Steam hood design, input needed

[sams64]

I'm thinking of trying to toss together a steam hood together for better preheating. I'm boiling outside so steam evacuation is not a big deal other than recovering heat. I am boiling on 2' x 3' pan on a home built steel arch. Below is a sketch of what I have in mind. The hood will be 0.040" aluminum as I have that available in large quantities.

http://img.photobucket.com/albums/v64/sammy6477/STEAMHOOD_zps9546e5ec.jpg

The stuff you cannot read are dimensions. I am planning on a 8" stack and 4" gap between the hood and pan. I can make a flaps that drop down and seal the gap, but, want to make sure I can look in and see the pan level.

Any feedback is appreciated. I've studied a bunch of the designs on here and want to make sure I didn't miss something critical.

sam

[Bucket Head]

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That looks like it would work. I'm not sure how exactly your preheater will be configured. I just built one for my current hood. I did mine on an angle so it would have an inlet up high and the outlet much lower. And it would aid in completely draining it upon shut down. I did my last preheater this way and it worked very well.
Steve

[maple flats]

I don't see a catch tray under the tubes, they will sweat big time and with no catch tray with a drain the condensate will fall back into the pan for you to evaporate again. Aside from that, follow what bucket head said. Notice is catch tray, that gets connected to a drain tube and runs out to a bucket for some hot water. As long as your gutters on the hood are water tight, the tray usually drips into the gutter and then the gutter has a drain hose or tube. The gutter really needs to be sealed also because there is plenty of condensate running down the inside of the hood to catch and have an inverted Chinaman's hat shaped funnel under the stack to catch that too unless the tray is big enough to catch everything. The basic idea is to catch every drop of condensate or you need to boil it a second or third time.

[BRL]

Hey Bucket do you have any more pics of your preheater? 1" Copper?

[Jerome]

Here Are some photos of my pre heater, I elected to make a seperate section that sits on my evaporator as it made plumbing it easier. Notice the tray under to catch the condensation.
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[Pibster]

I would keep your hood down tight to the pan, not 4" above. Add a sliding window if you want to check sap levels. It will make your preheater more effective.

[Bucket Head]

BRL,

No, but I can take more. What part of it would you like to see? Or maybe I can answer questions- either way.

Its 1 1/4" copper. The heater is 66" inches long and about 15 1/2" high. Its just under a foot wide. Including the elbows, I figure its pretty close to 51 feet of copper. I tried to get as much copper in as small an area as I could get away with. Since the sap is getting heated passively, you want as much surface area as you can manage.

I know the "preheater vent or no vent" debate continues, just like the Ford vs. Chevy debate. I do not have a vent and my last preheater I built did not have one either. I did not have a feed problem with the last one so I did the same this time. I can add one if need be, but I'm not expecting any problems. Air bubbles rise and all they can do in this type heater is go up.

If you have any other questions let me know.

Steve

[BRL]

I was just curious about the two tee's, but I assume it has something to do with the sap steaming in one line, it has another route through the pre-heater?

[rayi]

My hood was made by Patrick. On the outside is a tube that goes straight up higher than the head tank to prevent vapor lock. So what makes it so the sap does not come out the top if it is inside the hood.

[Bucket Head]

BRL,

The tee's may be a useless experiment, or they may be crucial pieces of the heater- I'm not sure which yet.

I wanted as many rows of copper as I could get in there so I figured I'd use some of the space created by having the heater at an angle. I could only do that by branching off of the original six rows of copper. The other idea was the incoming cold sap would flow a little slower in the six parallel rows than the last three single ones, which would allow more heating.

Now with that said, I have no flow meters or temperature sensors/thermometers anywhere on the unit so i will have no idea if its working that way! Lol. Like I said before, the goal was to have as much heating surface as possible in the space I had to work with. The other goal was to have warmer sap than last year going into the pan, and last year I had no preheater!

Steve