Trying to make a preheater

[tuckermaple]

Anyone out there made a preheater? I've tried a couple of times but didn't seem to help that much. I think the condensate just dripped back into flue pan and didn't really gain me much. Guess I need some sort of pan under it. Any ideas would be helpfull.

[vtsnowedin]

There are a lot of good ideas out there and more then a few threads on the subject here on Mapletrader.com. What have you tried and what are you leaning towards this time? Do you want to use the heat in the rising steam or are you planning to use the heat escaping up the smoke stack?

[Haynes Forest Products]

Putting a big tray under the copper tubing wont gain you much. You need to have the steam coming up between the tubes for the higher heat levels. V channels under the tubes that dump into another gutter like channel out the evap works best.

[Jerome]

Take a look at mine in the photos in my signature. You do need a trough under it to catch the drips or you will have to boil it out again.

[tuckermaple]

Jerome it looks like you've done a nice job. How well does this work for you?
I have tried running 3/4 copper pipe six runs across my flue pan with no tray it did heat the sap up a lot but didn't really increase the boiling rate. I had also tried a roll of 5/8 copper tubing but didnt give me enough flow at a full boil. i was thinking of trying to pipe something around the stack this time. Still at the drawing board stage.

[RileySugarbush]

Putting a big tray under the copper tubing wont gain you much. You need to have the steam coming up between the tubes for the higher heat levels. V channels under the tubes that dump into another gutter like channel out the evap works best.


Haynes, that's not really right. I have a full tray under my 6 pass series preheater and I get 180°+ sap. As long as the preheater is in a hood and the hood is full of hot water vapor/ steam, it is going to get to the tubes and condense on them, giving up its heat of vaporization.

I suppose if you had a huge steam stack it could vent the hood too much, but I don't have that problem at all.

[Fred Henderson]

Haynes, that's not really right. I have a full tray under my 6 pass series preheater and I get 180°+ sap. As long as the preheater is in a hood and the hood is full of hot water vapor/ steam, it is going to get to the tubes and condense on them, giving up its heat of vaporization.

I suppose if you had a huge steam stack it could vent the hood too much, but I don't have that problem at all.

I have to agree a hood, tubing and a pan with a drain is what is required. I am seeing temps of 200 degree coming out of my preheater.

[Grade "A"]

I also agree that to get the most out of a preheater you need a hood. I have one full drip pan also and get 190-200 degree sap out of it. I use 1 1/4 copper pipe that runs back and forth 4 time (16 ft), works great.

[Jerome]

tucker
It works great I was getting vapor lock just having it wrapped around the stack and was always worried with residue caramelizing at the end of the boil before being finished. this way with the four 8 foot runs I am getting around 200 out I still get some vapor lock but with the vent in the top I have better control. you do have to have a hood it really decreases the boil time. between the two go for the hood first imho.

[tuckermaple]

Sounds like a hood would be a good upgrade. I guess this may be on offseason project.

[KenWP]

I just finished extending my wrap around preheater by 12 feet. I had 20 plus feet of 7/16 and it wasnt doing the job so I added 12 more feet that I had laying around. If it gives me 10 degrees more I am happy with that. Just need to have it a constant warm and it seems to keep the boil going.

[tuckermaple]

Ken
You just have this wrapped around the stack?

[Maple Restoration]

I just finished making our first pre-heater what a difference it makes we now get a full boil in our back pan, the pre-heater consists of 54' of 1" copper coiled up into a 2' by 4' home made hood with a 6" vent pipe, the sap is hitting the float box at 198 degrees. here are a few pick's.

[KenWP]

Ken
You just have this wrapped around the stack?

Yes just around the stack and I solved the supposed burnt sap problem at the end with a extra peice of tube that I use to run hot water into a pail for wash up afterwards.

[Peepers]

How big of an evap do you have Ken? I'm curious how fast your sap is flowing through the preheater. I'm thinking of doing the "wrap copper around the stack" preheater this year and am hoping that around 20' of 1/2 will work for me. I have a pretty small operation with two 18x18" sink/pans so the flow won't be too fast. For me anything is going to be better than pouring 40 degree sap into my back pan.

Great pics and explanations everyone!

[KenWP]

I am useing 3 of those sinks but two have drop tubes on them. I can beat 10 gallons a hour if I push it and have the right wood. 20 feet of 1/2 inch would give you what you want plus you need to cover it with tin so it heats even better.

[Peepers]

Thanks Ken, sounds good. I just realized I mistakenly got 3/8 instead of 1/2 flex copper so back to the store to exchange it tomorrow rather than get all new fittings.