HVAC System Control > Unitary DDC Controller

Existing Conditions

The existing equipment is under pneumatic, electric, or manual control that is very basic and may not work well. With this type of control, equipment runs longer than necessary to cover all possible expected operating conditions. These controls are subject to tampering when they fail to perform well, and cannot be set up with the energy-saving strategies available with modern digital controls.

Retrofit Conditions

We suggest replacing existing controls with a “unitary” automation controller. This type of controller is a standalone unit with input and output capability and a small LCD display and keypad. It would be programmed at the time of installation according to energy-conserving strategies specified by the design engineer. The building operator would be able to use the keypad to change basic settings such as occupancy schedules and temperature setpoints. Generally these controllers are members of product families that can be networked together into facility-wide DDC (Direct Digital Control) systems. DDC systems can include many safety and convenience features such as full graphic terminal operation, remote access via phone line, dial out of alarms, security monitoring, and trending of energy and equipment data.

For the purpose of this study, we are recommending the most cost-effective approach, which is the installation of small local controllers intended to save energy. The decision to connect several units together into a single network can be deferred until clear operating benefits are identified.

Further Benefits