Is there a "Rule of Thumb" for the size the cupola needs to be?

[Machinist67]

Is there any guidelines that tells us the size a cupola needs to be in regards to the size of the evaporator or the size of the steam hood?

[Loch Muller]

My old 2 x 4 vented into a cupola with 12 sq ft of openings and that was more than enough. When I bought my new to me 30x8 evaporator the guy told me that the surface area of the openings should be the same as the size of your evaporator. So I'm going to build a cupola that is about 8 feet long and has 1.5 to 2 foot high openings on each side. If you had a steam hood/ stack venting into the cupola that might change things.

[BreezyHill]

I saw in an old pipeline a reference to steam hood stack size relative to the length of pipe. Our 4x18 had a 24" stack and the 2x6 has a double 6" 6" for front 2x2 and the same on the flue pan hood. They work fine even with a preheater on the flue exhaust.

I would go with nearly the same area as the pan so that you have less chance of condensation in the building but have it designed to be able to close each side by half due to wind or how fast the boil is going. Our old sugar shack got rather cold with all the heat going out the top. The current building will heat up and be very comfortable to work in after boiling a short time.

Ben

[twitch]

When I built my sugar house i had read Or heard some where to double the square footage of your pan That is what i shot for and it works great. It is the same length as my pan but twice as wide. i am going to call it a "Rule of Thumb" .

[maple flats]

I believe I read in the North American Maple Syrup Producer's Manual that it should be the same size as your pans. I made mine that way when I had a 2x6, then I got my 3x8 and with hoods it still works fine and my stacks terminate in the cupola, about even with the bottom of the opening vent doors.
With a good hood/steam stack system you actually don't need a cupola, but one truly improves the image, and when you are boiling it helps draw in traffic so have some product ready to sell.

[red maples]

same square inches as youe total pan size. for example 2 x6 evap should have a cupola of 1728 square inches of opening to allow proper draft as well as ample draft coming in to allow the steam to escape as well as feed the fire!!!