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Variable Air Volume Distribution Units

CII, September 1st, 2010

HomeVAV – 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

HomeAccurate 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

HomeAccurate Air Flow Traverse

HomeFlowStarTM Airflow Sensor

The four “A’s” of accurate air flow

measurement:. .

Accurate Airflow Traverse

Equal concentric measurement

points per AHRAE Fundamentals

Amplified Velocity Pressure

Averaged Pressure Output

Abated Noise & Pressure Drop

Does this look familiar?

HomeAmplified Velocity Pressure

What is Velocity Pressure (Pv)?

THE

CONTROLLER’S

DIFFERENTIAL

PRESSURE

SENSOR

The controller’s differential pressure sensor measures the difference between

the TOTAL pressure (Pt) and the STATIC pressure (Ps).

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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.

Amplified Velocity Pressure

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FlowStarTM Airflow Sensor

The four “A’s” of accurate air flow

measurement:. .

Accurate Airflow Traverse

Equal concentric measurement points per

AHRAE Fundamentals

Amplified Velocity Pressure

Pv amplified 230 to 290%

Averaged Pressure Output

Abated Noise & Pressure Drop

HomeAveraged 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.

HomeFlowStarTM Airflow Sensor

The four “A’s” of accurate air flow

measurement:. .

Accurate Airflow Traverse

Equal concentric measurement points per

AHRAE Fundamentals

Amplified Velocity Pressure

Pv amplified 230 to 290%

Averaged Pressure Output

Center averaging on all units

Abated Noise & Pressure Drop

HomeAbated Noise and Pressure Drop

Scaled Drawing - Size 8 Inlet Collar

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Lower Percentage of Free Area Causes:

Higher Air Velocity

More Pressure Drop

More Noise

Abated Noise and Pressure Drop

HomeFlowStarTM Airflow Sensor

The four “A’s” of accurate air flow

measurement:. .

Accurate Airflow Traverse

Equal concentric measurement points per

AHRAE Fundamentals

Amplified Velocity Pressure

Pv amplified 230 to 290%

Averaged Pressure Output

Center averaging on all units

Abated Noise & Pressure Drop

Precision-machined aircraft grade aluminum

tubes

HomeFlowStarTM Airflow Sensor

The four “A’s” of accurate air flow

measurement:. .

Accurate Airflow Traverse

Equal concentric measurement points per

AHRAE Fundamentals

Amplified Velocity Pressure

Pv amplified 230 to 290%

Averaged Pressure Output

Center averaging on all units

Abated Noise & Pressure Drop

Precision-machined aircraft grade aluminum

tubes

THE PREMIER AIR FLOW SENSOR

IN THE VAV INDUSTRY

HomeFactory Integrated Johnson Controls DDC Controls

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

Scheduling VAV boxes and controls together:

HomeGoing Further With Wireless

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

When you specify wireless BACnet controllers using the ZigbeeTM

standard:

HomeVAV 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

nosing.

Self-lubricating bearings reduce friction and air leakage

3 speed motors with SCR for precise and safe control of low air flows.

Model TSS, Outlet View

TCS Series Flow

Constant Volume

Fan Powered 100-4800 CFM

TVS Parallel Flow

Variable Volume

Fan Powered 100-4100 CFM

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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 Elements Located UPSTREAM of Valve

Single Duct Terminal With Electric Heat

(Heater

Removed)

HomeSingle 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

HomeFan Powered Terminals

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 ECMTM 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.

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