Variable Volume Variable Temperature Control System · ©August, 2002 Environmental Technologies, Inc. • ETVT-II Catalog 7 SCU-LT8: The System Control Unit features: Ł Two line

ENVIRO-TEC®

ETVT IIVariable Volume

Variable Temperature Control System

Stock ID: CAT-ETVTAugust, 2002

©2002 Environmental Technologies, Inc.Largo, Florida USA

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TABLE OF CONTENTS

2 ETVT-II Catalog • ©August, 2002 Environmental Technologies, Inc.

ETVT-II SYSTEM OVERVIEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

SYSTEM CONTROL UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

ZONE CONTROLLERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

BYPASS CONTROLLER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

SDR TERMINAL UNIT SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

SGX TERMINAL UNIT SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

WDDCMON MONITOR/SETUP SOFTWARE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

SYSTEM DESIGN GUIDELINES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

SAMPLE APPLICATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

ETVT-II SYSTEM GUIDE SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

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ETVT-II SYSTEM

3©August, 2002 Environmental Technologies, Inc. • ETVT-II Catalog

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ETVT-II SYSTEM OVERVIEW


Direct Digital Zone ControlThe Environmental Technologies Variable Temperature(ETVT-II) control system provides Direct Digital Control(DDC) of multi-zone heating and cooling systems. TheETVT-II system components are designed to provide theadvantages of intelligent, microprocessor-based comfortcontrol at a very reasonable cost.

The use of DDC controllers allows the entire system tocommunicate essential information between the controllersso that the system is able to make the most efficient useof the HVAC unit's heating and cooling capacity to achieveoptimum temperature control.

The ETVT-II system allows the building manager to eas-ily monitor the entire system and, if desired, modify itsoperation as building usage or requirements change.

Pressure Independent ControlThe ETVT-II zone terminal controllers feature pressureindependent operation, automatic changeover, and prop-ertional, integral, and derivative (PID) temperature control.

Fan Powered TerminalsIn addition to standare single duct terminal units, the ETVT-II system is suitable for use with Enviro-Tec's entire lineof fan powered, hydronic heat, and electric reheat termi-nal units. This provides a degree of flexibility that waspreviously only possible with expensive high-end DDC sys-tems.

Commercial/Industrial Duty EquipmentEven though the ETVT-II system is designed to be costeffective in low tonnage installations, it uses Enviro-Tec'shigh quality commercial grade pressure independent DDCcontrollers and terminal units for unsurpassed functional-ity and reliability.

All ETVT-II controllers, terminal units, and computer pro-grams are designed and manufactured by Enviro-Tec.This sole sourcing yields reliable, consistent operation andprovides fast solutions to potential HVAC system designproblems.

Small or Large Building UseA typical ETVT-II installation consists of a System ControlUnit (SCU), 1 to 64 VAV terminals, a pressure relief(bypass) terminal unit, and a static pressure (bypass) ter-minal controller. However, up to 99 SCU's can be linkedtogether for larger projects and monitored from a centralpersonal computer (PC).

Direct Expansion or Hydronic SystemsThe ETVT-II system is frequently applied with directexpansion rooftop and split systems which require main-taining a constant DX coil airflow. The ETVT-II pressurerelief (bypass) system maintains supply duct static pres-sure and coil CFM. This system consists of a standalonebypass terminal controller and one or more bypass termi-nal units.

Central HVAC Unit ControlThe System Control Unit (SCU) provides the HVAC unitcontrol portion of the system. It communicates with allof the zone terminal controllers in the system to determinethe building heating and/or cooling requirements. Basedon these requirements and its discharge temperature sen-sor, the SCU controls the HVAC unit by activating anddeactivating relays which control the HVAC unit fan withup to seven stages of heating and/or cooling.

Output relays are field definable, providing maximum flex-ibility and backup output devices for smaller systems.

Operator InterfaceThe System Control Unit (SCU) includes a Liquid CrystalDisplay / Keypad operator's panel which can be used toconfigure and monitor all zone controllers in the system.

The communications interface socket allows a Windows®

compatible computer to be connected to the system usinga factory supplied cable. A powerful, user friendly computer program allows configuration and monitoring ofthe SCU and all of the zone controllers in the system directly or remotely via an optional 2400 baud modem.

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ETVT-II SYSTEM DIAGRAM


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SYSTEM CONTROL UNIT (SCU)


The System Control Unit (SCU) monitors each zone temperature. Its control logic determines the central air con-ditioning unit mode status, either heating, cooling, or ven-tilation.

The SCU�s battery-backed real time clock / calendar withautomatic leap-year and daylight savings time adjust-ments schedules occupied (daytime) and unoccupied (nightsetback or setup) periods for each day of the week and aspecial holiday schedule.

An electronic duct temperature sensor measures the discharge air tem-perature from the HVAC unit. TheSCU meets zone load demands whileavoiding low suction temperaturesand coil frosting while in the coolingmodes with built in off-cycle timers.

The SCU protects a heat pump froma manual reset nuisance tripout on highpressure by sensing a high supply airtemperature condition and cycling offmechanical heating for a preset off-cycle period.

Configuration and monitoring of all ofthe controllers in the system is doneat the SCU. Up to 99 System ControlUnits can be connected together ontheir own communications network. With 64 terminals perSCU, one ETVT-II system could serve an installation withover 6,000 terminal units and 99 central air handling units.

A Windows® compatible PC on-site or connected bymodem allows an owner operator, system designer, installer,or service technician to set up all air terminals and systemoperating parameters including zone temperature setpointsand to perform system check-out and diagnostics.

