Method for controlling an economizer

A method of controlling an economizer, comprising the steps of:

• operating a conditioning unit in a heating mode to provide conditioned air to a plurality of zones, said unit having an economizer operable to allow variable amounts of outdoor air into said unit;
• sensing a first temperature representative of air returned to said unit from the plurality of zones;
• sensing a second temperature representative of the outdoor air;
• and
• modulating the economizer to increase the amount of outdoor air entering said unit when the first temperature rises above a heating setpoint, the second temperature is lower than the first temperature, and said unit is operating in the heating mode.

A method of controlling an economizer, comprising the steps of:

• operating a conditioning unit in a cooling mode to provide conditioned air to a plurality of zones, said unit having an economizer operable to allow variable amounts of outdoor air into said unit;
• sensing a first temperature representative of air returned to said unit from the plurality of zones;
• sensing a second temperature representative of the outdoor air;
• and
• modulating the economizer to increase the amount of outdoor air entering said unit when the first temperature falls below a cooling setpoint, the second temperature is greater than the first temperature, and said unit is operating in the cooling mode.