installation instructions...in the hvac unit 036-33035-001-a-1101. 036-33035-001-a-1101 2...

CONTENTS

TIPS BEFORE BEGINNING INSTALLATION . . . . . . . . . 2

ZONE MANAGER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

ZONE MANAGER ADDRESSING . . . . . . . . . . . . . . . . . . 5

COMMUNICATIONS LOOPS . . . . . . . . . . . . . . . . . . . . . 6

COMMUNICATIONS LOOP WIRING OVERVIEW . . . . . 6

BYPASS DAMPER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

ZONE DAMPERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

MOUNTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

ZONE CONTROLLERS . . . . . . . . . . . . . . . . . . . . . . . . . 10

CONSTANT VOLUME CONTROLLERS . . . . . . . . . . . . 13

CONSTANT VOLUME CONTROLLERADDRESSING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

ZONE SENSORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

SUPPLY AIR TEMPERATURE SENSOR . . . . . . . . . . . 17

RETURN AIR TEMPERATURE SENSOR . . . . . . . . . . . 17

OUTSIDE AIR TEMPERATURE SENSOR . . . . . . . . . . 17

STATIC PRESSURE SENSOR . . . . . . . . . . . . . . . . . . . 17

AUXILIARY RELAY BOARD FOR ZONECONTROLLERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

ZONE CONTROLLER RELAY EXPANSIONBOARD OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . 18

COMMLINK II INTERFACE . . . . . . . . . . . . . . . . . . . . . . 18

APPENDIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

INSTALLATIONINSTRUCTIONS

MERIDIAN PLUS

MERIDIAN PLUSSYSTEMMANAGER

TO OTHERMeridian Plus

ZONE MANAGERS

Meridian PlusZONE MANAGERTYPICALLY MOUNTED

IN THE HVAC UNIT

036-33035-001-A-1101

036-33035-001-A-1101

2 Installation Instruction - Meridian Plus

TIPS BEFORE BEGINNING INSTALLATION

Take a few moments to review the following before beginninginstallation of the Meridian Plus System.

• Familiarize yourself with all system components andreview all documentation. Pay special attention to “Cau-tions” and “Warnings” since these may keep you fromexperiencing unnecessary problems.

• Before installing zone dampers, be sure to tag eachdamper with its appropriate location. A set of labels isincluded with this manual. It is also best to set the zonecontroller address switches before mounting in drop ceil-ings. Use the Zone Address Worksheet to list all zonelocations. This will assist you greatly when setting up thesystem.

• Be sure and install all wiring according to local, state,and national codes.

• Pay close attention to communication wiring since themost common mistakes are made in this area. Polarity isthe most important rule. Make notes on your wiring dia-grams as to which color wire you will be using on eachterminal.

• When in doubt - ask! Contact your local Meridian distrib-utor if you have any questions. The only dumb questionsare the ones you don’t ask.

• Remember - each electronic device contains only onepuff of smoke. If you release it, you have voided the war-ranty! So please be careful and pay attention

FIGURE 1: SYSTEM OVERVIEW

NOTEMeridian Plus systems use two separate types ofcommunications loops. The Network Loop connectsonly to the Zone Managers and the CommLink II.The Local Loops connect between the Zone Man-ager and the Zone Controllers for that HVAC unit.Each Zone Manager has its own Local Loop for con-nection to associated Zone Controllers and anyadditional Constant Volume units and the SystemManager.

Do not connect zone controllers, constant vol-ume units or the system manager to the networkloop!

Meridian PlusZONE MANAGERTYPICALLY MOUNTED

TO OTHERMeridian Plus

ZONE MANAGERS

MERIDIANPLUSSYSTEMMANAGER

036-33035-001-A-1101

Installation Instruction - Meridian Plus 3

ZONE MANAGER

The Zone Manager may be installed in any convenient pro-tected location. Observe the recommended environmentallimitations for the Zone Manager (see Technical Data sectionof the product data sheet) when choosing a location.

The Zone Manager may be mounted without removing thecontroller from the mounting plate. The unit is mounted byfour (4) screws in the corners. Select the correct screws orother fasteners for the type of mounting material being uti-lized.

FIGURE 2: MERIDIAN PLUS ZONE MANAGER

036-33035-001-A-1101


FIGURE 3: ZONE MANAGER WIRING

MERIDIAN PLUSZONE MANAGER

Use extreme care not to damage any of the elec-tronic components while mounting the backplate.Mark the holes then remove the Zone Managerbefore drilling. Do not allow metal shavings to fallonto the circuit boards.

