Another newbie question: Preheaters - what are they, and how do they work?

[bussell]

I understand the basic concept, that you want to warm up the sap before it goes into your evaporator pan. But how does one accomplish this?

I'm building a small brick arch. And plan to have no more than 20 taps. Should I even bother with a preheater?

Thanks!

[Haynes Forest Products]

Most preheaters are copper coils that sit above the boiling sap. The incoming raw sap flows thru the coils and get heated by the steam from the pans. Other preheaters get the heat from the arch or stack. The idea as you said is to heat the sap as it comes in. Your using available heat that would other wise be wasted because it has aleady done its job of boiling the sap. You will find hundreds of ways to do this. Some better than others and I can tell you I have had some better than others. One of the draw backs of putting coils of cold sap above steam is it causes the steam to condense on cold coils dripping alot of water/condensate back into the pans (counter productive). So you need to collect the condensate/water and capture it and collect it.

..............................................SEE ITS EASY:o ....................................

[RileySugarbush]

On a small operation it is questionable whether you need one. Actually, you don't need one, but as you start standing around watching your sap boil, your brain starts to boil too, thinking of ways to speed up the process so you can boil more. So you want one!

First, you see that when you add a scoop of cold sap the boil stops. Figure a way to slowly trickle in the sap at a steady rate. A pot with a valve at the bottom works well.

Then you think, what if I could take advantage of that hot stack and heat up the sap in the pot? That leads to copper tubing wrapped around the stack and subsequent problems of boiling sap in the tubing and how to start and stop and make sure it never runs dry....

It never ends....you are at the little spirally part at the beginning of the yellow brick road!


Seriously, if you just figure a way to add sap slowly that is a good first step. The entry level evaporators like half pints have what they call preheaters that are a box tank that sits over the pan and gets warmed by the water vapor rising out of the pan. That is the same thing as the pot, but often the condensate that forms on the outside of these drips back into the sap and you need to evaporate it again. Not good. Make sure that any condensate that collects on the outside of your trickle pot doesn't drip back into your sap pan!

Next year when you get your 2x6 you can think about a steam hood and parallel flow pre heater!

[Jim Brown]

And the year after that you can get your Staemaway to fit on your now too small 2x6 and the journey begins!!

[Pete S]

We are just moving up from a REAL starter.

Right away we employeed a "steamer tray" pan that we held our sap to add to the syrup pan. It simply sat behind the syrup pan, and we kept it full, and very soon would warm the sap to the point you could add and not loose the boil too much.

It is nice as often when we boil, there is a chunk of ice in the sap so it purty cold!

That's just what we did.

Pete

[Grade "A"]

I have my sap going through copper pipes and use the steam to heat the sap. The first year I did not have a steam hood and the preheater did not work that good. Now I have a hood and you can't hold your hand on the sap pipe going into the float box it's so hot (about 180 deg.). So for me using steam to preheat the sap did not do much without a hood.

[red maples]

Last year on the little block rig. I hand only an 18" x 24" roasting pan. so to keep it boiling I used my coleman camp stove and heated the sap until just before boiling and then tranfered it to a pot with a 1/8 " hole drilled near the bottom with a screw as a stopper that was on 2 pieces of 2x2 across the pan and it stayed very hot up there and when the sap went down I pulled the screw out to fill the pan and never stopped the boil. crude but when your boiling like 30-40 GPD (gallons per day) every little bit helps right!!!

[KenWP]

When I got really behind boiling sap I made a extra little stove out of a 5 gallon pail and put a big SS pot on top and preheated the sap on there and then transfred it to the preheater so that it was always really hot. I have no idea if I speeded things up much but made me feel better doing it.

[3rdgen.maple]

My first preheater was a stainles steel pot with a small hole drilled in the bottom after realizing it was emptying faster than I was boiling I experimented with different size nails and just put it in the hole in the pot then set the pot on the back corner of the pan by the stack and it worked out pretty good. Then I realized 50 taps on a 3 by 3 pan on a block arch was a nightmare so I got a 2x6 flat pan setup and tapped 150 and soon I realized................nevermind.