Drop flue pan

[S Culver]

I got into this late in the season last year boiling on a block arch and 3 small pans. I planned on expanding to about 150 this year so I tried to have a 2x2 sryup pan with a 2x4 flue pan made up. So I took some 20 Ga metal to a guy who butchered it all up. then I took it to a second guy to fix it, he even put the partitions in backwards:o Not sure yet if it will hold water yet. During this nightmare I surveyed my woods and I will probibly go to about 300 taps this year with the ability in the future of 500.

Now I have found a shop which can bend up a 2x4 drop flue pan for me. They can use up to a 4x12 sheet 20 ga. They have a 1/2" die and a 1 1/2" for the inside of the flue, but can make up other sizes. What is a good inside dimension for the flue? and is 6" a good depth so I can get some good spacing across the whole bottom of the pan? and is 10" sides good enough with a 3/4" inside lip?

[Haynes Forest Products]

I believe the top of the flue and bottom is dictated by the ability to weld it. I would bet if it was possible to weld the inside and polish it you would see 1/4 inch spaces top and bottom. Cleaning is another problem.

[WMF]

The standard spacing for Leader style drop flue pans is .625" sap space and 1.25" fire space.
I would install a drain pipe connected to the bottom of flues as well.
You can expect your welder to never want to do business with you again after he finishes the pan.

[S Culver]

Thanks WMF That is colse to what they are doing. The channels look more like deep U's that are slightly larger at the top. I went to your site and looked at your new pan. What a thing of beauty, I am not nearly there on needs yet. Now what is the reason for the drain?

[danno]

Take a look at the drain on WMF's pan on the bottom left. Drain it to drain the pan during the season between boils to clean if you choose to do that. Regardless, you will have to drain the pan at the end of the season. You can pump the pan out, but it is much easier to drain.

[Jim Schumacher]

Make a flue drain the last of your priorities on this pan. It is VERY simple to siphon those flues with a small piece of tubing. Having a u shape is great. Especially on the bottom. I think either a V or a U is better on the bottom to divert the flames and heat up into the flues, exposing the fire to the sides of the flues at a more advantageous angle.

[jfroe939]

I'm looking into having a new pan made up and I'm pondering whether to go with a V-bottom or drop flue. Part of my decision will have to do with price obviously but the other element is just how easy is it to clean out that drop flue pan? I saw Welch's pan which has a drain to empty out the flues, but every guy who's boiled sap knows that you also get a crusty, sugarsand build-up that forms tight to the pan just from the heat hitting the sap almost like if you had hardwater with lime build-up. How do you tackle that? If I go with a V-bottom I could probably get something in there and sorta chip that out at season's end, but when you've got limited space to physically get in there like you have with a drop flue, surely that can be a problem. Curious what you think.
A side question... does double the surface area automatically equal double the boil-away given the same heat? Just wondered what those who've used drop flues have found. Want to know what good and bad I can expect. Thanks. Jason

[maple flats]

sugarsand is very minimal if at all in the flue pan, the sugarsand forms most as the concentration nears syrup, in the syrup pan. To clean a flue pan, either drop or raised, there are brushes that do a good job as long as you don't do a sharp long V shape.