Cementitious board drying system and method for making cementitious board with dryer

A system for manufacturing a cementitious board, the system comprising:

• a conveyor, the conveyor configured to convey the cementitious board along a machine direction;
• a dryer, the dryer including a housing, a heating unit, an exhaust stack, and a heat exchanger,
• the housing defining a board inlet, a drying chamber, and a board outlet, the board inlet and the board outlet in communication with the drying chamber, the board inlet arranged with the conveyor and configured to receive the cementitious board therethrough, the drying chamber including an entry section and a main heating section disposed downstream of the entry section along the machine direction,
• the heating unit configured to generate heated air and to move the heated air through the main heating section of the housing to promote convective heat transfer to the cementitious board,
• the exhaust stack in communication with the main heating section for expelling air from the main heating section out through the exhaust stack, and
• the heat exchanger operably arranged with the exhaust stack and the entry section of the drying chamber and configured to transfer thermal energy from the exhaust stack to the entry section.