Trane VariTrane Installation/ Owner Programming

Download

Installation/ Owner Programming

VariTrane™ Analog Electronic Controls

For use with:

Single-Duct Cooling & Reheat Units Parallel & Series Fan-Powered Units Low-Height Parallel & Series Fan-Powered Units

November 2001

VAV- SV X 0 3 A- EN

VAV-SVX03A-EN

Contents

General Information

Literature Contents ............................................................................................... 4

Receiving and Handling ......................................................................................... 4

Unit Information

Single-Duct Units ............................................................................................... 4-5

Fan-powered Units ............................................................................................ 4-5

Analog Controls

General Electonic Controls Installation Minimum and Maximum Potentiometers Adjustments Zone Sensor Wiring Location and Mounting

Sequence of Operation

Single-Duct Units .................................................................................................. 9

Series Fan-powered ............................................................................................. 9

Parallel Fan-powered ............................................................................................ 9

Control Options

Constant-Volume ................................................................................................ 10

Auto Dual Minimum ............................................................................................ 10

Calibration

Transducer Operation ..........................................................................................11

Null Voltage .......................................................................................................... 11

Procedure for Maximum and Minimum Calibration ..............................................11

Set Maximum Flow ..............................................................................................11

Set Minimum Flow .............................................................................................. 12

No Dual Minimum .......................................................................................... 12

Auto Dual Minimum ....................................................................................... 12

Balancing

Balancing Procedure ........................................................................................... 13

Adjustments (Set Maximum and Minimum Flows) .............................................. 13

Installation and Wiring Zone Sensor

Zone Sensor Operation ....................................................................................... 15

Troubleshooting

Tools and Equipment ........................................................................................... 16

System Check ..................................................................................................... 16

Air Damper and Motor Check .............................................................................. 17

Control Check ...................................................................................................... 17

Zone Sensor Check ............................................................................................. 17

Heater Contactor Check ...................................................................................... 17

Fan Motor Check ................................................................................................. 17

Circuit Board Check ............................................................................................. 17

Transducer Check ................................................................................................ 18

Triac Output Check .............................................................................................. 18

Auto Dual Minimum Check .................................................................................. 18

Electronic Zone Sensor Check ............................................................................. 19

VAV-SVX03A-EN 3

General Information

Literature Contents

This manual describes the operation, calibration and set-up of VariTrane VAV Single-Duct and Fan-powered units with Analog Electronic Controls.

Receiving and Handling

VariTrane units are shipped completely assembled with the exception of filters and accessories. Upon receiving, please inspect each unit and the components for shipping damage.

After receiving the units, complete the following:

 Locate the nameplate and model

number and check that the correct units have been received.

 Inspect the control units and air damper

casing for dents or punctures.

 Verify that all options have been

included, such as filters, controls, heating coils, water valves, etc. Also check that unit voltages agree with the building parameters.

 Manually rotate the fan (if applicable) to

assure that there are no obstructions within the housing.

 Claims for in-transit damage must be

filed immediately with the delivery carrier.

 For re-heat units, check the coil fins and

make sure the coils are not damaged.

 Locate and verify that the correct zone

sensors are with the order. These will be marked with an orange “Accessories Enclosed” label. Store in a secure place until needed. Accessories lost at a jobsite are NOT covered by Trane’s warranty.

 If a discrepancy occurs between what

was ordered and what is received, contact your local Trane representative immediately.

 Read the appropriate section in this

manual for installation procedures prior to actual starting of installation.

Warnings and Cautions appear at appropriate sections throughout this manual. Read these carefully.

WARNINGWARNING

avoided, could result in death or serious injury.

CAUTIONCAUTION

avoided, may result in minor or moderate injury.

CAUTION:CAUTION:

in equipment or property only damage.

4 VAV-SVX03A-EN

— May also be used to alert reader to a situation that could result

NOTICE:

— Indicates a potentially hazardous situation which, if not

Unit Information

Unit Type Description

Analog Electronic VariTrane units use an electronically-controlled air damper for primary air modulation. The unit types available are single-duct units (VCCF, VCWF, VCEF), series fan-powered units (VSCF, VSWF, VSEF), parallel fanpowered units, (VPCF, VPWF, VPEF) and low-height fan-powered units (LSCF, LSWF, LSEF, LPCF, LPWF, LPEF).

