Why Use An Economizer

 May 08, 2023      Jeff Rosenblum

Economizers are incorporated into most rooftop AC units and for good reason! They increase AC efficiency, reduce the runtime of mechanical cooling, and extend the life of the equipment. Plus, they bring in fresh air for ventilation, which helps to displace CO2 and improves the quality of the air you breathe. Economizers also eliminate the fresh air minimum position during unoccupied times.

The main task of an economizer is to check the condition of the outdoor air to see if it is acceptable to use as “free cooling”. For example, if it is 50 degrees outside and the building needs cooling, would it be more efficient to pull in fresh air from outside instead of paying to run the compressor? In most cases, yes, that answer is yes. But what if it was 90 degrees outside? In those cases, bringing in too much of that hot air may create the opposite effect and cause the building to heat up. There is a fine line to understanding where the outside air is no longer acceptable to be used for free cooling.

Economizers work by using a module with temperature and humidity sensors to evaluate the condition of the outside air. If it is suitable for free cooling, the economizer takes the place as first stage cooling. First stage mechanical cooling is then used as second stage, and second stage then becomes third stage. However, if the outside air is not suitable for free cooling, the economizer changes to minimum position for fresh air and the mechanical cooling stages follow the normal set up as first and second.

Minimum position is the setting of the economizer that allows the damper to open just enough that it brings in enough air to displace the CO2, but not too much so that it requires excess mechanical heating or cooling to make up for the temperature difference caused by excess outside air.

If you need technical assistance feel free to reach out to the Famous Supply tech support department.