Sequence of OperationsThe System Control Unit provides eight field definable out-put control relays to interface with the HVAC unit. Bysequencing these relays, the SCU will call for fan opera-tion, up to 7 stages of heating, or up to 7 stages of cooling, heat pump changeover, or any combination of 8outputs.

Once every minute, the SCU communicates with each ofthe zone controllers connected on its communications network to determine the total heating and/or coolingrequirements of the building. A zone vote weighting system determines optimum central heating or cooling oper-ation.

Configuration settings in the SCU control the minimumand maximum duration of the cycles to limit excessivecycling of the HVAC unit. A preset ventilation periodbetween heating and cooling changeover allows the

ductwork to be purged saving energyand protecting the HVAC unit.

The SCU determines the requiredmode of operation. It turns individualheating or cooling stages on or off tomaintain the appropriate discharge airtemperature. The turn-on and turn-offtemperatures for each individual stageof heating or cooling can be configuredseparately. A programmable anticyclefunction for each output ensures thatthe cooling compressor(s) will not beshort-cycled during normal operationor after a power failure.

The SCU schedules up to fourteenprogrammable occupied periods perweek (two per day) and 16 program-

mable holiday periods. When the system is in unoccupiedmode, a command is sent to all the VAV units on the net-work to revert to their unoccupied mode settings. If the SCUis in unoccupied mode and all units are within the programmed temperature limits, the HVAC unit will be shutdown.

In the occupied mode, when all zones are satisfied, the unitfan operates continuously to maintain ventilation and airmotion. All terminal units are set at minimum CFM operation. The nominal air motion creates greater comfortand improves dilution of stale air with outside air from thecentral HVAC unit.

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SCU FEATURES


SCU-LT8: The System Control Unit features:

� Two line by 16 character liquid crystal and 20-key operator's panel

� Communications interface cable� Monitor/access software� Transformer� Disconnect� Line block

� Heating and cooling manual override switches� Terminal strip for connection to AHU� Painted enclosure with hinged access door� Eight field definable relays for control of any

combination of fan, heating, cooling and changeover outputs

Component Designations

System Control UnitDimensional Data

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ZONE CONTROLLERS


The DDC zone controller is microprocessor based and intelligently performs proportional, integral, and derivative(PID) control of the terminal functions including heatingor cooling votes, damper operation, and optional fanand/or electric heat to provide optimum zone comfort.

The zone controller provides pressure independent VAVflow control and automatic changeover operation. Eachzone terminal unit includes a regular thermostat or aSmart-Stat� display thermostat. Both thermostats includea zone temperature sensor, communications interface connector, and an unoccupied mode override switch.

The standard thermostat includes a temperature setpointcontrol knob. The Smart-Stat� includes a 4-digit greenLED display, a 6-position keypad, and a locking cover. TheSmart-Stat� lets the occupant see:� Cooling setpoint� Heating setpoint� Duct temperature� Room temperature� Unit CFM

Pressure Independent OperationEach zone terminal controller contains Enviro-Tec's exclusive flow compensated differential pressure transducer. In a VAV system, the static pressure in the ductwill change whenever any zone controller opens or closes its damper. This flow transducer enables the zonecontroller to calculate how much air is being supplied tothe zone so that it can keep the airflow constant even whenthe static pressure in the duct is changing. This is calledpressure independent operation. Pressure independentmeans that each zone is not affected by every other zonein the system and prevents constant temperature swings andnoisy breathing of the system. In addition, the zone controller can accurately maintain minimum ventilation airflow levels to ensure adequate ventilation while maximizing energy efficiency.

Stand-Alone OperationAlthough much of the power of the ETVT-II system liesin the ability of the controllers to communicate their heating and cooling needs to the System Control Unit, thezone controllers are designed to provide stand-alone operation if required. Because of this capability, if one partof the system loses power or malfunctions, the rest of thesystem can still operate normally. Each zone controllerkeeps track of the last time it communicated with the SCU;if a controller hasn�t communicated within the previous 90seconds, it will automatically switch to its occupied (daytime) operation and continue to operate normally. Thezone controllers do not rely on the SCU to tell them whetherthe HVAC unit is currently supplying hot air or cold airsince each controller has its own electronic duct temperature sensor. This sensor allows the controller todetermine the temperature of the supply air, compare thattemperature with the zone temperature, and then decidewhether to use the supply air for heating or cooling.

PID Temperature Control In order to provide optimum temperature control, the zonecontrollers use a proportional, integral, and derivative (PID)control algorithm.

This means that the controller has the ability to intelligent-ly determine the exact amount of cooling or heatingrequired by the zone.

PID control is a common-sense approach to temperaturecontrol. The proportional factor means that more heatingor cooling is supplied as the zone temperature gets furtheraway from set-point. The integral factor adds time intothe equation, which means that if a zone has been too hotor too cold for a period of time, the heating or cooling isincreased or decreased until the proper level is achieved.The derivative factor means that the zone controller willcompensate for rapid temperature changes, such as a largegroup of people entering a previously unoccupied confer-ence room.

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ZONE CONTROLLERS


Smart-Stat™ Standard Thermostats

Configuration SettingsEach zone terminal controller has flexibility in terms ofapplication and operation. The configuration settings aremodified using the WDDCMON Monitor/Setup Software(see page 16) and are retained by the controllers non-volatile memory in the event of a power failure.

The zone terminal controller has programmable setpointsfor occupied and unoccupied control modes including heating and cooling maximum and minimum airflow.Vote weighting factors for heating and cooling permit certain controllers to be given a higher or lower prioritythan others in determining the operation of the HVAC unit.An override time setting is also provided which allows acontroller to request activation of the HVAC unit if theswitch at the controller�s thermostat is depressed. Actualoverride time is totaled and stored in each zone.