Single-Duct Units

The basic unit consists of an air damper mounted in a sheet metal casing, which is used to control the volume of air introduced to the occupied zone. The unit is designed to modulate either cooling or heating air. The basic coolingonly unit can be equipped with reheat coils located at the discharge of the unit. Standard choices include an electric coil with up to three stages of heat or a hotwater coil.

Figure 1 – Typical Single-Duct Units

VCCF

Fan-Powered Units

VariTrane fan-powered units can be either parallel or series, with or without re-heat. See Figure 2.

Note: Low-Height is similar to the series and parallel fan-powered units. All series and parallel references from this point on will also include Low-Height unless noted.

The fan on a series unit runs continuously whenever the main air-handler unit is in operation. There are various options for starting the fan. The fan can be started three ways: 1) remotely,

2) by a duct-pressure switch, or 3) by a combination of both. The particular fan control method will vary from unit to unit, depending upon job needs.

Typically, the re-heat is off while the air damper modulates primary air and responds to zone temperature. If zone temperature decreases to the point where a decrease in primary air will not maintain the desired temperature, the re-heat will be activated to increase the temperature of the discharge air.

On a parallel unit, the VariTrane air damper delivers primary cooling air to the unit outlet. When the space temperature decreases beyond air damper control, the fan is turned on as the first stage of heat. The fan delivers

plenum air from above the occupied space to the unit outlet, which is mixed with primary air and delivered to the occupied space.

Note: Either the fan, the air damper or both can deliver airflow into the occupied space. In order to prevent primary airflow from exiting through the fan when the fan is not running on a parallel unit, a back-draft damper is provided. When the fan is not running, the efficiency of this system is the same as a standard single duct VAV unit.

Typically, the control systems applied to parallel units cause the air damper to close to zero or a minimum flow before the fan is activated. After the fan is activated, the heat will be activated upon further reduction in zone temperature. Therefore, little primary air is mixed with the heated air.

Fan-powered units are available with rectangular discharge connection only. Either straight flange or slip and drive is available with electric heat. The electric heater is mounted on the discharge of the unit. Hot water coils are connected to the plenum inlet on parallel units, and to the discharge of series units.

VCWF

VCEF

VAV-SVX03A-EN 5

Table 1 – Maximum Fan Motor Amperage (FLA)

Fan HP 115 277 347 208

Size VAC VAC VAC VAC

Series/Parallel 01 1/8 1.6 0.7 0.7 — Series/Parallel 02 1/8 1.6 0.7 0.7 — Series/Parallel 03 1/3 5.4 1.8 1.5 — Series/Parallel 04 1/3 5.4 1.8 1.5 — Series/Parallel 05 1/2 7.6 2.6 2.1 — Series/Parallel 06 1/2 — 3.8 3.8 6.3 Series/Parallel 07 1 — 4.7 3.6 6.9

Low Height 08 1/8 4.7 1.76 1.52 — Low Height 09 2 x 1/8 2 x 2.1 2 x 0.79 2 x 0.62 — Low Height 10 2 x 1/8 2 x 4.7 2 x 1.76 2 x 1.52 —

Figure 2 – Typical Fan-Powered Units

VSCF VSWF

Unit Information

VSEF

VPCF VPWF

VPEF

6 VAV-SVX03A-EN

Analog Controls

General

Electronic control systems offer pressure-independent operation for use on all single-duct and fan-powered VAV units (see Figure 3).

The electric air damper used with this control system has a stroke time (from open to close) of 90 seconds.

The pressure-independent system will control room temperature by adjusting airflow into the space as a function of zone temperature.

