Here's a comparison of the standard Afco heat exchanger (PN AFCOHE; $399.99) and the new dual-fan unit (PN AFCOHEDUAL; $669). As you can see, the new dual-fan unit is a bit taller than the standard dual-pass unit to accommodate the twin 10-inch Spal fans. To be exact, the dual fan unit is 113/8 inches tall, 26.25 inches wide, and 2 inches thick. The standard unit is 9x22.44x2 inches. As a result, the dual-fan unit yields 96 square inches of additional front-face area (298 versus 202 square inches.) over the standard dual-fan unit. Of course, the dual-fan unit also holds a lot more coolant than the stocker-170 percent more-which helps shed heat as well.