Many techs know just enough about economizers to bypass them. In this podcast episode, Jerry Eavenson and Bryan talk about the basics of what an HVAC economizer is and how it functions.

Economizers typically work on the air side of package units and help pull fresh air into a structure. Economizers are almost exclusive to commercial HVAC. Climate also plays a role in their usage; you will not find many economizers in hot and humid places like Florida.

An economizer is generally an energy-saving device that brings fresh air into a building if it is of a higher quality than the return air. These economizers determine if the outside air is better than the return air via enthalpy controls. Enthalpy controls evaluate the humidity and temperature of the air.

When you set up an economizer, you can easily go wrong if you don't understand the sensors that are involved in the setup. Many economizers have dry-bulb or enthalpy sensors (wet-bulb), and these sensors are not interchangeable. You typically have to know the model number to differentiate the two types, but the model information is readily available on the internet. Typically, your differential set points will depend on your climate zone. You may come across fixed-enthalpy or differential controls.

When it comes to economizers, acquiring documentation is the best move. As with all types of HVAC equipment, reading the manual is the key to understanding what an economizer does. Jerry recommends identifying the controls, sensors, and functions of the equipment. Economizers may vary greatly across models within a manufacturer (let alone across manufacturers).

Jerry and Bryan also discuss:

• Heat loads of commercial spaces
• Variable frequency drives
• Sensors
• Economizer setup
• Honeywell Jade
• Cooling stages
• Controls
• Dehumidification-only application possibilities
• Return duct sizing
• Climate zones

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