3/4 or 1/2 in preheater

Hi everyone. I've been playing with the sap/syrup thing since i was 15 or so,going from mom's canning pot in the kitchen to a 40gal stainless pot boil outside for a few years. when I was 37 I bought a 18 x 48 used evaporator with a stainless hood. Worked great for the first year, I made enough to pay for it. the following fall we got hit by a hurricane and it blew most of my tree's down. So....I've been thinning and culling my new area for the last 6 years. Finally last year and 44 yrs old I made some syrup again, now I have too much sap for my little evaporator.
I want to make a preheater, Ive found one on here that I like. It is made from 3/4 copper. the headers are 3/4 also. So, here is the question. would it be better to make my header out of say 1" and the rest of it from 3/4? I'm just wondering with the design of this the inline comes in and flows down to the header, then it travels up the 3/4 (5 pipes) to the top header and from there exits to my float box. But wouldn't the 3/4 pipe closest to the exit on the header get the most action? then i wouldn't get the full benefit of the hot sap. the other pipes would be hot but may not get to the exit pipe before the one that is closest.
Sorry for the confusion. I hope that I have explained this ok.

I would stick with all 3/4" pipe. Make it as long as possible and use as many runs in length as possible. The inlet header needs to be mounted a few inches lower than the outlet. This should prevent your sap from "short circuiting" and going the shortest route. You can also take the outlet off the far side of the upper manifold and route it to your float box. You will also want to capture the condensate so you don't boil it again. I believe a hood and preheater combo only increases efficiency by 5-10%. Hopefully you don't have too much sap:)

Maritimer,

I agree that you need to stay with the 3/4". I built my preheater out of 1/2" diameter copper. It is continuous flow with 22' of run in the matrix, the problem being is that my evaporation rate on my rig is too efficient for the available flow from the 1/2" copper. There is too much friction loss due in the system to match the flow needed. It sounds as if your design is not a continuous flow, it instead involves the header design that most commercial rigs do, so that may eliminate it. Just some points to ponder. Good luck.

3/4 i went 1-1/4 and think to big not enough heat transfer through the pipe

I have a 2x6 with 1/2 inch pipes. It works for me and gets the water to around 160

I made one as you are describing out of 3/4 and it worked o.k now I have one made out of 2" copper pipe its continuous flow and gets hot as hell I think theirs 30ft of pipe in it. i get 20+ gallons per hour better on a 3x12

I just made this preheater and hood. 3/4 seems as though it will be sufficient for flow assuming you have enough elevation in your head tank. I went with the manifold design because it reduces the chances of vapor locked sap and an unexpected loss of flow.

Attachment 6332Attachment 6333Attachment 6334Attachment 6336

Quote:

---

Originally Posted by Tucker08

I just made this preheater and hood. 3/4 seems as though it will be sufficient for flow assuming you have enough elevation in your head tank. I went with the manifold design because it reduces the chances of vapor locked sap and an unexpected loss of flow.

Attachment 6332Attachment 6333Attachment 6334Attachment 6336

---

Even though you made a manifold you should still add a vent to the top manifold, they can still vapor lock if the float stops taking sap. I use a tap for and ice maker, it attaches to the pipe and has a sharp point on a screw that will pierce the pipe, then you back the screw out a bit and there is a rubber seal that fits in. It vents through the top of the hood with a piece of copper tube abd a compression fitting at the bottom. I added a piece of sap line so I could see when it vented sap.

Quote:

---

Originally Posted by nymapleguy607

Even though you made a manifold you should still add a vent to the top manifold, they can still vapor lock if the float stops taking sap. I use a tap for and ice maker, it attaches to the pipe and has a sharp point on a screw that will pierce the pipe, then you back the screw out a bit and there is a rubber seal that fits in. It vents through the top of the hood with a piece of copper tube abd a compression fitting at the bottom. I added a piece of sap line so I could see when it vented sap.

---

Thank you for the tip. I did solder in a threaded fitting on one of the corners so I could add a vent. I did get a vent that holds liquid and allows vapor to pass, but the more i learn from good people like you the more i realize i should go the simpler route and make a threaded fitting to go through the top of the hood. Help me understand your sap line and visiblity idea. you see sap in it at all times?

Quote:

---

Originally Posted by Tucker08

Thank you for the tip. I did solder in a threaded fitting on one of the corners so I could add a vent. I did get a vent that holds liquid and allows vapor to pass, but the more i learn from good people like you the more i realize i should go the simpler route and make a threaded fitting to go through the top of the hood. Help me understand your sap line and visiblity idea. you see sap in it at all times?

---

No you usually don't see sap it it unless the sap in the preheater gets really hot. My thermometer on the preheater will max out at 200 and i'll peg the needle past that then I get sap up through the vent.

I now have the preheater sitting on top of the flue pan. I have a hood built, but I want to run it for a little while without it...just until I have learned the rig a bit. I have a drip tray bent up as well with a piece of angle on the bottom that I will take the condensation and run it out of the hood and into a bucket. I am not sure this is typical or not, but I also soldered a "oh Crap" valve onto the inlet side so I can dump sap in there fast bypassing the preheater if needed. I have it pitched upward about 1.5 inches toward the back. Is that sufficient?

Attachment 6688