Figure 3 –Electronic Interface Circuit Boards

Electrical Data

INPUT: 24 VAC, 50 VA maximum

OUTPUT:

Stage – 24 VAC, 10 VA magnetic

1 contactors/12 VA mercury contactors

Stage – 24 VAC, 10 VA magnetic

2 contactors/12 VA mercury contactors

Stage – 24 VAC, 10 VA magnetic

3 contactors/12 VA mercury contactors

Cfm Requirements

Control Unit Cfm Flow Cfm Flow Cfm Flow Setting

Type Size Setting Setting (VCEF Only)

4 38-225 0,38-225 45-225 5 63-350 0,63-350 70-350

Analog 8 134-900 0,134-900 180-900

Electronic 10 215-1400 0,215-1400 280-1400

Notes:

1. Minimum flow and maximum flow settings must have at least a 0.05 Delta P flow sensor signal difference.

2. Flow rings are provided with all unit sizes.

3. A minimum setting of zero is permissible, except for VCEF units.

6 73-500 0,73-500 100-500

12 300-2000 0,300-2000 400-2000 14 408-2890 0,408-2890 578-2890 16 536-3790 0,536-3790 758-3790

24x16 1096-8000 0,1096-8000 1600-8000

Maximum Minimum Minimum Heating

WARNINGWARNING

Hazardous Voltage!

Disconnect all electric power, including remote disconnects before servicing. Follow proper lockout/tagout procedures to ensure the power cannot be inadvertently energized. Failure to disconnect power before servicing could result in death or serious injury.

Electronic Controls Installation

Check the wiring on the unit with the wiring diagram and wiring information label. Insure that all jumpers are to the proper location and that the actual unit wiring matches the wiring diagram and wiring label information. See Figure 4.

Units with electronic control options must use Trane zone sensors to be compatible with the unit circuitry. The analog zone sensor electronics are designed

specifically to operate with the Trane electronic controls; other zone sensors will not work properly with this unit. The Trane analog zone sensor must be used in conjunction with these electronic controls. Typically, field

controls wiring include the following:

1. 24 VAC-powered connection to terminals TB1-1 and TB1-2. These are stab terminals marked one and two on the five-pole terminal strip located in the corner of the circuit card.

2. Zone sensor connections are to TB1-3,4,5.

3. Heater contact wiring is normally installed in the factory. Should field installation be required, each wiring diagram shows the field alternate wiring requirements.

VAV-SVX03A-EN 7

Analog Controls

Figure 4 – Typical Analog Electronic Control Wiring Diagram

CAUTION:CAUTION:

Avoid Wiring Errors!

It is important to connect power and zone sensor control voltage wiring to the proper terminals since improper connection will cause failure of the circuit board. To help prevent errors, the 24 VAC power to circuit board zone sensor connections are labeled.

Minimum and Maximum Potentiometers Adjustments

The minimum and maximum flow (or position) setpoints may require field setting to obtain desired cfm settings. Refer to the calibration section of this manual for proper adjustment procedures.

On single-duct boxes where transformers are optional, the transformer must be NEC Class 2, energy-limiting, 24 VAC. Refer to electrical data for proper sizing.

WARNINGWARNING

Hazardous Voltage!

Zone Sensor Wiring

Each unit must be controlled by a wallor unit-mounted zone sensor which is designed specifically for use with a solid-state circuit board that is provided by the factory.

Two types of zone sensors are available with analog electronic controls. One has the thumbwheel visible, while the other is hidden by the cover.

NOTE: Analog electronic zone sensors are not interchangeable with DDC zone sensors.

The three wires required for the wall zone sensor to the terminal block are to be furnished and completed by the installer.

If local codes require enclosed conductors, the zone sensor wires should be installed in conduit. Do not route zone sensor wires in conduit with 24-volt or any high-powered conducting wires. This will cause electrical noise and result in erratic operation of the controls.

CAUTION:CAUTION:

Circuit Board Damage!

Before handling the circuit board, discharge any static electricity you may have accumulated by touching the unit casing. Static charges produce voltages high enough to damage the electronic components.

Location and Installation

A zone sensor in each control zone should be located in the most critical area of the zone. Sensors should not be installed in direct sunlight or in the area’s supply air stream. Subdivision of the zone may be necessary for adequate control and comfort.

Avoid installing zone sensors in areas subject to the following:

 Drafts or “dead spots” behind doors

or corners.

 Hot or cold air ducts.  Radiant heat from the sun or

appliances.

 Concealed pipes or chimneys.  Unheated or uncooled surfaces behind

the sensor such as outside walls.

 Air flows from adjacent zones or

other units.

