Abstract: A controlled atmosphere incubator having an interior chamber surrounded by a heated water jacket. A glass access door of the chamber is directly heated by a clear, electrically conductive coating. The door is sealed against the perimeter of the opening by a readily replaceable gasket and is field reversible due to unique hinge mounting assemblies. An easily accessed blower assembly is located within the chamber and includes a HEPA filter readily replaceable by the user from within the chamber. A filtered air exchange system is provided for limiting the maximum level of humidity in the chamber. The incubator control maintains constant power output from the blower motor so that the heat output of the motor is also constant. A voltage compensated temperature control is also provided for the heaters associated with the water jacket. Compensation for environmental conditions inside the chamber is also provided by the control for producing more accurate readings of carbon dioxide levels.