Steam Hood angle

[PeddlerLakeSapper]

This year we are going to add a steam hood with an improved parallel flow pre-heater. The hood form will be an upside down V, ^ shape.

Does anyone know what the minimum angle that could be used and still have the condensation run down and not drip off?

Thanks, Dave

[Haynes Forest Products]

My hood is mostly flat with a small angle at the sides and dont have any condensation that drips off. Are you going to be inside a building or out. The idea is to get the HOT steam out as soon as possible so it doesnt condense. So the higher you go and bigger it is the longer it cools inside the hood the more it condenses.

[maple flats]

I'll bet all hoods condense, just because the hood is below the temperature of the steam. I made my sides straight up for 8", then angle toward the center at about 45 degrees and the top is flat, where the steam stacks are connected. I built a drip tray the full length of the flat to catch any stack condensate as well as the flat top's drips. This tray then drains into the bottom gutter. I made a full gutter for the bottom by using aluminum U channel, 3/4" on each side. It is 1/8" thick stock and I mitered the corners and aluminum soldered them, with one corner having a drain spout. the hood is pop riveted to the inside of thes and all condensate runs out into a bucket for hot water. Once the rig is in full boil I get about 2 gal of hot water an hour. That is all condensate because i do not yet have a pre heater, might for the coming season.

[Haynes Forest Products]

I have a gutter and drains out both sides and out the wall...........didnt need it:) Removed it. I dont get condensate in the steam hood. Its thin aluminum and low profile and it gets hot real hot so I dont get condensate. The steam stack is only 4ft high and ends in a coupla so I dont get condensate in it either.

[sweetwoodmaple]

Ha...I just did a very non-scientific test the other day to try to give me a clue.

I took a flat plate and sprayed a mist on the bottom. I kept tilting the plate while misting the bottom and it seemed that it needed about 15 degrees of tilt before the water ran to the side without dripping off in the middle.

You know what they say about free advice...it's worth what you pay for it. ;))

[PeddlerLakeSapper]

Thanks for the ideas. The mist angle test is what I was going to try, thanks. Just want to keep the hood as small as possible. I am going to have a pre-heater inside, so I know there will be condensation.

You have to learn from you mistakes, but it is easier and faster to learn from others mistakes. Believe me, I have done both.

Thanks for the replies/ideas.

[DrTimPerkins]

...The mist angle test is what I was going to try...

I think you want to try to approximate the conditions inside an evaporator as much as you can. If you can, you should do this test with the water and metal (and air) hot. The results with cold water versus hot water are apt to be different.

Maybe take it in your bathroom and run your shower very hot (don't burn yourself) and let the metal and air warm up, then try misting it with HOT water.

Another way might be to put a smaller piece of metal under the steam coming from a tea-kettle (use an oven mitt)....let it warm up first and build up some condensate, start at a pretty steep angle (water should run down the metal and drop off), then tilt the metal down until you see the droplets fall off the plate instead of run down.

The other way to get the same info....look at catalogs from different equipment manufacturers or visit other sugarmakers to measure the angle on their hoods.

[PeddlerLakeSapper]

Back when we used to build grain handleing systems there was a specific minimum angle that wet grain would gravity flow at. Just seeing if anyone had a number for condensation inside a hood.

Guess I will have to go to the tests and trial and error method.

My goal is to use the least amount of metal, and keep the hood small as possible.

Thanks, Dave

[Haynes Forest Products]

Havent heard yet if we are talking about an outside rig? Thin metal is a key to keeping the hood hot.

[PeddlerLakeSapper]

Semi-outside. We boil under a pop-up canopy. Maybe inside next year.

[Bucket Head]

Outside or semi-outside, the hood will never be as hot as one inside a sugarhouse. Take it from an "outside" guy. The cool ouside air is always cooling the hood, and your pans for that matter. So you will have more condensing action going on with your hood. I would try to make the hood as low as you can (to eliminate surface area) with angles on the sides (to the drip rail/gutter) as steep as you can make them with whatever height, pre-heater, p. heater drip tray, etc., you design. I probably get some drips off the flat top area of mine, but its a small trade-off. The bigger benefit of having a hood outdoors is the fact that the cold breeze is not constantly hindering your boil. Whatever may drip back in is small compared to what your going to gain with the better boil. Take it from this veteran "outside" guy, lol.

Steve