036-33035-001-A-1101


The Zone Manager requires the following electrical connections:

18 Gauge minimum unless otherwise noted.

ZONE MANAGER ADDRESSING

FIGURE 4: ZONE MANAGER ADDRESS SWITCH SETTING

-24 VAC Supply Voltage 2 Conductors

-Communications Loops 2 Conductor twisted pair with shield(Belden #82760 or equivalent)

-Supply Air Temperature Sensor (24 ga. Min.) 2 Conductors

-Return Air Temperature Sensor (24 ga. Min.) 2 Conductors

-Outside Air Temperature Sensor (24 ga. Min.) 2 Conductors

-Supply Static Pressure Sensor (24 ga. Min.) 3 Conductors

-Bypass Damper 4 Conductors

-HVAC Unit Control Wiring R-Common G-FanY1-Cool 1 Y2-Cool 2

W1-Heat 1 W2-Heat 2

-Additional wires depending on stages Y3 through Y6 (optional board required)W3 through W6 (optional board required)

TIPAfter making all electrical connections it is advised to unplug all terminal blocks on the ZoneManager until you are ready to begin the checkout procedure. This may help to prevent dam-age if wiring errors occur elsewhere in the system during installation or start-up.

036-33035-001-A-1101


COMMUNICATIONS LOOPS

Both the Network Loop and the Local Loops are two wireshielded RS-485. The loops are best connected in daisychain configuration, meaning the loops are connected fromone controller to another. It is not necessary to sequentiallyaddress the zone controllers in relation to their location on theloop. Cable must be Belden No. 82760 or equivalent.

COMMUNICATIONS LOOP WIRING OVERVIEW

The daisy chain is the best method for running a communica-tions loop since there is only one starting point and one end-ing point for each of the communications loops. (Figure 5).

Even though the daisy chain configuration is preferred, thestar configuration can also be used. If required, a combina-tion of the two can also be used. Remember, the best commloop wiring is the one which utilizes the minimum number ofends while using the shortest wiring path.

.

TIPIncorrect wiring of the communications loop is themost common mistake made during installation.Before beginning installation, write down the wirecolor used on each terminal connection and consis-tently maintain that color code. It is recommendedthat a continuous wire run be made betweendevices. Anytime a splice is made in the cable youincrease your chance of problems.

Make sure when you are inserting wires into the ter-minal blocks that strands of wire do not stick out andtouch the next terminal. This could cause a short orerratic operation.

NOTEMeridian Plus systems use two separate types ofcommunications loops. The Network Loop connectsonly to the Zone Managers and the CommLink II.The Local Loops connect between the Zone Man-ager and the Zone Controllers for that HVAC unit.Each Zone Manager has its own Local Loop for con-nection to associated Zone Controllers and anyadditional Constant Volume units and the SystemManager.

Do not connect zone controllers, constant vol-ume units or the system manager to the networkloop!

NOTEThe loop does not have to follow the controlleraddress sequence.

If comm loop is not installed in conduit be careful toposition the cable away from high noise devices likefluorescent lights, transformers, VFD’s, etc. Conduitis not required for comm loop wiring unless requiredby local codes.

036-33035-001-A-1101


FIGURE 5: COMMUNICATION LOOP WIRING, DAISY-CHAIN CONFIGURATION

Even though the daisy chain configuration is preferred, thestar configuration can also be used. If required, a combina-tion of the two can also be used. Remember, the best commloop wiring is the one which utilizes the minimum number ofends while using the shortest wiring path.

NOTEThe loop does not have to follow the controlleraddress sequence.

If comm loop is not installed in conduit be careful toposition the cable away from high noise devices likefluorescent lights, transformers, VFD's, etc. Conduitis not required for comm loop wiring unless requiredby local codes.

036-33035-001-A-1101


BYPASS DAMPER

The bypass damper is mounted similar to the zone damp-ers, in fact the only difference in most cases is the size. Thebypass damper should typically be sized for at least 60-70percent of the total design CFM. More than one bypassdamper may be slaved together when it is not practical touse a single large damper. As with the zone dampers it isoften easier to mount the actuators before installing thebypass damper in the ceiling.

See Figure 7 for damper actuator mounting instructions.

The bypass damper should be installed as close as possibleto the rooftop unit.

FIGURE 6: BYPASS ACTUATOR WIRING

If sheet metal screws are used to mount the damp-ers, be certain that they do not interfere with themovement of the damper blade.

