Steam hood questions?

[Chris Zeger]

I will be making syrup this year in my shop we just bought a new house this summer that has a 30'x40' shop. There is already a woodburner in the corner of the shop I plan on just hooking my evaporator up to it and want to build a steam hood to get rid of steam the ceiling is plywood. Does anyone have any plans or ideas I'll be using a barrel evaporator. I should also mention I work on a fab shop so building something is pretty easy.

[psparr]

If it will be a tight fitting hood, make sure it has a drip channel. You could also go as cheap as a wooden frame covered in plastic suspended over the pan.

[maple flats]

I've seen hoods running from wooden strips framing the whole evaporator and plastic sheeting stapled to it (the thing overhung the pans about 6-8") to fancy factory made.
I've always made my own in the past, using natural finish aluminum sheet. The first was made of aluminum flashing, my next one was made from 3x8 sheets of flat aluminum. On both I used U channel pop riveted on the bottom edge as a gutter to drain off condensate. Be sure to add a catch tray with drain to keep condensate dripping down from the steam stack from going back into the pan.
On my current pans I was originally going to make a new hood, because the manufacturer had quoted me $1950 for a new one back in 2011, but when I went to pick up the new pans, they asked if I wanted a demo hood. I looked at it, and there were 3 small, barely visible dents in it. I asked the price, it was being sold for $800 and it was SS. I then loaded that onto my truck too. To say the least, my short bed F250 super cab was full, including as many extras as I could fit in the back seat.
This IS nicer than any I made (and I had been a siding trim fabricator for a few years), but when it comes right down to it, they all performed the same task and did it well. If you make one, add at least one access door on each side (mine were always sliding doors, using S channel I had mad on a bar folder, one part snug, and the slider channel loose) and my factory one is also sliders, but they (2 each side) slide in a SS channel welded inside the hood. I've also seen hinged access doors used. I now have 2 steam stacks at 15" diameter and each has a shallow funnel suspended under the stacks, 18" OD and then a drain about 3/4" and I then channel the condensate to the gutter that goes all around the inside edge of the hood.
If you make one, make it tall enough to add a pre-heater in the hood later if you decide to increase the boil rate, it helps.

[hodorskib]

Here is a link to one that I built for my 2 x 3 flat pan which used to be on a barrel stove. You could modify for your needs. It using the pan for support so you don't need to suspend.

https://sites.google.com/site/mattatuckmadnessmaplesyrup/outdoor-steam-hood

[smokeyamber]

On the question of materials for a hood, any issues with using galvanized duct sheetmetal ?

[Haynes Forest Products]

Galvanized might disqualify you from retail sales. Sheet aluminum is cheap and will last for ever. Keep in mind hoods dont need to be monstrous contraptions that stick up 4'. Having room for a preheater is important. Ease of removal is one of the most important feature I can think of is because you will not clean your pans if you cant get the hood up and away. My doors 2 on each side are just simple flat covers with a lip that let them lay in place. You wont be scooping out foam but you will need to defoam thru them.

[maple flats]

Do not use galvanized. I have made hoods for 3 of my evaporators in the past, the first 2 (a 2x3 suspended when boiling, but it was lowered when I shut down, and a 2x3 tight fit on the 2x3 flue pan on my 2x6 evaporator that one set tight on the pan0. Both of those were made of aluminum roof flashing. The third one I made to fit my 1st set of pans on my 3x8. It had a 3x6' flue pan and a 3x2 syrup pan. I made a single hood that was 8' long, the 6' sat tight on the flue pan and the portion over the syrup pan was up about 16" or so. For that one I used the thinnest aluminum sheet I could buy, which was thicker than flashing (.025") and I had to beef up my aluminum trim brake to bend it. I used to do siding and had a 10' trim brake, which was fine for coil trim stock, but when I tried to make a bend in the 8' length of .025 aluminum, the main C clamps tried to spring. I devised a way to further clamp the Main C clamps and it worked then. If you have an aluminum brake you may need to do something similar, if you have a heavy sheet metal brake it will be fine like it is. I used 1x1x1 aluminum U channel for the gutter and welded miters at the corners to catch the condensate that runs down the inside, at 1 corner I made a drain the stuck out about 8" and drained into a bucket. The U channel was pop riveted to the bottom of the hood. On the elevated part over the syrup pan also had a gutter the same, and that drained into the lower gutter.
When I bought new pans I was quoted $1900 for the hoods and stacks (2@15" each for steam) I decided I'd make new again, but when I got to the factory they asked if I wanted a 1 yr old demo set that had some minor dents. One look and I asked how much, they said $800 with the stacks and we loaded them into my truck too, all in SS. The truck was full to capacity, for sure, in fact one 15" stack wouldn't fit and a guy from the factory delivered it to me on his way south to visit his brother about a month later.
The point is, if you have the equipment you can make a nice hood, I just folded the edges and pop riveted them, I made sliding doors, one on each side that slid in loose bent S cleat.

[theschist]

I can fab a hood out of aluminum, but what about the exhaust pipe? I can only seem to find it in galvanized. Will that make a difference?

[wiam]

I can fab a hood out of aluminum, but what about the exhaust pipe? I can only seem to find it in galvanized. Will that make a difference?

I used similar to this https://m.lowes.com/pd/Lambro-6-in-x-96-in-Aluminum-Semi-Rigid-Flexible-Duct/3240913 On my 2x6. Found an aluminum horizontal exhaust vent that I ripped the louvers off for the adapter on the hood.