pre-heater with picture

[Maplesugar]

Thinking about adding a pre-heater to my homemade evaporator. I have an under the fire blower and would like to add a pre heater to catch some of my wasted heat. Will this work?:confused:

[Maplesugar]

The evaporator I built is slightly different than others I have seen other people make. I turned my angle iron frame to the outside so I could use a bigger pan. My pan is 30"x48" or 10 square feet. I angled the top edge of my fire brick so the heat would make it to the edge of the stove which is 27.25 inch. I know the angle iron is not as hot at it would be if I turned it inward and over the fire. But it still gets pretty not. It steams from edge to edge and boils pretty good. I have small blower in the ash pan door. The stove has a heavy duty 14x18 grate in the bottom of the fire box. The blow motor really makes a difference in the amount of steam coming out of the pan and kicks up the boil pretty nice. I'm wondering if this pre-heater idea will work or not. My only concern is the amount of draft required to draw enough heat into the box without losing my main chimney's draft. I think this idea could still work without much draft at all to the pre heater box. If it doesn't work with normal hot air rising past a 1" flared inward scoop as it goes by and up into the chimney, I was thinking about just adding a heavy duty pipe that would start in or at the back of the firebox and flow into the pre-heater box. There would be a chimney on the far side of the pre-heater box to create a small amount of draw to bring heat into the pre-heater box. The box would be tapered from 5 or 6 inches to about 1.5 inches with a 2 or 3 inch chimney. I don't need the sap to boil but it sure would be nice to get it steaming. Just trying to use my old pan and wasted heat that is past the sap pan and headed up my chimney and into the sky. Any ideas or tips to make this idea work or work better would be welcome.

[psparr]

Pre heater boxes are never that efficient, but some is better than nothing.

[Maplesugar]

I'm sure this is not a new idea. All I know is the back of my stove is over 600 degrees and that is wasted heat once it reach the back side of my pan. I was just hoping to get 4 more sq ft somewhere near steaming. If I was able to get that pan to steam, I would be happy. I know there is a lot of wasted heat going up the chimney. If it doesn't work, I can weld it shut and go back to where I'm at now. Is this idea a waste of time? Will it cause the main pan to boil slower?

[BreezyHill]

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This is our preheater. I rebuilt it with 1.5" stainless line so it can be easily washed.

Typical sap/concentrate comes from insulated head tank at 34 degrees and hits the float box at 180-185. Hood sends steam to the lower section where the feeder line is and drops into the float box and the steam goes up and out.
condensation out of the preheater is a gallon every 5-6 minutes when boiling hard.
Original it was copper 1.5" but when it corroded thru went to stainless. Stainless is poorer conductor but cleans easier.

I would love to go to a steam away at some point but ll the condensation must be caught for highest efficiency IMO.

IMO any thing to raise the sap's temp in time will likely pay off Build what will work for you and your situation.

Best wishes
Ben