tuolumne
03-10-2012, 06:59 AM
I would like to make my own pans over the next few years, and this Mason style flue pan seems much more manageable than a drop flue style. I will list some pros and cons as I see them, I would appreciate any input from those who have boiled on both styles. I am considering copper pipes for better heat transfer and I have some on hand. Compared to a drop tube style this horizontal tube pan would have less welds, easier to clean, no end caps to buy, and easier to drain. On the other side it has more length of pipe (cost but more surface area) and could not use recycled pipe as readily (48" lengths vs. 7").
Here are some numbers to compare this to a typical (easy to find around here) flue pan: 7 flues at 7-1/2" deep. Running sap at 1" above the channels, I figure about 6192 square inches of surface area to 4320 cubic inches of sap. For the horizontal tube style I show (using 24 total tubes at 1-1/4 diameter as shown on the right) would have 7488 square inches of surface area to 6096 cubic inches of sap at 1" deep. The ratio of surface area to sap volume is slightly better (1.43 vs. 1.23) for the drop flues, but mine would have the advantage of copper heat transfer over 2/3 of the surface area. Also, I could do it with 40 copper tubes like the layout on the left which would be significantly more area.
This is where I have some questions. How close is too close for the tubes based on the way sap behaves when boiling? In the 40 tube scheme, there is a bit under 1/2" between the tubes. In the 24 tube scheme there is an inch between the tubes. I could also do something in between, or stagger the tubes, but I felt that it would be easier to clean with them lined up vertically. Would it be better to leave the big spaces horizontally or vertically...opinions please. Modifying the scheme on the left, I could do 30 flues (bigger vertical spaces) or 32 flues (bigger horizontal spaces. I could also change the overall depth of the two drops up or down. I could also change to 1-1/2" or 2" copper pipe if that made sense, although I don't have as much of that on hand.
With the 24 flue version I would have about 56 square inches of flue area if I brick to within 1/2" on bottom and sides. This seems like plenty with forced AOF/AUF setup. Any comment? I'll leave a door on the rear to easily brush out the tube flues mid season if needed.
Lastly, I am trying to make the most of a 4x8 sheet, so I made some rims at the top. What is a good geometry for these? The pan shown is 2' wide overall, with 7" deep main channels, a 1" flue in the center, and 2" on either side to clear the brick where it projects beyond the rails. The sides are 18" high and the center divider is 15" high. Do these seem like good numbers?
Lastly, where should the hole be located to pass sap from one side to the other? Yes, I know in the rear, but should it be at the bottom of the 2 channels, somewhere higher, or most of the depth at one end?
Thank your for input....I have never seen, let alone boiled on a horizontal tube flue pan.
5619
Here are some numbers to compare this to a typical (easy to find around here) flue pan: 7 flues at 7-1/2" deep. Running sap at 1" above the channels, I figure about 6192 square inches of surface area to 4320 cubic inches of sap. For the horizontal tube style I show (using 24 total tubes at 1-1/4 diameter as shown on the right) would have 7488 square inches of surface area to 6096 cubic inches of sap at 1" deep. The ratio of surface area to sap volume is slightly better (1.43 vs. 1.23) for the drop flues, but mine would have the advantage of copper heat transfer over 2/3 of the surface area. Also, I could do it with 40 copper tubes like the layout on the left which would be significantly more area.
This is where I have some questions. How close is too close for the tubes based on the way sap behaves when boiling? In the 40 tube scheme, there is a bit under 1/2" between the tubes. In the 24 tube scheme there is an inch between the tubes. I could also do something in between, or stagger the tubes, but I felt that it would be easier to clean with them lined up vertically. Would it be better to leave the big spaces horizontally or vertically...opinions please. Modifying the scheme on the left, I could do 30 flues (bigger vertical spaces) or 32 flues (bigger horizontal spaces. I could also change the overall depth of the two drops up or down. I could also change to 1-1/2" or 2" copper pipe if that made sense, although I don't have as much of that on hand.
With the 24 flue version I would have about 56 square inches of flue area if I brick to within 1/2" on bottom and sides. This seems like plenty with forced AOF/AUF setup. Any comment? I'll leave a door on the rear to easily brush out the tube flues mid season if needed.
Lastly, I am trying to make the most of a 4x8 sheet, so I made some rims at the top. What is a good geometry for these? The pan shown is 2' wide overall, with 7" deep main channels, a 1" flue in the center, and 2" on either side to clear the brick where it projects beyond the rails. The sides are 18" high and the center divider is 15" high. Do these seem like good numbers?
Lastly, where should the hole be located to pass sap from one side to the other? Yes, I know in the rear, but should it be at the bottom of the 2 channels, somewhere higher, or most of the depth at one end?
Thank your for input....I have never seen, let alone boiled on a horizontal tube flue pan.
5619