HVAC Device: Economizer

IMPORTANT: see Imperative vs. Reactive Code Base

The General Idea

The Wikipedia article on economizers is a good starting point.

Why Enthalpy Economizers Don't Work explains the role of humidity (though the title is a bit misleading).

DZ Implementation

Definition

An economizer is a device that will prevent the main HVAC device from switching on, and instead, turn itself on when conditions allow.

Operation

The economizer is connected to a zone.

• When the ambient temperature is more than changeover delta from the zone temperature, the economizer shuts off the HVAC and turns on.
• When the zone temperature reaches the target temperature, the economizer turns off.
• Zone setpoint plays no role in economizer operation.

Example (Cooling Mode)

• Setpoint 27°C, changeover delta 1°C, target temperature 22°C.
• Ambient 30°C, zone temperature 29°C: HVAC takes care of cooling.
• Ambient 28°C, zone temperature 29°C: economizer shuts off the HVAC and starts taking care of cooling.
• Ambient 22°C: economizer shuts off.

Configuration

Stay tuned.