An economizer is an energy-saving device that is installed in a building's ventilation system. It helps lower energy bills by reducing the amount of heating and cooling required for a building. Economizers are available in different types, such as dry bulb, subcooled, and waterside models. These devices have their own advantages and disadvantages.

The first step to selecting the best dry bulb economizer is to determine the type of system to use. This process involves measuring air temperature, which is a limiting factor for energy efficiency. Then, determine the appropriate setpoint for the economizer. There are two basic types of economizers. Fixed dry-bulb and differential dry-bulb economizers. Both types require the HVAC system to be set to a minimum temperature and must be able to meet the setpoint for the discharge air.

Fixed dry-bulb economizers work by comparing outdoor air temperature to a preset temperature. Then, when this setpoint is reached, the system will bring in a minimum amount of outdoor air. The minimum amount of outdoor air will depend on the outdoor temperature and humidity ratio.

Dry-bulb economizers use a sensor to determine the difference between outdoor and return air temperatures. If the outdoor air temperature is lower, an actuator will open a damper to mix the outdoor air with the return air. This process will reduce the temperature in the home, but it may also result in high humidity.

Another type of dry-bulb economizer compares the interior dry-bulb temperature to the outdoor temperature. This information is used to regulate the amount of air that enters the building. The dry-bulb economizer is less expensive and less efficient than other types, but it doesn't provide adequate comfort.

Subcooling is a simple way to reduce the number of gas compressors in a refrigeration system. Mitsubishi Electric's design engineers figured it out more than 20 years ago, and they've been using it in VRF systems ever since. It works by merging two compressors into a single unit with two inputs, a main suction and an interstage side entrance that draws higher pressure gas.