caps on the bottom. usually they are about 6" long and an inch in diameter. that tripples your boil rate in that pan to. hope this helps and makes sence.

spencer

[RileySugarbush]

What are your muffin pans made of? That will be one of the things to figure how you seal them up to the bottom of a pan. I like your creative thinking!

If you want to look at the drop tubes, many have had good success with them. I sure did. They are pretty easy to do and only involve a little soldering.

[spencer11]

how much would that increase your boil rate? if i did my math right it would be about a 2 gph increase? it dosent sem like it would be worth it if i did do my math right... about 1 gph per 1 sq. ft. right?

spencer

[Ausable]

Hey Urban - Something very important that You did not mention. Do either one of the two pans you now have - have deviders in them? 2'x6' is a good overall surface area for boiling - divided pans that are interconnected would be an easier build then adding muffin pans for a drop flue effect. Drop flues in the sap pan would be a plus but so would devided pans with the channels interconnected for a flow thru setup --- just a thought ---Mike---

[spencer11]

do dividers up your boil rate or just make it a continous boild instead of batch boiling?

spencer

[Jec]

It makes you draw off less but more frequent. It also reduces boil kill when cold sap is added.

[spencer11]

thats what i thought. i would put dividers in your pan but i dont think the muffin pan flue idea is worth the work. just my .02.

spencer

[Ausable]

Spencer and Jec --- I see You both have 2'x5' evaporators and so do I. Mine is divided and homemade with a fuel oil tank arch. Sap Pan is 2'x2' has one divider (2 channels 12"x24") and the Syrup Pan is 2'x3' has two dividers (3 channels 8"x36") and all interconnected. Add sap in the first sap channel and draw off at the last syrup channel and yes it is more efficient then the batch method as you probably know. This year I have to figure my gph boil off rate so I make more sense - lol ---Mike---

[sirsapsalot]

Would you use the muffin pans as a raised flue or a drop flue ? what would work better you guys have me thinking.

[spencer11]

ausable, my evaporator is really a 2x6 i extended the oil tank a little bit and i use steam table pans with the batch method and it sucks. i would love to have a continous flow i just could not afford it this year so i went with steam table pans. next year is when the high efficent 2x5 is going to be built...i would personnally have a raised flue pan if i were to buy one but with this type of "flue" i dont think it matters. i still wouldnt do it cause i dont think it would make the boil rate much better than you are already getting.

heres the math. 3.5" across X3.25" deep=11.375 X 6=68.25sq.in. X 4=273 sq. inches/12/12=1.895 sq ft. if i did my math right and this makes sence you would only get about another 2 gph. not worth it in my mind. just my .02(i would go with the drop tubes) hope you dont take any offence!

spencer

[Ausable]

Spencer - Thanks for the reply and no offense taken. I'm always learning and having fun in the process. Some of my Kids and Grand-kids are starting to get into making maple syrup and that makes me a happy old camper. Heck - One of my Grand-daughters and her Husband made some of the nicest maple I've ever saw - their first year and I sure didn't take any offense there either. I really like these sites and all the ideas and advice and yep - some are a bit touchy at times - but my Dad told me years ago - You can learn from almost anyone - even an idiot is bound to know something you don't - so listen. LOL - Not always easy though. --- Hey Spencer -- have a great Syrup making year. -----Mike----

[RileySugarbush]

Spencer, your math is off a little bit. The added area per muffin is the sides of the cylinder. That is height times circumference. Circumference is pi X diameter. The area of the bottom is the same as the hole.

Each muffin adds 3.14 X 3.5" X 3.25" = 35.7 sq inches or about a quarter of a square foot. So 24 muffins add about 6 square feet.

Still not a great way to add area. Especially if you are considering using sealant. I think the simplest and easiest method to add flues to a flat pan is to solder in copper drop tubes.

[spencer11]

I thought my math was off a little bit. That just shows how I have a 70 in math class right now! LOL

Spencer

[1badsapper]

ausable, my evaporator is really a 2x6 i extended the oil tank a little bit and i use steam table pans with the batch method and it sucks. i would love to have a continous flow i just could not afford it this year so i went with steam table pans. next year is when the high efficent 2x5 is going to be built...i would personnally have a raised flue pan if i were to buy one but with this type of "flue" i dont think it matters. i still wouldnt do it cause i dont think it would make the boil rate much better than you are already getting.

heres the math. 3.5" across X3.25" deep=11.375 X 6=68.25sq.in. X 4=273 sq. inches/12/12=1.895 sq ft. if i did my math right and this makes sence you would only get about another 2 gph. not worth it in my mind. just my .02(i would go with the drop tubes) hope you dont take any offence!

spencer

Is there an actual formula to determine evaporation rate?