Units with reheat capability, including fan induction terminals, can be configured to operate independently basedon local demands for heat without requiring the HVAC unitto be in heat mode. During occupied operation, fan terminals can be configured to provide heat without requiring activation of the HVAC unit�s fan. Fan terminalmotors are rated for air temperature of 122°F. If using seriesfan terminals with a changeover central system, care mustbe taken to limit supply air temperature to 120°F.

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ZONE CONTROLLERS



SDV942R: Single duct terminal with digital electronic controller,electric actuator, inlet duct ternperature sensor, trans-former, sheet metal enclosure, and regular thermostat.Available box sizes are: 4", 5", 6", 8", 10", 12", 14",16", 19", and 22".

SDV942S:Same as SDV942R but with Smart-Stat� thermostatwith 4-digit LED display and keypad.

SDV945R:Same as SDV942R with additional outputs to supporteither 2-stages of electric heat, 2-position hot waterheat, or floating modulating hot water heat.

SDV945S: Same as SDV945R but with Smart-Stat� thermostatwith 4-digit LED display and keypad.

FVV945R: Variable volume (parallel) fan powered supply unitwith digital electronic controller, electric actuator, inletduct temperature probe, transformer, fan relay, sheetmetal enclosure, and regular thermostat.

FVV945S:Same as FVV945R but with Smart-Stat� thermostatwith 4-digit LED display and keypad.

FCV945R:Constant volume (series) fan powered supply unit withdigital electronic controller, electric actuator, inlet ducttemperature probe, transformer, fan relay, sheet metalenclosure, and regular thermostat.

FCV945S:Same as FCV945R but with Smart-Stat� thermostatwith 4-digit LED display and keypad.

QW25, QW50:Standard 25 and 50 foot plenum rated Quick-Wire�cables. Custom lengths are available.

QW25N, QW50N:Standard 25 and 50 foot non-plenum rated Quick-Wire� cables. Custom lengths are available.

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Bypass Controller and Terminal: Most ETVT-II systems are utilized with a low cost constant volumeHVAC unit which must deliver a constant volume ofair in order to maintain acceptable unit operation.Therefore, a pressure relief system consisting of abypass terminal controller and from one to threebypass terminal units are used to provide constant airflow to the central HVAC unit.

The bypass controller includes a static pressure transducer for monitoring and controlling the duct static pressure. The controller is completely standaloneso that it is not dependent upon any other controllersfor proper operation. The bypass terminal communicates with the System Control Unit so thatthe static pressure can be monitored.

Sequence of OperationsOne to three bypass terminal units are operated in parallel to maintain constant duct static pressure. Ifthe duct static pressure rises above the setpoint, thebypass dampers will modulate open to lower the pressure and maintain the

setpoint. If the duct static pressure drops below thesetpoint, the bypass dampers will modulate closed toincrease the pressure and maintain the setpoint.

BYPASS CONTROLLER



BTC-O1:Digital electronic static pressure controller with static pressure transducer, sheet metal enclosure, andstatic pressure probe. Each bypass system requires oneBTC-01.

BPV-O1:Single duct bypass terminal unit (SDR) with electricactuator, terminal strip, transformer, and controlenclosure. Available box sizes are: 4", 5", 6", 8", 10",12", 14", 16", 19", and 22". The transformer in theBPV-01 provides operating power to the BTC-01 and,if used, the BPV-02 bypass terminal unit or units. Eachbypass system requires a BPV-01.

BPV-02:Same as BPV-1 but does not include transformer. Foruse as an additional bypass damper in systems withmultiple bypass dampers. Each multiple bypass system requires one or two BPV-02s.

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SDR TERMINAL UNIT SPECIFICATIONS


Both the zone and the bypass terminal units use the Enviro-Tec SDR terminal units. These are available insizes ranging from 4" to 22" and feature durable construction, low leakage, and excellent acoustical charac-teristics. Inlet collars for all box sizes are round (except for sizes 19 and 22 which are rectangular). The SDRhas an insulated rectangular duct connection.

UNITSIZE W H L A J YX

22

19

161412108654

34"

30"

24"20"16"14"12"10"10"10"

17 1/2"

17 1/2"

17 1/2"17 1/2"

15"12 1/2"

10"10"10"10"

11"

11"

17"17"13"13"11"11"11"11"

8"

8"

6 1/2"6 1/2"6 1/2"6 1/2"6 1/2"6 1/2"10 1/2"10 1/2"

32 1/4" x15 7/8"

28 1/4" x13 7/8"

15 7/8"13 7/8"11 7/8"9 7/8"7 7/8"5 7/8"4 7/8"3 7/8"

16 1/4"32 3/4"

16 1/4"28 3/4"

16 1/4"22 3/4"16 1/4"18 3/4"13 3/4"14 3/4"11 1/4"12 3/4"8 3/4"10 3/4"8 3/4"8 3/4"8 3/4"8 3/4"8 3/4"8 3/4"

NOTE: Sizes 19 and 22 have rectangular inlets.

