Method and controller for determining carbon dioxide emissions from a recirculating air heater

A controller for controlling and maintaining a concentration C of carbon dioxide (CO2) in air discharged from a recirculating air heater having a burner, an outside air damper, and a recirculating air damper inversely interlocked with the outside air damper, said controller comprising:

• an airflow measuring sensor for determining an amount of outside air flowing through the outside air damper;
• a position sensor operatively connected to the outside air damper for sensing an outside air damper position of the outside air damper;
• an outside air temperature sensor for sensing an outside air temperature TO of air flowing through the outside air damper;
• a return air temperature sensor for sensing a return air temperature TR of air flowing through the recirculating air damper;
• a discharge air temperature sensor for sensing a discharge air temperature TD of air flowing through the discharge air damper;
• and
• a processor electrically connected to said sensors for recording the amount of airflow through the outside air damper and the outside air damper position value at a plurality of outside air damper positions, interpolating a curve relating the amount of airflow to the outside air damper position for all possible outside air damper positions between a minimum damper position and a maximum damper position, determining an amount of airflow through the outside air damper based on a current outside air damper position and utilizing the curve, calculating a proportion P of outside air brought through the burner based on the current outside air damper position, calculating a supply air temperature TS utilizing the outside air temperature TO, the return air temperature TR, and the proportion P of outside air, determining a temperature difference ΔT between the supply air temperature TS and discharge air temperature TD, receiving a factor K based on a type of fuel used in the heater, and determining the concentration C of CO2 with an equation utilizing the temperature difference ΔT, the factor K, and the proportion P of outside air brought through the burner.