Never depress the actuator clutch with powerapplied. Unplug the actuator cable before depress-ing the clutch and attempting to rotate the damperblade.

If the fan system has the capability of producingstatic pressures which could damage ductwork youmust provide a manual reset, high pressure limitswitch to cut-off the fan system in the event of highduct static. Do not use your Meridian System as asafety device

036-33035-001-A-1101


ZONE DAMPERS

Generally, zone dampers come preassembled with the actu-ator and Zone Controller. If not, the following instructions willassist you.

MOUNTING

In most cases it is preferable to mount the damper actuator tothe zone damper prior to mounting the damper in the ceiling.Before installing the zone damper, check for free movementof the damper blade by depressing the clutch on the damperactuator and moving the blade between it’s full open and fullclosed positions. Any binding or incorrect adjustment shouldbe corrected before mounting the damper.

Zone dampers should be securely hung using either wire cra-dles or metal strapping. While the dampers may be hung inany position, avoid sharp kinks in flexible duct to prevent air-flow restrictions. If an air flow sensor is mounted, always besure that the tips of the sensor are pointing down. The zonedampers should be insulated when installed in non-condi-tioned spaces to avoid sweating and to improve energy effi-ciency.

FIGURE 7: TYPICAL ACTUATOR MOUNTING

NOTEDirect acting actuators drive clockwise to open.Reverse acting actuators drive counter clockwise toopen.

Never depress the actuator clutch with powerapplied. Unplug the actuator cable before depress-ing the clutch and attempting to rotate the damperblade. Do not force the damper blade as this candamage the gears in the damper actuator.

If sheet metal screws are used to mount the damp-ers, be certain that they do not interfere with themovement of the damper blade.

036-33035-001-A-1101


ZONE CONTROLLERS

Generally, Zone Controllers are supplied mounted on thezone dampers. The Zone Controllers are mounted in snap-track which is typically located on the zone dampers. Orientthe board in the snap-track so that the actuator, flow sensor(optional), and auxiliary relay board (optional) cables willreach their respective connectors on the Zone Controller, ifthey are used. Press the board into the snap-track carefully toavoid damaging any of the electronic components on the cir-cuit board. To remove a board from the snap-track, carefullypull one edge of the snap-track away from the board withyour fingers and remove the board.

Consider serviceability of the location when mounting theZone Controllers. They should be easily accessible to facili-tate servicing.

Do not use any tools to pry the board loose. This willdamage the board and/or the snap-track.

When mounting the snap-track be sure the heads ofthe screws do not protrude far enough to touch thebottom of the Zone Controller circuit board.

TIP

Use small stickers on the ceiling grid or tiles to helpfuture service personnel locate system components.If you use small stickers from an office supply store,you can get different colors to code the location ofvarious components.

TIP

After making all electrical connections it is sug-gested that all terminal blocks on the Zone Control-ler be unplugged until you are ready to begin thecheckout procedure. This may help prevent damageif wiring errors occur elsewhere in the system duringinstallation or start-up. This is particularly importantwith the Zone Controllers since an error on one unitmay prevent any of the others from working until theproblem is found and corrected.

Polarity is very important when connecting power tothe controllers! The grounded side of the controltransformer must be connected to the terminallabeled GND on the Zone Controller. If a singletransformer is used to power more than one ZoneController you must connect GND-to-GND and24VAC-to-24VAC on each zone controller. Failureto observe polarity will result in damage to oneor more components in your system.

The Zone Controller requires the following electrical connections:

24VAC Supply Voltage 2 Conductors

Communications Loop 2 Conductor twisted pair with shield(Belden #82760 or equivalent)

Room Temperature Sensor 2 Conductors for standard sensors3 Conductors for sensors with setpoint adjustment

Fan Terminal units / Auxiliary Heat 2-4 Conductors see wiring diagrams for(Optional) Aux. Relay board

036-33035-001-A-1101


FIGURE 8: ZONE CONTROLLER WIRING

036-33035-001-A-1101


Set the Zone Controller Address Switch following thesupplied addressing instructions.

FIGURE 9: ZONE CONTROLLER ADDRESS SWITCH SETTINGS

Incorrect addressing is the number one cause ofcommunication problems. Check the addressingcarefully. Remember, the Zone Controller only readsthe switch during a power-up. If the address switchis changed, the unit must be turned OFF then ONbefore the new setting will be recognized.

NOTEIgnore any markings or numbers on the switch. Usethis chart!