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SDR GENERAL SELECTION DATA


TERMINALSIZE CFM

Min.∆Ps DISCHARGE NOISE CRITERIA (NC) RADIATED NOISE CRITERIA (NC)

ModelSDR/

SDR-SA

0.5" ∆Ps 1.0" ∆Ps 3.0" ∆Ps 0.5" ∆Ps 1.0" ∆Ps 3.0" ∆Ps

ModelSDR

ModelSDR-SA

ModelSDR

ModelSDR-SA

ModelSDR

ModelSDR-SA

Model SDR & SDR-SA

Model SDR & SDR-SA

Model SDR & SDR-SA

4

100 .01 -- -- -- -- -- -- -- -- --150 .01 -- -- 20 -- 28 20 -- -- --200 .01 -- -- 24 -- 33 27 -- -- 24250 .01 22 -- 27 23 37 32 -- -- 28

5

100 .01 -- -- -- -- -- -- -- -- --200 .01 -- -- -- -- 25 -- -- -- --300 .01 -- -- 20 -- 28 22 -- -- 20350 .01 -- -- 20 -- 27 20 -- -- 23

6

200 .02 -- -- -- -- 23 -- -- -- --250 .03 -- -- -- -- 24 -- -- -- --300 .04 -- -- -- -- 25 20 -- -- 20350 .06 -- -- -- -- 24 -- -- -- 22450 .10 -- -- 20 -- 28 22 -- -- 25550 .14 -- -- 24 20 32 27 -- 23 29

8

300 .01 -- -- -- -- 25 -- -- -- --400 .02 -- -- -- -- 23 -- -- -- 21500 .03 -- -- -- -- 24 -- -- -- 24600 .04 -- -- -- -- 25 -- -- -- 25800 .08 -- -- -- -- 27 20 -- -- 271000 .12 -- -- 20 -- 28 23 -- 20 29

10

600 .01 -- -- -- -- 28 -- -- -- 27800 .03 -- -- -- -- 27 -- -- -- 271000 .04 -- -- -- -- 27 -- -- -- 271200 .06 -- -- -- -- 29 23 -- -- 281400 .08 -- -- -- -- 29 23 -- -- 281600 .11 -- -- 20 -- 29 24 -- 22 29

12

800 .01 -- -- -- -- 24 -- -- -- 281100 .03 -- -- -- -- 24 -- -- -- 291400 .04 -- -- -- -- 25 -- -- -- 301700 .06 -- -- -- -- 27 22 -- 20 312000 .09 -- -- -- -- 29 24 -- 21 322300 .12 -- -- -- -- 29 24 -- 22 33

14

1100 .01 -- -- -- -- 24 -- -- -- 251500 .03 -- -- -- -- 25 -- -- -- 271900 .04 -- -- -- -- 25 20 -- -- 282300 .07 -- -- -- -- 27 22 -- -- 292700 .09 -- -- -- -- 28 23 -- 20 303100 .12 -- -- -- -- 28 24 -- 23 32

16

1600 .02 -- -- -- -- -- -- -- -- 282100 .03 -- -- -- -- 23 -- -- -- 302600 .04 -- -- -- -- 28 23 -- -- 303100 .07 -- -- -- -- 28 23 -- -- 323600 .09 -- -- -- -- 29 25 -- 22 334100 .12 -- -- -- -- 32 28 -- 24 34

19

2500 .06 -- -- 20 -- 28 20 -- 25 343000 .09 -- -- 20 -- 29 23 20 27 353500 .13 -- -- 20 -- 29 24 23 28 374500 .21 -- -- 20 -- 32 27 23 31 385500 .32 -- -- 20 -- 33 29 27 34 426500 .44 20 -- 23 -- 35 32 30 36 43

22

4000 .06 -- -- 22 -- 30 25 -- 27 375000 .10 -- -- 23 20 32 27 20 29 396000 .14 -- -- 24 22 33 28 21 32 397000 .20 20 -- 24 22 33 29 24 32 408000 .25 22 -- 25 22 34 30 27 33 40

NOTES:• Minimum ∆Ps is the static pressure difference between the terminal inlet and discharge with the damper wide open.• Performance data obtained from tests conducted in accordance with ARI Standard 880.• NC values are based on assumptions outlined in ARI Standard 885.• Dash (--) indicates NC level less than 20.• Discharge NC values based upon:

- 5' lined duct (12" x 12") with 1" thick fiberglass insulation - 6' lined 8" flex duct at diffuser- Maximum 300 CFM per diffuser - 5000 ft3 space- 10 feet from source

• Radiated NC values based upon:- 3' deep ceiling cavity - 5/8" thick - 35 lb./ft3 mineral fiber ceiling tile- 5000 ft3 space - 10 feet from source

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SGX TERMINAL UNIT SPECIFICATIONS


As an option, the Enviro-Tec SGX terminal unit may be used when round inlet and discharge are specified.These are available in sizes ranging from 4" to 16" and feature durable construction, low leakage, and excel-lent acoustical charactertistics.

UNIT SIZE D

6 5 7/8"

8 7 7/8"

10 9 7/8"

12 11 7/8"

14 13 7/8"

16 15 7/8"

