Parallel Flow Sap Pre-Heater
The Parallel Flow Sap Pre-heater is a set of copper pipes installed over the flue pan. Sap travels through the pre-heater before it enters the evaporator's flue pan. With a parallel flow pre-heater, sap will be warmed to between 160-185º Fahrenheit.
The unit comes complete with a drip pan, to catch all the condensed water that forms when the steam from the flue pan warms the cold sap. For maximum performance, a steam hood is needed to hold the steam around the preheater. Pre-heating your sap will increase the performance of the evaporator by 15-20 percent without any additional fuel or labor. Also available upon request in stainless steel.
Copper vs. Stainless Steel
Copper is a much better conductor of heat than stainless steel and therefore is a more effective material to use when pre-heating sap. Because of copper's conductivity, the heat applied to it spreads very evenly over its surface, and the heating of sap is more even throughout the pre-heater. In order to achieve the same increase in performance from a stainless steel pre-heater, we must double the heating surface by adding additional pipes for the sap to travel through.
Why Parallel Flow?
As sap is pre-heated, there is a chance that vapor (steam) may be generated. That vapor can create a blockage in the pipes of a pre-heater and stop or slow the sap from flowing through. With a series flow design, that blockage would stop all liquid from reaching the flue pan, and could cause the evaporator to run to shallow and burn if it is not noticed right away. With a parallel design, the sap flows from one end to the other through a single pipe. Each pipe carries it's own volume of sap, so if one pipe is blocked or slowed by vapor, the other pipes will still flow. This system also comes with a vent tube that allows the vapor to be vented off, drastically limiting it's impact on flow.