Another Preheater Design - Hopeful for 2014

[workinprogress]

I am trying another preheater design. My concern with a continuous pipe setup (wrap around stack) is the sap moves too fast through the preheater and never gets enough time to heat up. Also I wanted to be able to remove the setup. My thought was to create a preheater similar to a setup with a hood where multiple tubes run parallel pipes to slow the flow of sap.

Last year I went with a system of 6 parallel 1/2 copper pipes (24 inches each). I covered the setup with metal to hold the heat in. The cold sap comes in at the bottom of the setup and slowly moves up the 6 parallel pipes before going out the top of the setup. This slowed the sap though the pipes. In the end I was getting about +30 to 40 degrees rise. Which I thought could be improved. I had placed a venting pipe with valve on top if a vapor lock occurred but I never had a problem. When done for the night or out of sap I could quickly lift and remove the setup from the arch.

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This year I am in the process of modifying it. I still wanted to keep the setup removable. I took the set up from last year and placed some 90 degree elbows in top and bottom pipes. This allowed me to wrap it around the chimney (3 sides) but still allows it to be removed from the chimney. I was also able to add 2 more 24 inch pipe sections so I end up with 8 parallel pipes. I am still finishing some of the set up and need to add the last pipe to feeder hose. In the end I will wrap the setup in metal to help keep the heat in. Just like my setup last year the sap flows into the bottom of the preheater and then moves up the tubes before leaving the preheater at top.

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Hopefully I will get some sap this weekend to get the set up a test run.

[SeanD]

I made the same thing this year only my pipes run horizontally. My feed line and vent are connected with unions so that's how I can disconnect at the end. While the temp rise is moderate, the biggest benefit for me is that I could remove the preheater pan that used to sit on top of my back pan.

Nice job and clever idea turning around the stack. My first attempt was with copper coil modeled after Johnny Cuervo's. It wasn't pretty.

Sean

[mantispid]

I wonder how difficult it would be to form the copper piping in a tight spiral around the stack...

[steve J]

I am a little confused I see were the sap comes in from head tank but why does it not go straight down to the spout at the pan what's forcing it to flow thru the other pipes?

[maple flats]

Try looking at member Johnny Cuervo's pre heater. He gets temps between 180 and 200 feeding the pans. His is adjustable too. I wonder how much heat you will exchange with some of the tubes several inches away from the hot stack. Is there a feed line we can't see in the picture, putting cold sap in at the bottom on the back side?
With your neat design for a transition on your base stack, you might be more effective if you get some soft copper and shape it to fit the curve, then if it gets too hot you can raise it a little so sap won't boil in the pre heater. Many of those who wrap the stack end up boiling in the tubing.

[workinprogress]

Actually you don't see where the sap comes in. I still have to add the pipe. In short sap will come from the bottom right of the preheater. So it feed the preheater from the bottom.

[workinprogress]

I was able to get the feeder pipe onto the preheater this evening. The copper pipe coming out to the bottom right will be connected to a 100gal tank outside the shed using a hose (hose not on yet).

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The sap comes in and moves along the back of the arch and feeds the bottom of the preheater.

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Sap will slowly rise up the 8 vertical pipes and then run to the pan. The upper valve (top left) is to vent if needed and the lower left valve is to control the flow.

I have a few supports to add and then I will cover the pre heater in metal (most likely 8 or 10 inch stove pipe.)

Weather forecast for the weekend/Monday looks good for possible run.

[workinprogress]

After a somewhat short but OK sugaring season I wanted to pass along the results of the preheater. Typical outflow temperatures ranged from 80 to 115 degrees into the pan. Sap leaving the head tank was generally running low to mid 40's. The setup was very easy to remove and install on the stack. If I had to do it again I would think about 3/4 inch copper pipe instead of 1/2.

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