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SGX GENERAL SELECTION DATA


MIN ∆PsMIN ∆Ps

+ .75"MIN ∆Ps

+ 1.5"MIN ∆Ps

+ 3" MIN ∆PsMIN ∆Ps

+ .75"MIN ∆Ps

+ 1.5"MIN ∆Ps

+ 3"275 .13 26 34 41 49 22 27 33 38315 .18 28 35 42 50 22 28 33 38350 .22 30 36 44 51 23 29 34 39390 .26 31 37 45 52 24 30 35 39430 .33 32 38 45 53 26 30 35 39470 .39 34 39 46 54 28 32 36 40510 .46 35 40 47 55 30 33 36 41490 .13 30 35 41 49 20 25 29 35560 .17 30 36 42 49 21 25 29 35630 .21 30 37 44 50 22 25 30 36700 .26 31 38 45 51 23 26 31 37770 .32 33 39 46 52 23 28 32 37840 .38 36 40 47 53 23 29 33 38905 .45 38 41 48 54 23 30 35 39765 .13 31 35 42 49 20 23 29 35870 .17 33 36 43 50 20 24 29 35980 .21 34 38 44 51 20 25 30 361090 .26 35 39 45 52 20 26 31 371200 .32 36 40 45 52 22 27 32 371310 .38 37 41 46 53 24 28 33 381415 .44 38 42 47 54 26 29 34 391100 .13 29 34 40 47 20 24 30 361255 .17 31 35 42 50 21 25 32 371415 .21 32 36 44 53 22 26 33 371570 .26 34 38 46 56 24 27 34 381725 .31 35 39 47 56 25 28 34 391885 .38 36 40 48 56 28 30 35 402040 .44 37 41 49 57 29 32 36 411500 .13 32 38 43 49 25 25 31 371710 .17 34 39 44 50 26 27 33 381925 .21 35 40 45 51 27 29 35 402140 .26 36 41 47 52 28 31 37 412355 .31 38 42 47 53 28 32 37 422570 .38 40 43 48 54 29 34 38 442780 .44 41 45 49 55 30 35 39 451945 .12 29 34 41 54 20 31 40 482225 .16 31 36 43 54 23 32 40 492500 .20 33 37 45 55 25 33 41 502780 .26 34 39 47 55 27 34 42 503060 .31 35 40 48 56 30 35 43 523335 .37 36 42 49 58 33 36 43 533615 .43 38 43 50 59 36 38 44 54

RADIATED NOISE CRITERIA (NC)DISCHARGE NOISE CRITERIA (NC)Min. ∆∆PtCFMTERMINAL

SIZE

16

14

12

10

8

6

NOTES:• Minimum ∆Ps is the static pressure difference between the terminal inlet and discharge with the damper wide open.• Performance data obtained from tests conducted in accordance with ARI Standard 880.• NC values are based on assumptions outlined in ARI Standard 885.• Discharge NC values based upon:

- 5' lined duct (12" x 12") with 1" thick fiberglass insulation - 6' lined 8" flex duct at diffuser- Maximum 300 CFM per diffuser - 5000 ft3 space- 10 feet from source

• Radiated NC values based upon:- 3' deep ceiling cavity - 5/8" thick - 35 lb./ft3 mineral fiber ceiling tile- 5000 ft3 space - 10 feet from source

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WDDCMON MONITOR/SETUP SFTW.


Included with every ETVT-II system is the ETVT-IIMonitor/Setup computer software (WDDCMON),which allows access to the System Control Unit andall of the zone terminal controllers connected on thecommunications network. This program can be usedon almost any Windows® compatible computer with aserial communications port. The computer is connect-ed to the System Control Unit's operator's panel or anyzone thermostat using a supplied interface cable.

WDDCMON provides a viewport to the internaloperations of the ETVT-II controllers (System ControlUnit, Zone Terminal Controllers, and BypassControllers) and also allows the configuration settingsin the controllers to be modified as desired. Systemoperation and maintenance are greatly simplified bythe ability to monitor and configure the entire systemfrom one central location without interruption of sys-tem operation.

WDDCMON is designed to be very easy to use, andall of the program functions can be performed withstraightforward keyboard operations. In addition, allconfiguration settings are made in common engineer-ing units (such as CFM, °F, and minutes or seconds)instead of using binary numbers or some other con-troller specific format.

Pictured on the following pages are just a few of theWDDCMON program screens as they appear duringactual program operation. They give summary infor-mation about the controllers on the network, providespecific information about the System Control Unitoperation, allow the SCU occupied schedule to be set,and allow the zone Terminal Controller Configurationsto be modified.

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SYSTEM DESIGN GUIDELINES


Designing an ETVT-II system is a fairly straightfor-ward process. The paragraphs which follow providegeneral suggestions on ETVT-II system applicationand also outline the actual component selection andlayout procedure.

Handling Load DiversityThe ETVT-II system was designed to meet the spe-cific needs of small buildings requiring a simple, costeffective means to provide multiple zone comfort con-trol. It was not intended to be used on all applications;therefore, care must be taken when applying this sys-tem.

On buildings demanding simultaneous heating andcooling, the ETVT-II system should not be used withone single unitary heating / cooling unit unless sometype of local zone heating fan terminal or reheat isused. The system is intended for buildings or areaswith zones that have similar load profiles (i.e. at anytime during occupied periods, all of the zones are call-ing for either heating or cooling). Buildings thathave large internal core areas in conjunction with sub-stantial exterior glazing must be examined carefully.

The ability of the ETVT-II system to incorporate fanpowered and reheat terminal units greatly expands thecapability of the system to handle diverse loads. Thisis particularly true of buildings with a small numberof zones which require perimeter heating during cer-tain periods of the day while the rest of the zonesrequire cooling. The option for adding reheat at thezone terminal is best suited for accommodating a smallnumber of problem zones. Buildings which requirecontinuous heating on the perimeter zones and con-tinuous cooling on the interior zones during cold dayswould require reheat on all perimeter zones. An alter-native solution to this is to use multiple ETVT-II sys-tems and multiple heating / cooling units or to use amix of cooling only VAV units and fan powered ter-minals with reheat.

Bypass ConfigurationsWhen using a constant volume air handler with a vari-able volume control system, there must be a meansfor diverting air back from the supply duct to the returnduct as the zone terminals modulate closed. This isdone by means of BPV-01 and BPV-02 bypass termi-nals. As the system static pressure increases, thebypass opens to unload the fan, thereby maintainingconstant static pressure.

The bypass system can be configured to either dumpair from the supply to the return via a section of duct-work or by dumping supply air into the plenum whenthe application permits. Typically, one configurationis chosen over the other based primarily on physicalconstraints.