036-33035-001-A-1101


CONSTANT VOLUME CONTROLLERS

The Constant Volume Controller may be installed in anyconvenient protected location. Observe the recommendedenvironmental limitations for the Constant Volume Controller(see the Technical Data section of the product data sheet)when choosing a location.

The Constant Volume Controller may be mounted withoutremoving the controller from the mounting plate. The unit ismounted by four (4) screws in the corners. Select the correctscrews or other fasteners for the type of mounting materialbeing utilized.

FIGURE 10: CONSTANT VOLUME CONTROLLER

036-33035-001-A-1101


FIGURE 11: CONSTANT VOLUME CONTROLLER WIRING

Use extreme care not to damage any of the elec-tronic components while mounting the backplate.Mark the holes then remove the CV Controllerbefore drilling. Do not allow metal shavings to fallonto the circuit boards.

TIPAfter making all electrical connections it is advisedto unplug all terminal blocks on the CV Controlleruntil you are ready to begin the checkout procedure.This may help to prevent damage if wiring errorsoccur elsewhere in the system during installation orstart-up.

036-33035-001-A-1101


The Constant Volume Controller requires the following electrical connections:

18 Gauge minimum unless otherwise noted.

CONSTANT VOLUME CONTROLLER ADDRESSING

FIGURE 12: CV CONTROLLER ADDRESS SWITCH SETTING

-24VAC Supply Voltage 2 Conductors

-Communications Loop 2 Conductor twisted pair with shield(Belden #82760 or equivalent)

-Supply Air Temperature Sensor (24 ga. Min.) 2 Conductors

-Room Air Temperature Sensor (24 ga. Min.) 2 Conductors for standard sensor3 Conductors for sensors with setpoint adjustment

-Outside Air Temperature Sensor (24 ga. Min.) 2 Conductors

-HVAC Unit Control Wiring R - Common G - FanHeat / Cool Stage 1, 2, 3, & 4

036-33035-001-A-1101


ZONE SENSORS

The zone sensor uses a patented flush mount design to iso-late the temperature sensing element from the housing whichmounts flush with the wall surface.

Zone sensors should be located on an inside wall away fromdirect sunlight or heat producing equipment such as comput-ers, copiers, etc. Such devices can adversely affect the accu-racy of the sensor.

Although the sensor eliminates most of the effects of thermalcoupling to the walls, try to avoid walls which retain largeamounts of thermal energy (such as marble or steel). Wallscontaining either cold or warm air currents should also beavoided whenever possible.

Avoid locating the sensor in dead air areas of a room. Thiswill result in slow response to temperature changes in thespace.

Mount the sensor approximately 50-60 inches from the floorfor best results.

The zone sensor is designed to mount vertically in a standard2 by 4 inch electrical box. The sensor may be mounteddirectly into the drywall where electrical codes do not require

low voltage wiring to be enclosed in conduit. A template issupplied with the sensor to facilitate cutting a hole of the cor-rect size.

Connect the terminal labeled GND on the zone sensor to theterminal labeled GND on the Zone Controller terminal blockfor the TEMP SENSOR. Connect the terminal labeled TMPon the zone sensor to the terminal labeled TEMP on the ZoneController terminal block for the TEMP SENSOR. If the zonesensor has a setpoint adjust slider, then connect the sensorterminal labeled AUX to the Zone Controller AUX terminalblock labeled AUX1.

FIGURE 13: ZONE SENSOR WIRING

TIPBe careful when cutting the hole for the sensor orthe plastic bezel of the sensor may not completelycover the opening.

TIPIf sensors must be installed on walls which are solidand cannot be penetrated, surface mounted boxesand raceway can be purchased from your local elec-trical distributor.

GND

Room Sensor with OverrideAnd Adjustable Setpoint

Zone Controller

AUX

+VS

AUX1

AUX 2

GND

T'STAT

GND

TEMP

ADJUSTABLESETPOINT

OVERRIDE

WARMER

COOLER

NORMAL

OVR

GND

TMP

AUX

TB

036-33035-001-A-1101


SUPPLY AIR TEMPERATURE SENSOR

The supply air temperature sensor should be located asclose to the rooftop unit discharge as possible for bestresponse and mounted upstream of the bypass damper forbest results.

Locate the sensor in the center of the widest part of the duct.Use the supplied template and a 5/16" drill to make a hole forthe sensor. Install the gasket over the probe and mountsecurely to the duct using the supplied sheet metal screws.Be sure the gasket is compressed to provide an air tight seal.

