dropped or raised flu???

[Rosser's Ridge]

I built my arch from scrap to support a pair of 2x4 continuous flow pans. managed 25 gph out of it on its debut last season with only one real problem, the heat caused it to "arch" over an inch once fully hot. I have 2 solutions depending on what type of pan i got with. Part of upgrade includes adding a 3rd 2x4 pan of the flu variety but not sure whether to go up or down? I would think down means more gph and same fluid level through out pans, only problem is im fairly certain design #1 will eliminate "arching" but won't give me the room for dropped flu's, where as design #2 i think will only minimize "arching" but allow dropped flu's. So my question to the maple veterans is what are the pro's n con's n opinions of each

[mellondome]

What is arching? Are your pans warping? And exactly what options are you asking about?

[Rosser's Ridge]

Sorry. The pans are not warping, the arch itself is. The top angle iron was not protected enough from the heat and would bend upward in the middle causing the fluid not to be a uniform depth throughout the pans. I can fix that problem. I plan to make arch longer to accommodate a 3rd 2x4 pan between the 2 continuous pans. Just not sure which flu pan to go with My question is what are the pro's n con's of a raised flu pan and a dropped flu pan.

[mellondome]

Raised flue you can adjust the flue pan level seperate from the syrup pan level. Flues are above the rail so not a big concern of hitting them with wood. But you need 2 float boxes. Drop flue only needs 1 float box. All pan fluid levels are the same. Take care to not hit the flues while fireing ( this is why most drop flue pans are shorter length then raised flue pans for the same arch)

[Rosser's Ridge]

does one perform better than the other (gph)? Is one easier to run than the other. As far as physics go Im leaning toward dropped. puttin the flu's in the heat appears to be a better option than relying on heat to travel up onto flu's. plus i haven't sprung for one float box yet!

[mellondome]

does one perform better than the other (gph)? Is one easier to run than the other. As far as physics go Im leaning toward dropped. puttin the flu's in the heat appears to be a better option than relying on heat to travel up onto flu's. plus i haven't sprung for one float box yet!

There is much debate on the subject. Probably dozen threads on here about which is better. In the end it comes down to preference.

12 ft is pushing beyond the ability of a 2 ft firebox. Why not just drop off one flat pan and replace it with the flue pan?

If you are putting in a flu pan that far behind the firebox ramp, a drop is probably the better option.

[Super Sapper]

If you are going to put the flu pan between the flat pans you will have to go with drop. Putting the flue at the stack end of a 2X12 would not have enough heat left to take advantage of the flu pan. I would get a 6 foot flu pan and go with a 2X10 and get the max out of it.