One concern when dumping air back to the plenumfor an open air return is to make sure that the air han-dling equipment includes the necessary options toavoid pressurization of the plenum. This can becomea problem if the roof top includes an economizer.When the unit starts to pull outside air for economiz-er cooling, more air is entering into the building thanis being exhausted and causes the return air plenumto pressurize. Without some means for exhausting thisexcess air, cold plenum air will seep back into the zonethrough return air openings and cause possible tem-perature control problems.

System Control Unit SelectionA System Control Unit is required for control of eachair handling unit.

System Control Unit PlacementSince the SCU contains the operator�s panel and serv-ice tool port, the SCU should be placed in a locationwhere it is relatively easy to access. At the same time,it is important to prevent unauthorized access to theoverride control switches. The SCU is typicallyplaced in a mechanical room or closet.

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SCU Discharge Sensor PlacementThe SCU�s discharge temperature sensor is installedin the discharge ductwork of the HVAC unit. This sen-sor permits the SCU to control the activation ordeactivation of heating and cooling stages thereby con-trolling the discharge air temperature. The sensorshould be placed where it will accurately sense the dis-charge air temperature from the HVAC unit, prefer-ably between the HVAC unit discharge and the firstbypass terminal.

Zone Terminal Unit SizingProper sizing of the zone terminal units is critical inany HVAC system installation. The acoustical per-formance and overall comfort level in the zonedepends on this selection. Once the CFM require-ments for each zone have been determined throughload analysis calculations, refer to the SDR GeneralSelection Table on page 13 or the SGX GeneralSelection Table on page 15. In these tables you willfind noise criteria and pressure drop data for all ter-minal sizes at different air volumes (CFM). Unitsshould be selected for the maximum CFM setpoint atthe mid-range to upper mid-range of the table to ensuremaximum operating efficiency. At the low end of thetable, the ability to closely control is reduced; and, atthe high end of the table, excessive noise and pres-sure drop may be experienced. Select units at themidrange of the General Selection Table for mostapplications.

Fan Terminal Unit SelectionFan terminal units should be selected from the Seriesor Parallel Fan Terminal catalogs. With centralchangeover systems where supply air temperatureexceeds 120°F in the heating mode, parallel fan ter-minals should be used in lieu of series fan terminals.

Inlet and Discharge OptionsAll zone terminal units include standard round inletsand rectangular slip and drive discharge.

Communications Connection OptionAll zone terminal controller thermostats include a portwhich allows a Windows® compatible computer to beconnected directly to the zone thermostat through anETINT1 portable service tool interface.

Zone Terminal Unit PlacementPlacement of the zone terminal units will be dictatedprimarily by building layout constraints. It is impor-tant, however, to have a straight duct run into eachzone terminal unit that is at least as long as 1.5 equiv-alent duct diameters. This should be done to preventexcessively turbulent airflow conditions at the airflowsensor which can cause inaccurate airflow readings.

Zone Terminal PlacementAs with any thermostat, the ETVT-II zone thermostatsshould be located where they will best reflect the tem-perature of air which is being experienced by the

Zone Controller Airflow Ranges

UNIT SIZE

PRESSURE INDEPENDENT

ETVT-II Series Digital Electronics

Min.1 Max.2

4 35 225

5 55 350

6 65 550

8 120 1000

10 195 1600

12 280 2300

14 400 3100

16 550 4100

19 1025 6500

22 1450 8000

NOTES:1. Factory CFM settings (except zero) will not be made below

this range due to reduction in control accuracy.2. Above ranges are maximum ratings. For ideal selections,

do not size unit at maximum listed volumes.

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zone�s occupants. Typical guidelines for thermostatplacement should be followed, such as avoiding plac-ing the thermostat where a diffuser will be blowingair directly on it or where it will receive direct solarexposure. In addition, internal heat sources such ascopiers, computers, coffee makers, and refrigeratorsshould be avoided.

Bypass Terminal Unit SizingWhen sizing a bypass terminal, the unit should beselected to handle approximately 80% of the nomi-nal CFM for the air handler, minus the total of the min-imum CFMs for all of the zones (including anyconstant volume zones). For most applications thiswould typically be about 325 CFM per ton minus 10-20% of the total zone CFM requirements. See page24 for an example of bypass terminal sizing.

Once the CFM requirements have been determined forthe bypass terminal, refer to the SDR GeneralSelection table on page 13. The bypass terminalshould be selected at the upper mid-range of the per-formance tables to ensure that adequate pressuredrop is maintained across the terminal unit during100% bypass. It is very important that the bypass ter-minal is not oversized since this greatly affects therange of control. Also, never select units at the high-est end of the General Selection table. If the totalbypass CFM requirement is less than 6000 CFM,select an appropriate BPV-01 bypass terminal unit. Ifthe total CFM requirement exceeds 6000 CFM, usea BPV-01 bypass terminal unit and one or more BPV-02 terminal units, all of equal size.

Bypass System SelectionSelect a BTC-01 bypass terminal controller and theappropriate bypass terminal unit(s) (see page 11). Forsystems utilizing a variable volume roof top unit, abypass system is not required.

Bypass Terminal Unit PlacementThe bypass terminal unit should always be installeddirectly off the supply main, before any branch take-offs, and should be located in the immediate vicinityof the return air opening of the HVAC unit.

Bypass Terminal Controller PlacementThe BTC-01 bypass terminal controller contains thestatic pressure transducer and is connected by a shortpiece of plenum-rated tubing to the static pressureprobe. The static pressure probe is typically locateddown approximately 2/3 of the longest duct run awayfrom takeoffs. Connections are made from the bypassterminal controller to the bypass terminal unit(s) andalso back to the SCU.

