An upgrade route for constant-volume air-conditioning systems
Carrier’s 3V control system provides a means of upgrading existing constant-volume air-conditioning systems. This is a bypass damper with a 3V controller attached.
A control system to improve the efficiency of existing constant-volume air-conditioning systems has been introduced by Carrier. The 3V control system used by the latest variable-volume and variable-speed technology has been packaged as a stand-alone retrofit system for the refurbishment market. Carrier 3V is an open-protocol system, providing 2-way communication with other systems. Existing constant-volume systems represent a considerable investment in ductwork and other hardware, so upgrading holds many attractions. 3V will bring constantly monitored, measurable indoor air quality to an existing installation. Energy savings are derived from treating air when occupants need it rather than supplying a constant volume of air into a space all the time whether it is needed or not. It is said that this change will revalue otherwise declining building stock, something that is needed when the construction of new offices has reached another low. Using 3V, temperatures can be controlled to about 0.3 K in different zones within a single floor or an entire small building. Control has been taken from the ‘cooling machine’ to individual zones. This technology is easy to install. A zone controller communicates data such as occupancy, set points, over-ride demand and diagnostic information to the system co-ordinator installed on the cooling machine — which could be a packaged unit or an air-handling unit. To compensate for temperature fluctuation in each zone, the zone controller modulates its damper to regulate airflow into the zone. A bypass controller compensates for changes in static pressure in the supply air duct and responds by varying the amount of airflow into the return-air duct or ceiling plenum. Pre-programmed energy-efficient routines built into the controller offer occupied and unoccupied set points, night-time cooling and, with carbon-dioxide sensors added, demand-control ventilation. The System Pilot can serve as a wall-mounted sensor for space temperature. The occupant can use the System Pilot to change set points and make occupancy over-rides. A security system regulates access to features for authorised users. The network of communicating devices can be viewed using a standard web browser. With additional Carrier remote-access devices, changes can be made to comfort levels or other settings. The capability of the system can be extended using a Carrier universal controller. It is available as part of 3V and can be operated by the System Pilot to integrate control of lighting, fans, pumps, boilers and other HVAC equipment.