Variable Air Volume Distribution Units CII, September 1 st, Home

Variable Air Volume Distribution Units CII, September 1 st, 2010 1

VAV It s All About Measuring Airflow Accurate air flow measurement allows you to: Provide the absolute minimum air flow needed for ventilation. Use a larger sized box to reduce air pressure drop in the system. Ensure that the controller has an accurate signal, which gives your system the capability to feed only the needed CFM. The four A s of accurate air flow measurement:.. Accurate Airflow Traverse Amplified Velocity Pressure Averaged Pressure Output Abated Noise & Pressure Drop

Accurate Air Flow Traverse Look To ASHRAE 2001 Fundamentals Page 14.17 Measuring Flow in Ducts that s what we did to design our Flowstar Airflow Sensor Figure 6 - Measuring Points for Round Duct Traverse Log-linear Rule for Circular Ducts Provides specific measuring point locations for 6, 8, and 10 measuring point per diameter configurations

Accurate Air Flow Traverse

Amplified Velocity Pressure What is Velocity Pressure (P v )? THE CONTROLLER S DIFFERENTIAL PRESSURE SENSOR The controller s differential pressure sensor measures the difference between the TOTAL pressure (P t ) and the STATIC pressure (P s ).

Amplified Velocity Pressure Why amplify velocity pressure? Because all differential pressure sensors have a minimum differential pressure, below which they lose control. (typically 0.015 wg) Amplification allows the controller to react to lower air flows, since the differential pressure transducer still sees a measureable difference. Compare the differential pressure reading for the same airflow to a typical pitot sensor: CFM(Size 8) FPM Pv(Pitot) dp(flowstar) 1000 (max) 2865 0.56 w.g. 1.50 w.g. 800 (typ.) 2400 0.36 w.g. 0.99 w.g. 160 (20%) 480 0.015 w.g. 0.04 w.g.

Averaged Pressure Output Problems with the Non-Averaging Method The signal from the ports closest to the connectors are vastly overweighted. The tubes from the connector to the center point must be perfectly matched any difference in length will reduce accuracy.

FlowStar TM Airflow Sensor The four A s of accurate air flow measurement:.. Accurate Airflow Traverse Equal concentric measurement points per AHRAE Fundamentals Amplified Velocity Pressure P v amplified 230 to 290% Averaged Pressure Output Center averaging on all units Abated Noise & Pressure Drop

Abated Noise and Pressure Drop Scaled Drawing - Size 8 Inlet Collar

Abated Noise and Pressure Drop Lower Percentage of Free Area Causes: Higher Air Velocity More Pressure Drop More Noise

Factory Integrated Johnson Controls DDC Controls Scheduling VAV boxes and controls together: Provides a single source of responsibility for the successful operation of the VAV system no finger pointing! Boxes arrive with software installed, and are under control as soon as they are powered up. Allows the controls team to easily integrate the controller and it s application in the factory. With our VMA controllers, the balancer does not need to climb a ladder all readings can be taken at the zone sensor. VMA 1610 BACNET CONTROLLER

Going Further With Wireless When you specify wireless BACnet controllers using the Zigbee TM standard: Put the zone sensor anywhere you want as long as it can see any other device on the system, you are connected. Units delivered with factory integrated wireless can be operational as soon as power is connected. Reduced controls installation cost controls technicians do not need to reach the boxes. Boxes can be moved during construction or in the future without worrying about the cabling to the sensor

VAV Terminals Superior & Certified Performance FlowStar airflow sensor ARI 880 certified sound performance. ARI 410 certified coil performance ETL certified Electronic controls installed within a NEMA 1 enclosure Composite shaft to eliminate condensate formation in the control box. Unique design wraps the insulation edges without the need for metal Model TSS, Outlet View nosing. Self-lubricating bearings reduce friction and air leakage 3 speed motors with SCR for precise and safe control of low air flows. TVS Parallel Flow Variable Volume Fan Powered 100-4100 CFM TCS Series Flow Constant Volume Fan Powered 100-4800 CFM

Single Duct Terminal With Electric Heat Heater Elements Located UPSTREAM of Valve Proper airflow over elements regardless of damper position. Eliminates nuisance contactor cycling. Prolonged element life. Reduces temperature stratification. Allows lower minimum CFM setpoint. cetl listed as an assembly. Fully modulating heat with absolutely silent SSR controls. Single point power connection for ease of installation. (Heater Removed)

Single Duct Terminal Design Flexibility Air flows from 100 to 8,000 CFM Water coils up to 4 rows for cold climates and low water temperature applications. Steam coils Factory integrated controls for BACnet, N2, and LON Integral sound attenuators for very sound-sensitive applications. Access doors to allow easy coil cleaning. LEED-compliant packaging Global design the same units are available throughout the world. Model TSS

Fan Powered Terminals TCS Series Flow Constant Volume Fan Powered 100-4800 CFM TVS Parallel Flow Variable Volume Primary 100-4100 CFM Fan up to 2,400 CFM Design Flexibility everything available on the single duct PLUS: Small footprint, and only 14 tall to 1,000 CFM, and only 17 tall to 2,300 CFM. Available ECM TM motor for increased energy savings. Can operate at up to 0.8 external static pressure. Integral sound attenuators for very sound-sensitive applications. Second inlet and control for ducted outside air available. Silent relays for staged electric heat (modulated heat is always silent). Dual point power to support emergency applications available. Global design the same units are available throughout the world.