For best accuracy, apply insulation on the outside of the duct,over the sensor. This will help prevent thermal gradients fromaffecting the sensor.

RETURN AIR TEMPERATURE SENSOR

The return air temperature sensor should be located asclose to the rooftop unit return air intake as possible. Avoidlocations which will be exposed to extreme outside tempera-tures.

Locate the sensor in the center of the widest part of the duct.Use the supplied template and a 5/16" drill to make a hole forthe sensor. Install the gasket over the probe and mountsecurely to the duct using the supplied sheet metal screws.Be sure the gasket is compressed to provide an air tight seal.

For best accuracy, apply insulation on the outside of the duct,over the sensor. This will help prevent thermal gradients fromaffecting the sensor.

OUTSIDE AIR TEMPERATURE SENSOR

The outside air sensor must be located where it will not beaffected by direct sun or heat producing equipment. Mountingunder the eve of a roof is often a good choice.

STATIC PRESSURE SENSOR

The static pressure sensor is designed to be mounted atthe controller, or on the ductwork near the pickup tube, andmay be connected via its modular plug. If the sensor ismounted on the ductwork, the modular plug must be cut offand 3-conductor wire spliced onto the sensor leads. The con-troller has a terminal block which is paralleled with the modu-lar jack to allow connection when this method is utilized.

Do not mount the return air sensor in the mixed airsection. This will cause an error in the reading.

Complaints of inaccurate outside sensor readingsare very common and can almost always be shownto be the result of poor sensor location

NOTEAll sensors utilize the same type thermistor sensorsensing element. Refer to Appendix Table 1, TEM-PERATURE SENSOR RESISTANCE CHART, fortroubleshooting sensor problems.

Mount the static pressure sensor on a vertical sur-face with the tube tips pointing downward. Avoid anykinks or sharp bends in the tubing which runs fromthe pickup tube to the sensor.

The plastic housing on the sensor is electricallyconductive. Avoid contact with any electrical com-ponents. It is acceptable to mount the sensor ongrounded sheet metal such as ductwork, electricalpanels, etc.

Use extreme care when mounting the sensor toavoid damage to the plastic housing.

Do not over tighten the mounting screws!

Do not use mounting screws which are too large forthe holes!

NOTERefer to Appendix Table 2 for instructions concern-ing proper location of the static pressure sensor.

036-33035-001-A-1101


FIGURE 14: STATIC PRESSURE SENSOR WIRING

AUXILIARY RELAY BOARD FOR ZONECONTROLLERS

An optional auxiliary relay board is available for the ZoneControllers. This board provides additional outputs for the fol-lowing applications:

• Parallel Fan

• Box Heat

• Auxiliary Heat (typically perimeter type)

• Series Fan

The board comes shipped with a modular cable which plugsdirectly into the Zone Controller connector marked “Expan-sion.” After connecting the board, the system will need to bepowered OFF then ON for the system to recognize the pres-ence of the relay board..

FIGURE 15: AUXILIARY RELAY BOARD LAYOUT

ZONE CONTROLLER RELAY EXPANSION BOARDOPERATION

Relay #1 - Parallel Fan

If the zone is in cooling mode or vent mode, the parallelfan can activate anytime the zone temperature drops 0.5°Fbelow the heating setpoint. It de-activates when the temper-ature rises above the heating setpoint.

Relay #2 - Box Heat

If the zone is in cooling mode or vent mode the box heat canactivate anytime the zone temperature drops 1.5°F below theheating setpoint. It de-activates when the temperature risesto within 1.0°F of the heating setpoint. Box heat is not allowedto activate in the heating mode when there is hot air beingsupplied by the air handler. This output was intended to allowzone re-heat while the Zone Manager is satisfying coolingdemands in other zones.

Relay #3 - Aux Heat

In the occupied mode, the aux heat can activate anytimethe zone temperature is 0.5°F below the aux heat setpoint.It de-activates when the temperature rises 0.5°F above theaux heat setpoint. In the unoccupied mode, the aux heatuses the unoccupied heating setpoint with the same dead-band values mentioned above. This prevents the zone frommaintaining the same aux heat setpoint at night that it doesduring the daytime.

This output was intended to allow zone heating, to augmentthe normal heating mode and also to allow a zone to attemptto satisfy its own heating needs before creating a heatingdemand at the Zone Manager.

