Preheater for block arch

[Bemis]

I tried the typical preheater design last year. 20 feet of 3/8" tubing wrapped tightly around the stack and shielded/insulated. It worked okay, but I really only got 30 or so degree of temperature rise. I'm moving up to a 4x2 pan this year, so I'm hoping to do a little better on the pre-heater.

Here's my idea. I'm hoping for comments. Maybe I'll scan in a sketch tomorrow.

I have a 6" stack coming out of the arch. I'm thinking I'll install a 6" wye near the base of the stack to divert some flow. I'll have a damper on the main stack and on the wye. I might reduce it to 4" after the wye. My pre-heater coil would be installed inside the duct of the stack bypass. I should be able to roughly control flue gas so as to not overheat the coil to the point of boiling at the flowrate I'm running. I'd monitor sap outlet temperature and adjust as needed to get closer to boiling.

I think there will be no problem in getting enough heat. I'm only worried about vapor lock if things get out of hand. I good damper strategy should help that.

Anyone tried this before? Any thoughts.

[Bucket Head]

Give it a try! It sounds like it would work. It does'nt matter if anyone else has tried it. This site is full of guys who have tried something (myself included) and shared what they learned. Wether it worked or not.

Get a magnetic stovepipe temp. gauge so you have some idea of what the temp. is in the coil area. Its bound to gain temperature over the other set-up. I would'nt try to get close to the boiling point however. You don't want that. Most of the preheaters out there get between 180-200 pretty easily. Anything over the original temp. increase would be a step in the right direction. All the block arch guy's on here will be eager to hear the result's!
Good luck.

Steve

[WESTVIRGINIAMAPLER]

The last flat pan setup I had was 3x7 and I ran a piece of 1/2" copper tubing from the rear of the firebox out the side of the firebox next to the front of the pan. The sap came in so hot it would shoot out of the pipe. I had a 150 gallon feedtank sitting above the pan and I controlled the amount of flow with a manual valve. Never had a problem with vapor lock and at the end of the boil, I unhooked the copper with from the tank and ran about a quart of just regular water thru it to flush it out good. Worked great and never had any problems with any syrup scorching in it and the sap was already boiling before it hit the pan. I brought it up over the side of the pan and the end where the sap came out was pointed down into the pan, so it was never a burn hazard.