Homemade preheater pan idea?

[buck3m]

I won't be using a steam hood with my newly purchased evaporator, and it currently has no preheater setup.

I'm thinking of using my old 3 x 6, or an old 3 x 4 aluminum flat pan over the top as a preheater. I'd run the sap in one end, have a slightly low corner to drip the condensation off to the side, and drill a hole in the preheater pan, and put in a spout there to drip the warmed sap into the smokestack end of the main (flat, partioned) pan.

Does that sound like it would work?

If so, how deep should I run the sap in the preheater?

I suppose I'm going to need the preheater pan high enough so I can see the whole evaporator pan, not just the final compartments, correct?

How much efficiency could I expect to gain?

[WESTVIRGINIAMAPLER]

The only problem with that idea in my opinion would be you would be getting about as much condensation dripping off the bottom of the pan back into the evaporator pan as you would be gaining. What I did with my last homemade setup was I had a piece of 1/2 copper tubing that I ran completely thru the firebox and back into the pan. It did not have a float on it, so I manually controlled the flow and at the end of the day, I disconnected the tubing and flushed it with aprox 1 quart of water to prevent any scorching of sugar in the tubing and the heat usually evaporated out about all of the water.

[buck3m]

That sounds like a good idea you had.

The plan with my idea would be to have the low corner of the preheater pan dripping condensation into a container off to the side.

[WESTVIRGINIAMAPLER]

It is cheap and the sap comes out boiling and steam even coming out too, the nyou are even getting a little evap from the preheater. Copper quick connects are easy to connect and disconnect and solder right on.

[Cardigan99]

Buck, check out my post '275 Gal Oil Tank Evap' under homemade equip. We did the same thing i think you are talking about. pan is much smaller, but we were almost bringing it to a boil with 5 gal of sap in it. First pic the pre heater pan is on a log in the right side of the picture. second two pics you can see it on the flat pan by the stack. It made a big difference for us.

[VA maple guy]

Hay Brandon, I'm buying a used Leader 2x6 drop flue this weekend, I was thinking of making a preheater similar to what you described a few posts ago.
How many feet of copper pipe did you put in your firebox. If you have any
better ideas for a preheater for a 2x6 with out a hood I'am all ears. On
my last evaporator, I had about forty feet of 1/2 copper line wrapped around
the stack. It worked pretty good but I though I'd try something different
this time.
Gerry

[maplekid]

buck3m-i have a preheater for a 3 ft wide evaporator it resembles the one on the half pint. its 3 ft long 6 in wide and about 7 inches tall if your interested in it pm me. its got two valves.its ss

[WESTVIRGINIAMAPLER]

Gerry,

Just run a section of 3/4" the entire length of the firebox and see how it works. Never tried it in an evaporator, but copper conducts heat very good and it should heat really fast. Lowes has the copper and brass disconnects for around $ 6 and they work great and seal without any plastic or rubber gaskets.

[RileySugarbush]

I've got to say you are "playing with fire" by running sap feed lines through the flue gases directly. The high temps there, around 1000°, could easily boil the sap in the copper tube very quickly, particularly if you shut off the flow out. You run a risk of having boiling sap shooting out somewhere. Tubes of liquid in hot flue gasses is how steam generators are built, but they are ready to handle steam. Be careful!

I figured out the maximum possible efficiency gain for a preheater once. Assuming the sap was near freezing and it was raised to near 212°, I think the advantage was about 20% over cold sap coming in.

[OGDENS SUGAR BUSH]

Riley Is Right Be Very Carefulthis Is Like Tnt If It Can Build Pressure It Can Explode

Rich

[WESTVIRGINIAMAPLER]

I have done it before and ran it the entire length of a 7' firebox, so I know it works and works good. Definitely can't leave sap in it without a flow as the sap would scorch eventually, that's why I flushed it with water at the end of the day or if I had to shut down temporarily. Small funnel and a quart of water will flush out all the sap quickly.

[maplesyrupstove]

my friend has a 3/4 inch SS pipe 5 feet long loop in his fire box.He has a preheater tank 2 feet square and 10 inches high.Sap used to boil in it and sap would fly in the air and had to be careful not to get burned.Now he has a small circulating pump on it ,now it doesn't boil.Sap is very hot when he adds it to his homemade evaporator.

[JohnM]

I have used Brandon's preheater tube idea on my rig for about 3 years. It uses 3/8 copper tubing and a drain valve on my feed tank(igloo cooler).

Over time the heat takes its toll on the tubing so after a year or two I put in new.

Does a great job of preheating what is usually ice cold.

I use it to keep the level up and boil going it my flat pan.