8 VAV-SVX03A-EN

Sequence of Operation

Single-Duct Units

The air damper is controlled between minimum and maximum flow setpoints proportionally. When the zone temperature is approximately 0.5°F above the setpoint, the air damper will begin to modulate to a maximum position, providing more cool air to the zone until the zone temperature reaches the zone setpoint. Once satisfied, the air damper will start to modulate to the minimum position. When the zone temperature is

0.5°F below the setpoint, the damper begins to modulate to a minimum position. When the damper is at the cooling minimum and the zone temperature is still below setpoint (cold), up to three stages of heat may be energized on a reheat unit. The first stage is activated at approximately 2°F below the setpoint, the second stage is activated approximately 3°F below the setpoint, and the third stage is activated approximately 4°F below the setpoint.

Series Fan-Powered Untis

The series fan-powered unit is a constant volume, variable temperature device. The fan is energized whenever the zone is occupied. It delivers design cfm regardless of the load. The air damper controls primary air proportionally between minimum and maximum flow setpoints. When the zone temperature is approximately

0.5°F below the setpoint, the damper begins to modulate to its minimum position, supplying less cold air and more warm plenum air. When the air damper is at minimum and zone temperature is still below setpoint (cold), up to two additional stages of electric heat may be energized. On an electric reheat unit, the first stage is activated approximately 2°F below the setpoint. The second stage is activated approximately 3°F below the setpoint. On Hot Water Reheat just one stage of heat, in addition to the fan, will be activated approximately 2°F below the setpoint.

Parallel Fan-Powered Units

The parallel fan-powered unit is a variable-volume, constant-temperature device at high cooling loads and a constant-volume, variable-temperature device at low cooling and heating loads. The air damper controls primary air proportionally between minimum and maximum flow setpoints. When the zone temperature is approximately

0.5°F above setpoint, the air damper will begin to modulate to a maximum position, providing more cool air and less plenum air to the zone until the zone temperature reaches the zone setpoint. When the zone temperature is approximately 0.5°F below the setpoint, the damper will begin to modulate to a minimum position, reducing the cooling capacity. If the cooling capacity is reduced and zone temperature is still below the heating setpoint, the fan will be energized at approximately 2°F below the cooling setpoint acting as the first stage of heat. The second stage of heat (electric or hot water) is activated at approximately 3°F below the cooling setpoint and the third stage (electric) is activated at approximately 4°F below the cooling setpoint.

VAV-SVX03A-EN 9

Control Options

CONTROL OPTIONS

Constant Volume

With this feature, when jack J15 Pin A is connected to Pin B, the electronics will cause the airflow to go to the maximum setting and stay there. The influence of the thermostat is removed and maximum flow is maintained at all times. The operation of the three reheat relays is unaffected. Connecting Pins A and B of jack J15 will only affect the signal which goes into the section of the electronics which controls the air damper movement. The maximum flow option is obtained by saturating the temperature voltage signal so that the maximum limit is always sent on to the section of the electronics, which compares the temperature voltage to the flow voltage.

Auto Dual Minimum

The auto dual minimum enables the unit to change the minimum automatically without an outside signal. The minimum changes when the first stage relay is activated. The electronics have been designed so that when jack J18 Pins A and B are connected together, Minimum B (Potentiometer R69) will control whenever the first relay stage activated. Therefore, no matter what minimum was in control before the relay stage was activated, after being activated, Minimum B (R69) will be the determining minimum flow. This option can be used effectively with fanpowered units where a minimum flow is set as the damper modulates and when the first stage comes on, the air damper is then closed. In this manner, airflow to the space is never interrupted; however, the energy associated with maintaining a minimum air damper airflow at all times is saved.

10 VAV-SVX03A-EN

Calibration

The following tools are required to properly adjust and calibrate the electronic controls:

 Digital voltmeter  0-2 in. wg magnehelic gage (or inclined

manometer)

 Tubing and fitting to connect gage to

flow ring tees (5/32" and 1/4" tubing).

 Mechanical tools (screwdriver,

pliers, etc.)

WARNINGWARNING

Hazardous Voltage!

Certain tests or calibration procedures described in this section may involve working in close proximity to live electrical terminals. Only qualified and licensed electrician or other properly trained in electrical safety when working with live voltage should perform these procedures. Failure to follow all electrical safety precautions when exposed to live terminal could result in death or serious injury.