Relay #4 - Series Fan

The series fan runs anytime the main fan is running. Thisincludes occupied and unoccupied modes. The fan can onlystart running when the zone damper is closed, so it firstmakes sure the damper is closed, before starting the fan.

COMMLINK II INTERFACE

The CommLink II Interface provides on site computer hook-up or modem interface for remote communications. TheCommlink II is wired as shown in Figure 16.

Relay contacts are rated for 24VAC pilot duty only!Do not apply voltages higher than 24VAC.

036-33035-001-A-1101


Locate the CommLink near the computer or modem. Thecable connections between the CommLink II and the com-puter or modem should be kept to less than twenty-five feet.

The CommLink II comes complete with computer and modemcables, and a plug-in power supply.

FIGURE 16: COMMLLNK INTERFACE WIRING

036-33035-001-A-1101


APPENDIX

*Notes:

1. Use the resistance column to check the thermistor sen-sor while disconnected from the controllers (not pow-ered).

2. Use the voltage column to check sensors while con-nected to powered controllers. Read voltage with meterset on DC volts. Place the "-" (minus) lead on GND termi-nal and the "+" (plus) lead on the sensor input terminalbeing investigated.

If the voltage is above 5.08 VDC, then the sensor or wir-ing is "open". If the voltage is less than 0.05 VDC, thesensor or wiring is shorted.

Table 1:Temperature Sensor Resistance Chart

TEMPERATURE

°FRESISTANCE

Ω*VOLTAGE AT

INPUT*

-10 93,333 4.620

-5 80,531 4.550

0 69,822 4.474

5 60,552 4.390

10 52,500 4.297

15 45,902 4.200

20 40,147 4.095

25 35,165 3.982

30 30,805 3.862

35 27,140 3.737

40 23,874 3.605

45 21,094 3.470

50 18,655 3.330

52 17,799 3.275

54 16,956 3.217

56 16,164 3.160

58 15,385 3.100

60 14,681 3.042

62 14,014 2.985

64 13,382 2.927

66 12,758 2.867

68 12,191 2.810

69 11,906 2.780

70 11,652 2.752

71 11,379 2.722

72 11,136 2.695

73 10,878 2.665

74 10,625 2.635

75 10,398 2.607

76 10,158 2.577

78 9,711 2.520

80 9,302 2.465

82 8,893 2.407

84 8,514 2.352

86 8,153 2.297

88 7,805 2.242

90 7,472 2.187

95 6,716 2.055

100 6,047 1.927

105 5,453 1.805

110 4,923 1.687

115 4,449 1.575

120 4,030 1.469

125 3,656 1.369

130 3,317 1.274

135 3,015 1.185

140 2,743 1.101

145 2,502 1.024

150 2,288 0.952

Table 1:Temperature Sensor Resistance Chart

TEMPERATURE

°FRESISTANCE

Ω*VOLTAGE AT

INPUT*

036-33035-001-A-1101


Table 2: Static Pressure Sensor Location Information

Preferred Location

If the trunk ducts are properly sized for minimum pressuredrop, the location of the static pickup probe is not particu-larly critical. It should ideally be located at right angles tothe airflow in a straight section of the supply duct approxi-mately 2/3 the distance of the total length of the supplyduct. Also the probe should be located not less than 3 ductdiameters downstream and 2 duct diameters upstream ofany elbow or takeoff.

Less Than Ideal, But Acceptable

Since the "ideal" location is often difficult to find in an instal-lation, a location in the main trunk where the tip is not in a"negative pressure area" (e.g. just downstream of the insidecurve of an elbow) or an area where the tube opening isdirectly impacted by the velocity of the supply air.

Least Desirable, But Acceptable

If the supply duct comes directly from the unit and immedi-ately splits in opposite directions, the pressure pickupshould be located ahead of the split, or as close to it as pos-sible, even if the bypass damper(s) are located downstreamof the split.

RETURN

RETURNAIR

SENSOR

SUPPLYTEMP

SENSORBYPASS

2DMIN.

3DMIN.

STATICPRESSURE

PICKUP

FAN

SENSING LINES ARE EQUALLENGTH AND SIZE

SUPPLYTEMP

SENSOR

STATICPRESSURE

PICKUP

TEE

TO ZONES TO ZONES

BYPASSRETURN

FAN

036-33035-001-A-1101


NOTES

Subject to change without notice. Printed in U.S.A. 036-33035-001-A-1101Copyright © by Unitary Products Group 2001. All rights reserved. Supersedes: Nothing

Unitary 5005 NormanProduct York OKGroup Drive 73069

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