Communications Cable RoutingFor proper communications it is very important thatthe communications cable is started at the SystemControl Unit and then connected from controller tocontroller in a single daisy chain fashion. Loops, tees,or splits in the cable may cause intermittent or totalcommunications failure. Refer to the ETVT-IIInstallation and Startup Manual for detailed informa-tion.

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SAMPLE APPLICATION


The building diagrammed on page 25 is typical ofmany real-world applications of the ETVT-II system.Although it is a relatively small building it has a widerange of heating and cooling requirements.

In this example, the rooftop unit is a 15 ton 2-stageunit with a nominal 6000 CFM capacity. For thisexample each zone�s minimum CFM will be assumedto be equal to 20% of the zone�s maximum CFM.

Load Diversity CheckWith the exception of Zones 3 and 5, this buildingwould be assumed to have a very uniform load pro-file. Since Zone 3 is an entrance foyer to the build-ing, the doors in that zone would probably be openedfrequently which would cause the load to fluctuate.There is also considerable glazing on the north wallof the entrance foyer area which adds to the problem.For Zone 3 it is recommended that some means ofre-heat be used to maintain space comfort. Using theSDV945 zone controller and baseboard reheat or ter-minal unit reheat will help compensate for zones suchas this in order to maintain overall building comfort.

The other possible problem zone is Zone 5. This isan executive office having glazing on the North andEast exposures. In the early evening, this zone couldrequire heating on certain days while the rest of thebuilding required cooling. Again, an SDV945 zonecontroller is recommended for this zone in conjunc-tion with some type of electric reheat.

Since the load profiles for the rest of the zones wouldremain fairly uniform throughout the day, they can becontrolled using standard SDV942 zone controllers.

System Control Unit SelectionSince the rooftop unit is a 2-stage heating / coolingunit, an SCU-LT8 would be selected for the SystemControl Unit. The SCU-LT8 includes a total of 8 relaysfor control of the fan, 2 heating stages, and 2 coolingstages with 3 relays remaining open for future use.

Zone Terminal SelectionZone terminal unit selections are made using the SDRSpecifications Table on page 13 or the SGXSpecifications on page 15. Based on the zone CFMsindicated on the building diagram, the table belowshows typical zone terminal unit selections.

Bypass Terminal SelectionAs is typical in most installations of this type, therooftop unit in this example is assumed to be a con-stant volume unit. Therefore, it requires one or morebypass terminal units and a bypass terminal controller.The total bypass CFM is calculated as shown below.

Total Bypass CFM= (Rooftop Unit CFM) x 80%

- (Variable Volume Zone CFM x 20%- (Constant Volume Zone CFM)

Therefore:= (6000 CFM) x 0.80

- (5175 CFM x 0.20- (500 CFM)

= 3265 CFM

ZONE CFM SIZE1 500 8"2 500 8"3 1000 10"4 500 8"5 600 8"6 375 6"7 500 8"8 500 8"9 350 6"10 350 6"

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SAMPLE APPLICATION


The total variable volume zone CFM is the sum of themaximum CFMs for zones 1 through 10. The totalconstant volume zone CFM is the sum of the CFMsfor the constant volume zones (the two bathrooms andthe file storage room).

The maximum volume that can be handled by a sin-gle bypass terminal unit is 6000 CFM. Therefore, inthis example one bypass terminal unit is required thatis capable of bypassing 3265 CFM. Referring to theSDR General Selection table on page 13, the idealselection would be to use one Size 16 terminal. A BPV-01 would be used for the bypass terminal.

System Components SummaryIn addition to the rooftop unit, the 13 components list-ed below provide a complete ETVT-II system for thebuilding in this example:

System Control Components:1 SCU-LT8

Zone Control Components:3 SDV942 - Size 65 SDV942 - Size 81 SDV945 - Size 81 SDV945 - Size 10

Bypass Control Components:1 BTC-011 BPV-01 - Size 16.

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GUIDE SPECIFICATION


A system of VAV terminal box controllers and a SystemControl Unit shall be supplied under this contract. All zonecontrollers shall be furnished and mounted by the select-ed VAV box manufacturer as an integral portion of the airterminal, along with the System Control Unit (SCU), whichis field installed. The control system shall be theEnvironmental Technologies ETVT-II system as specifiedbelow. The zone controllers shall be direct digital, pres-sure independent, with outputs for control of the unitdamper actuator, optional heat, and optional induction fan.

HARDWAREFor control of the HVAC unit, provide a System ControlUnit (SCU), consisting of a microprocessor based con-troller, an AHU discharge temperature sensor, all enclo-sures, and application software. The system controller shallbe ETL listed as an assembly.

For each VAV box, provide a VAV zone controller consist-ing of a microprocessor based controller, actuator, flowcompensated differential pressure transducer, enclosure, andapplication software.

Provide, if required, at least one pressure relief terminal(bypass terminal) with an electronic static pressure con-troller, electric actuator, and pressure transducer.

All electric actuators must incorporate a current limited DCmotor. Actuators incorporating AC synchronous motorsare not acceptable.

Casing shall be constructed of 22 gauge zinc-coated steel,mechanically assembled and sealed to form an air-tight con-struction with maximum casing air leakage of two (2) per-cent at 3" W.G. Spot-welded casings are not acceptable.

Insulation shall line the interior casing walls and shall notbe less than 1/2" thick dual density fiberglass with 4 p.c.f.skin outer layer. The material must comply with UL181and NFPA 90-A with no raw edges exposed to the airstream.All insulation shall be adhered to the unit casing by twomeans: i.e. an NFPA 90-A approved adhesive and amechanical fastener welded to the unit casing wall. Unitsutilizing approved adhesive only are not acceptable. Rawinsulation edges on the discharge of the unit must be cov-ered with metal liner to eliminate flaking of insulation dur-ing field duct connections.