[spencer11]

on a simple flat pan like a 2x4 one i have heard 1 sq/ft= 1 gph. so 2x4=8 gph. thats what i use anyway. i have heardit is acurate and its easy.

spencer

[mcgeec]

This is such great feedback. Thanks to all of you. I really appreciate it. I feel like I have a celebrity responding - I read and watched all of RileySugarbush's postings on this.

A couple of thoughts.

1) Someone asked if my upper pan is divided. It is, so I have two 1 x 4 channels in it that flow to a lower open 2x@ pan with a draw off.
Someone else asked if I was thinking drop or raised. I am thinking drop so the exhaust has a straight shot through and around the muffin cups.

2) I had been thinking about trying the drop tube for two years but I am worried about the number of functional soldered connections I would have to make. The muffin pans mean I have to only deal with four big holes (about 9" by 14") and the pans will fit right in. I have no experience with soldering and I have this picture of making the hole in the pan and never being able to fix it. I would much prefer the drop tubes - more surface area, faster boil, learn a new skill. I just cannot figure out how to pull it off. For example, I think I could put the caps on pretty easily. I watched a bunch of youtube videos on that. But when I connect the tube to the hole in the pan, I have trouble picture how to keep the tube and pan steady while I solder.

Also, I have done some pricing and the muffin pans seem cheaper. The pans are $10 each plus two tubes of sealant and I can be done for around $60. I think the copper tube would be more given the cost of soldering equipment and materials. I would love to be wrong about that.

3) I love the calculations. I have it at an increase of about five square feet using the calculation based on the area on the sides of the cylinder. I agree that the bottom of the muffin pan is the same area as the bottom of the flat pan. In other words, additional area = (2)*(pi)*(radius of the muffin cup)*(height of muffin cup)*(6 muffin cups per pan)*(4 pans) Given that I have 12 square feet, currently, I am pretty excited by 5 more.

4) I hold out hope that having a drop flue will be better than five more square feet more flat pan. I suspect that these muffin cups, like any drop flue are better heat exchangers than flat pans because the sap is surrounded on five sides by the sides of the muffin cup.

And finally, my plan. I will be testing this out this weekend with a sacrificial couple of pans to see if I can make a tight seal that can handle some heat. I will keep you posted. If it is terrible, I am sure I will be back dreaming about drop tubes. Thanks again for the feedback.

[spencer11]

i would love to hear how it turns out.

spencer

[Ecnerwal]

The muffin pans are made of aluminum or something like that? If you said, I've missed it.

And you're going to "seal" them in with food grade silicone, or something like that?

If that survives a season of boiling I'll be stunned. Heck, if if it survives a session of boiling I'll be surprised. But the proof of anything is in the doing of it. Let us know how the experiment turns out (and whether you can drink the water you've boiled with the sealant - leaching chemicals out of that stuff at high temperatures is also a concern, though I suppose some of the packaged silicones are rated for food contact - but usually "incidental", like on a countertop seam, not quite the same as being boiled in the pot with it for hours.)

If it is aluminum in a stainless pan, I think the different change in size with changing temperature is going to tear your glue joint open. I think there was also something said about aluminum being attacked by boiling sap on a different thread.

Holding drop tubes in place while soldering is done by flaring the tubes, and letting gravity hold them in place while you solder from the inside/top.

[RileySugarbush]

I agree with Ecnerwal. If I had to choose between the two based on ease of fabrication, the soldered drop tubes win. It is not so difficult and many people with no experience have been successful. Plus there is lots of help available here!

The muffin tin idea is interesting, but I think there are lots of problems waiting for you down that road.

[KenWP]

I went the drop tube way and it may take a while to make it but the effort is worth it in the end.The sap shooting 10 inches in the air due to the tubes is a neat site to see and the fact it boils in minutes compared to the flat pan in the front proves how well it works.I used SS tubing from milking machine lines as it was a 3rd of the cost.Soldering was a learning experience untill I used a anceint soldering iron I paid 2 bucks for at a garage sale.It worked wonders compared to the propane torch.

[CBOYER]

KenWp, what kind of flux you used to solder and where do you get it in Qc ?

[KenWP]

The flux I use is Kester 817. It is the only SS sans plomb solder I can find.I buy it at Rona in Bebee. It is liquid in a white bottle with green label.Works for me at least.

[Logan Cabin]

Another option could be stainless sauce cups from a restaurant supply shop. Found 4 oz cups for $1.20 each, they have a slight conical shape and a lip that would make for an easy weld or solder joint. Best I could tell they are 3" dia. & 2" deep. Not as much area as the copper tubes but cheaper & they're one piece.

[KenWP]

That was my first idea also.I found a bunch of cups for egg poachers that would have worked also.