How much exhaust stack and draft do I need for the heater to burn properly?

The recommended draft for the Trekker is between .030 -.045 inches water column. This is measured 18” (45cm) up the stack and before the draft regulator. The minimum flue stack height is 6 to 9 feet (1.8 – 2.7m). The recommended draft for the Expedition and Prospector is between .040 -.060 inches water column. The minimum flue stack height of both is 9 to 12 feet (2.7 – 3,6m).