Building Automation Room Control Example Buildings Are Often Broken Down Into Zones for Better Control of the HVAC System

p5:pg2 10/24/08 3:03 PM Page 1

Building Automation Room Control Example Buildings are often broken down into zones for better control of the HVAC system. These zones can have Variable Air Volume (VAV) systems with a VAV terminal unit or VAV “box”. A VAV box controls the air flow into the zone thereby controlling the environment of the zone.

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SUPPLY TO FROM UNIT ZONE

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AIR VOLUME CONTROL DUCT AIR FLOW The amount of air added to the zone is controlled by The amount of air flow to the zone is changed accord- opening and closing the air duct via a damper with a ing to the demand. An air velocity transmitter is used damper actuator. to monitor the duct air flow. • Product used: DD Damper Actuator. • Product used: MS Pressure Transmitter that has square root extraction for air velocity.

ROOM TEMPERATURE AND CARBON DIOXIDE The amount of air flow to a zone is varied based on occupancy in a zone. The occupancy is determined by the concentration of carbon dioxide in the zone. WATER FLOW CONTROL • Product used: CDW Carbon Dioide VAV systems can include heating coils of hot water and Temperature Transmitter that the air flows past. A zone valve is used to change the amount of hot water added to the heating coil. Zone systems can include radiant heating systems. A zone valve is used to change the amount of hot water added to the radiator in the zone. • Products used: ZV1 ROOM TEMPERATURE AND HUMIDITY Zone Valves. A wall mounted temperature and humidity transmitter is placed in the zone to monitor the zone conditions and determine demand. • Product used: RHT-W Humidity and Temperature Transmitter.

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