Transducer Operation

This section discusses how airflow through the damper is transformed into a voltage signal that can be used by the controller. The first transition from flow to voltage occurs at the Trane flow ring, where a delta P signal is generated as a function of airflow through the unit. The delta P signal consists of a highpressure signal from a total-pressure tap of the airflow ring and a lowpressure signal from the wakepressure side of the flow ring.

The transducer converts the pressure differential signal to an output voltage. The output of the transducer with no flow or zero delta P is .250 volts DC (+ .100). As flow increases, the delta P signal increases; therefore, the output voltage of the transducer increases. The gain of the transducer is 0.75 volts per inch of delta P.

Null Voltage

The tolerance for the output voltage of the transducer with zero delta P signal from the flow ring is referred to as the null voltage of the transducer. The transducer has three wires leading from it to the control board. The wires include a common (green wire), an input (red wire), and an output (black wire). The input (supply) voltage to the transducer is 5 volts (+ .5). The acceptable voltage range of the output voltage with zero flow (between black and green) can range from .100 volts to .400 volts. To allow the controllers to coordinate with the transducer voltage, internal calibration is necessary. To accomplish this, potentiometer R8 (zero flow adjustment) is used. The flow voltage signal should be 4.8 volts at test points #1 and #3 of the test point terminals (next to R8) with zero delta P applied. R8 is used to adjust the flow voltage to 4.8 volts when zero delta P is applied to the transducer. In this manner, variability of the null point of the transducer is compensated for. The importance of this becomes evident when minimum and maximum flows are discussed.

PROCEDURE FOR MAXIMUM AND MINIMUM CALIBRATION

Initialization

1. Monitor thermostat voltage and check it by rotating the thermostat to full heating and full cooling.

a. Connect a voltmeter to TB1-4 (+)

and TB1-3 (-).

b. Rotate the thermostat fully

clockwise (full heating). Observe the voltage. It should be less than or equal to 5.4 volts DC.

c. Rotate the thermostat fully

counter-clockwise (full cooling); voltage should go up to 6.3 volts DC or greater.

2. Set the min/max pots as follows: a. Rotate the max pot (R67) full

clockwise.

b. Rotate min A (R68) full counter-

clockwise

c. Rotate min B (R69) full counter-

clockwise

3. With both of the transducer ports open

to ambient (0 delta P), read the output voltage at TP4. (Ground is either TP3, TB1-2, or TB1-3.) The value of the null transducer voltage output must be between 0.1 and 0.4 volts DC. Nominal is .250 volts DC.

4. Monitor TP1 (+) voltage (zero flow

adjustment) and adjust R8 until 4.8 volts DC + .010 volts is read at TP1.

Set Maximum Flow

Set the thermostat knob to the full-cool position (fully counter-clockwise) thermostat voltage should go over 6.2V DC. Connect a pressure gage teed into the high- and low-port flow ring of the transducer and input the maximum delta P. Refer to the flow vs. delta P chart on the unit to obtain the proper delta P signal desired. Adjust the max pot (R67) so that both the amber and green lights are out, this indicates that equilibrium has been established with the delta P input to the transducer.

VAV-SVX03A-EN 11

Calibration

Set Minimum Flow(s)

In this section, two procedures for setting minimums will be discussed.

No Dual Minimum

Adjust the thermostat knob to the fullheat position (full clockwise). Monitor the delta P of the transducer with a pressure gage (high port first and low port). Refer to the calibration label on the side of the unit, which relates CFM to delta P. Adjust R68 (minimum A) so that both the red and green lights are out at the desired minimum flow delta P. If the minimum setting is to be zero flow, then leave the minimum pot (R68) full counter-clockwise so that the red light remains on even when no delta P is

applied to the transducer. This will ensure that the unit will always go to closed when minimum is desired.

Auto Dual Minimum

Place jumper on J18-A to B. The heating minimum is the minimum

at which the damper is controlled to when the fan on a fan-powered unit is activated or when the first relay is activated on a reheat unit.

Set the thermostat to the full-heat position (full clockwise).

