Preheat question - - Manifold or Stack?

I have a question about what will give the most heat transfer? I currently have no hood, and no preheat. I do have a 3/4" line coming from my tank that goes through a filter and then into my float set up. My arch is 4*12.

I have a 30-40' piece of 3/4 soft copper I want to install after filter and before float box. Should I wrap around stack, or build some sort of Manifold? I have some SS I could suspend above the pipe, and certainly I can put some sort of tray under it.

If I go with the stack, I don't think I would be able to wrap it more than 2-3 times. And if I go with stack should soft copper touch the stack or should I suspend away .5 ". I'm thinking that with the short piece of copper that vapor lock won't occur.??

I am not looking to spend money on more SS sheet material. However I do want to get my sap as hot as possible before it hits the pans.

Thanks

I think for a manifold pre heater to work your gonna need a hood. I don't know about trying tio get the 3/4 tight around the stack. I used 40ft of 3/8 for mine, way to small for your rig. Here is a shot of mine.

http://i2.photobucket.com/albums/y26...ps25333b0c.jpg

http://i2.photobucket.com/albums/y26...psce6dc74f.jpg

325abn,
How does your wrap around the stack pre heater work? Does it get the sap up around 200 degrees? Do you have any issues with vapor lock?

I will let you know hopefully very soon. Have not had a chance to boil yet this year. I had a simular setup down at my other place and it worked well. There is a vent at the top of the feed line, after the feedtank and before the stack. The key is to make sure the line is empty or flowing fast enough to prevent boiling. Trail and error is the word of the day. I think this is going to work well with the insulation and the shielding. I should get good heat transfer.

I would like to hear how well it works. What size tubing did you use and how many wraps? I'm guessing that is a 6" stack?

Sorry, off the subject but could someone tell me where to get the white insulation in the pic?:lol: thanks

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Originally Posted by Kacey small scale maple

Sorry, off the subject but could someone tell me where to get the white insulation in the pic?:lol: thanks

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Most sugaring supply company's have it. Most places have it in 2 inch widths. And 2 ft widths. I know places like bascom sell it by the square ft. Very inexpensive.

That is 6" stove pipe with 40Ft of 3/8 copper. I bought the roll at Bascoms.

325abn, Thanks that is what I was looking for. I'm going to try what you did and I'll let you know how it works. You mentioned a vent between the storage tank and the stack. What will that entail? Also, I was wondering since you said you used this set up before how the copper holds up during cool down period when no more sap is coming through pipe and there are a bed of coals still keeping the stack 2-300 degrees. Do you leave sap in the line so it can't melt? Or do you have to keep sap coming in until the entire rig is cool? Thanks

The vent is just a "T" with a length of tube extending above the feed tank. I burn oil so I do not have the cool down issue. Turn off the switch and thats it!:) I do make sure the pre heat tube is empty so it will not freeze.

I used a system like that. When out of sap or shutting down, you must substitute water for sap and divert the water outside of the pan. Water is just used to cool the tube.....

Which way do you run the sap through the preheater? In the bottom of the coil and out the top or in the top and out the bottom?

I went from the feed tank into the bottom of the coil and out the top and into the pan. When I substituted water, I slipped a length of hose over the copper tube and directed it over the side and into a pail. As the feed tank got low on water, I dumped the pail back in and used the water again. Just need enough flow to keep the coil cool.

Is that the flow of sap with a preheat in a manifold/hood setup, from bottom to top? I'm guessing you get more heat transfer with pushing it up. However I would be more concerned with it air locking. Is the advantage in feeding the bottom or the top first?. I think safe money is on (top to bottom) for gravity flow, however it may get better effect in (bottom to top).

I had a new idea about the preheat that will solve my cooling of the pipe problem. I am going to bend the pipe into a kids straw shape with several bends and press it against the back of my stack holding it tight with SS wire. Then when I am out of sap for the evening I can undo the SS wire and remove pipe away from stack. Water isn't always certain at my sugar house. Pipes freezing etc. and getting it into my tank is even more of a problem. So being able to undo it each boil will be handy.

I feed it from the top.

I think that is the way I am going to go to be safe.

325abn....

Is that just a sheet of tin you wrapped around your copper coil, or is it stainless - or some other material? Also, how did you join the seams?

no sap flow means too much thinking of the next project.

thx.

Its just a piece of 8" gal duct work. I pulled it tight around my coils and used sheet metal screws to hold it in place. I also put a piece of insulation both at the top and the bottom.

OK thx.

Have you had a chance to run your coil yet? If so, anything you would tweak?

Quote:

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Originally Posted by 325abn

Its just a piece of 8" gal duct work. I pulled it tight around my coils and used sheet metal screws to hold it in place. I also put a piece of insulation both at the top and the bottom.

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That is pretty much the same thing I did and I found it works very well. The sap come out at 115

I use a tank preheater that came with my Grimms setup. I am waiting for your results.
When the fire burns down I shovel the coals out of the arch. This helps cool things down faster.