DDC Integration – HVAC DDC ControlsDDC Integration | HVAC DDC Controls - This is an electrical project which is in the process of a changing of the old control system to a new DDC control system. Installing new controls in an occupied building takes plenty of planning to avoid interruption in air conditioning or heating. The old control system was a basic electro-mechanical control system which little more than just basic building management control.

DDC Integration | HVAC DDC Controls - VVT System

The old system is shown on the left while the new DDC control system is shown on the right. The new DDC Control system offered modern state of the art air conditioning and heating DDC control and the ability for building management and maintenance to monitor the system remotely over the internet. The remote monitoring and control give a building manager a distinct advantage in the monitoring and remote control of the buildings HVAC and lighting systems.

This building had 40 Variable Volume Terminal (VVT) zones with 40 rooftop air conditioning and heating units. This VVT system required static pressure control to control bypass dampers to relieve excess static pressure when the VVT dampers close. The DDC system reads static pressure from a static pressure transducer. VVT systems read CFM’s or air flow measured in Cubic Feet per Minute passing through the duct for the VVT zone. When the system requires heating CFM’s are low and when the system is calling for air conditioning the CFM’s are high. The air handlers in this system were constant volume.

DDC Integration | HVAC DDC Controls - Constant Volume

Integrating DDC with a constant volume system is fairly basic and really depends on what the owner wants for control. There are many manufacturers of HVAC equipment and they have their very own sequence of operation for control purposes especially unitary rooftop units under 20 tons. In that regard, the DDC integration is simple with some temperature sensors and a relay to enable the unit to begin its sequence. DDC would also be integrated into the smoke alarm system in the event of smoke detection in the ductwork.

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DDC Integration | HVAC DDC Controls

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