Valve Assembly shall be manufactured of a 22 gauge airvalve body to handle high pressure and a 16 gauge com-

posite damper blade with key attached to a solid shaft. Theshaft shall have a position indicator marked on the end forverification of damper position. Two galvanized damperblades shall sandwich closed cell foam gasket material, pro-viding for minimum valve leakage. Damper leakage shallnot exceed two (2) percent of unit's maximum ratedcapacity with inlet pressure up to 6" W.G. Damper shallpivot in Delrin® self lubricating bearings that are unaffect-ed by temperature and humidity. The valve assembly shallhave built-in maximum and minimum heavy gaugemechanical stops to prevent over-stroking of the damper.

Airflow Sensor must be equipped with a center averag-ing chamber and have multi-axis sampling tubes. The sen-sor shall be designed to provide a differential pressure signalwhich is amplified at least 2.5 times the normal velocitypressure, over the full capacity range of the terminal.Pressure measuring taps shall be provided external to theunit with an airflow curve for ease of air balancing.

All the above components shall be original equipment man-ufactured and furnished by the VAV unit manufacturer. A24 VAC (output) transformer shall be mounted at the SCU,bypass damper, and each zone controller to match the powerrequirements of the building.

CONTROLThe System Control Unit (SCU) shall poll all zone con-trollers at least once every sixty seconds to determine theoptimum mode of operation for the HVAC unit. This opti-mization shall be configurable through supplies softwareor operator panel to ensure optimum system operation inthe building. It shall determine the current HVAC unit'sheating or cooling status, by a zone weighting factor uniqueto each unit, to allow optimum system control. For oper-ation in the event of communications failure, the SCU shallbe equipped with manual indicating override switches topermit continued fan, cooling, or heating operation. Also,the SCU shall be equipped with one mechanical fan/cool-ing override switch and one mechanical fan/heating over-ride switch for temporary system operation in the event ofSCU failure.

The SCU shall contain a battery-backed internal time clockfor determining system scheduling of occupied periods.The time clock shall be quartz crystal locked and shall havean accuracy better than +/- 0.0023% @ 77°F. An option-al external time clock or contact closure shall be able tooverride the system schedule.

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GUIDE SPECIFICATION


Each VAV unit shall be capable of complete stand-alonepressure independent operation and shall not depend oninformation from any other element in the building (includ-ing the SCU or other VAV terminals) for effective roomtemperature control. Failure of any component in the unitshall not cause the interruption of control by any other VAVcontroller. The zone controllers shall have multiple con-trol modes, each with unique temperature and flow set-points, for optimum autonomous operation. Each VAV unitshall control zone temperature using a proportional, inte-gral, and derivative (PID) control algorithm.

SETPOINT STORAGEAll control setpoints shall be maintained in non-volatilememory (EEPROM) to enable unit reset after a power fail-ure. All setpoint variables shall be established through thesystem control unit operator's panel or through the com-munications network using a standard Windows® compat-ible personal computer or laptop computer. Cable andsoftware shall be supplied by the manufacturer.

ROOM TEMPERATURE SENSORSThe zone controller's room temperature sensors with anintegral temperature setpoint adjustment shall be provid-ed by the VAV terminal manufacturer. Room temperaturesensor enclosures shall be of high-impact plastic and beequipped with a communication connection at the zone con-troller. The temperature sensor enclosure shall have anoptional tamper-resistant cover. The desired room temper-ature set at the room sensor shall be limited in range byprogrammed limits at the controller. Sensors shall havean accuracy of +/- 0.4°F @ 70°F. All units shall have anight set-back override switch to enable a temporary sys-tem reset to daytime operation.

FLOW MEASUREMENTAll zone controllers shall be equipped with a multi-axiscenter averaging flow sensor in the unit inlet, which shallbe connected to a flow compensated pressure transducermounted on the controller. The flow measurement shallbe independent of space (plenum) temperature within therange of 30°F to 150°F or supply air temperature from 50°Fto 110°F to within +/- 5% of rated flow. Minimum reso-lution of the flow signal shall be to within 15 FPM from400 FPM to 3000 FPM. The measured flow shall be main-tained within set maximum and minimum limits regard-less of inlet pressure.

DUCT TEMPERATURE SENSORThe System Control Unit shall have a duct temperature sen-

sor for use in monitor and control of the HVAC unit's dis-charge air temperature. Each zone controller shall have asupply inlet duct temperature sensor for determiningchange-over operation. Duct temperature sensors shall beinterchangeable +/- 1°F at 70°F.

REHEAT OPTIONSZone controllers shall optionally have the capability of con-trolling either a tri-state hot water valve or up to two stepsof electric heat. The heater and controller shall be listedby ETL or UL as an approved assembly and shall be pro-vided by the terminal unit manufacturer. The zone con-trollers shall optionally be capable of controlling aninduction fan for constant volume (series flow) orsequenced induction (parallel flow) operation, if desired.All units including the controller shall be listed by ETLas an assembly.

CONNECTIONSConnections between controllers and wall mounted sen-sors shall be made by factory provided Quick-WireTMcables. Communications between units shall be made with20-22 AWG twisted/shielded pair with drain, plenumapproved cable.

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Documents

Variable Volume Variable Temperature Control System · ©August, 2002 Environmental Technologies, Inc. • ETVT-II Catalog 7 SCU-LT8: The System Control Unit features: Ł Two line