Adjust minimum potentiometer R69 (Minimum B) to desired heating minimum. If this setting is to be zero, leave the potentiometer fully counter-

clockwise so that the amber light remains on with no delta P applied to the transducer.

Remove the jumper from J18-A to J18B. This puts the unit into the mode where minimum A is now in control (cooling minimum).

Adjust R68 (Minimum A) when both lights are off when the condition is satisfactory. If zero minimum is desired, leave pot R68 full counter-clockwise so that the amber light is on continuously with zero delta P applied to the transducer.

Replace J18 jumper.

12 VAV-SVX03A-EN

Balancing

The following tools are required to properly adjust and calibrate the electronic controls:

 Digital voltmeter  0 to 2 in. wg magnehelic gage  Tubing and fitting to connect gage to

flow ring tees.

 Mechanical tools i.e. screwdriver,

pliers, etc.

Balancing Procedure

1. Check the 24-volts AC supply voltage to the circuit card, terminals TB1-1 to TB1-2. Acceptable range =

21.6 to 26.4 volts AC.

2. Check the 12-volts DC power supply of the circuit card terminals TB1-5 (+) to TB1-3 (-). Acceptable range = 11.6 to

12.4 volts DC.

3. Install the magnehelic gage to observe delta P. When connecting to the test tees, be careful not to create an excessively low pressure on the transducer (when used). The following procedure should be followed:

a. Remove low-pressure cap from

test tee.

b. Remove high-pressure cap

from test tee.

c. Connect gage to high-

pressure side.

d. Connect gage to low-

pressure side.

Adjustments (Set Maximum and Minimum Flows)

To set minimum and maximum flows to the desired setting, refer to the calibration section.

VAV-SVX03A-EN 13

Installation and Wiring

The general layout of the analog circuit board is shown in Figure 5. The layout of the circuit card shows the physical location of each item. Basic connections are as follows (see Figure 4, page 7):

Figure 5 – Analog Electronic Controller

1. Power is connected to TB1-1 and TB1-

2. The power requirement is 24 volts AC (+ 10%).

2. The zone sensor is connected to terminals TB1-3, 4, and 5. It is very important not to connect power to these terminals, since applying power to the wrong terminal will destroy the card.

3. The motor is connected via jack J1.

4. The transducer (pressureindependent) is connected at jack J3.

5. Reheat stages (or fan on fan-powered units) are connected at jacks J7 (24 VAC), J9, J10, and J11.

6. Various options to cause changes to the operation of unit are input at jack J15.

7. There are various adjustments on the circuit card as discussed in detail in the Calibration section.

a. Maximum flow (or position)

adjustment is R67. Turning clockwise increases the maximum flow.

b. There are two minimum flow

adjustments labeled R68 and R69. Turning clockwise increases the minimum flow.

c. There is a zero-flow adjustment

used in initial calibration and setup of the circuit card. This is R8.

8. There are four test points for the convenience of servicing in the field. These test points include:

 TP4: Transducer output  TP1: Flow voltage (null calibration)  TP2: Temperature voltage  TP3: A common to make application of

clip leads easy.

14 VAV-SVX03A-EN

Zone Sensor

Zone Sensor Operation

This section explains how the zone sensor operates.

Temperature is sensed using a thermistor. The thermistor changes resistance with a change in temperature. The resistance of a thermistor decreases as temperature increases. By using a voltage divider circuit, the deviation from the room setpoint is determined.

1. 12-volts DC is supplied from TB1-5 on the circuit card to terminal 1 on the zone sensor.

2. The zone sensor output signal is connected from terminal 2 of the zone sensor to TB1-4 on the circuit card.

3. A common (ground) is supplied from TB1-3 on the circuit card to terminal 3 on the zone sensor. At setpoint, the input to the circuit card is 6 volts measured across terminals 2 and 3. Therefore, with 12 volts input between terminals 1 and 3, the voltage drop across the thermistor will equal the voltage drop between terminal 2 and

terminal 3. With the voltages being equal, the room temperature is considered satisfied and all output relays are de-energized. If the temperature in the zone goes up, the resistance of the thermistor will go down, causing a voltage increase, which will drive the air damper open. Conversely, if the room temperature goes down, the thermistor resistance goes up, causing a decrease in the output signal, which will drive the air damper to minimum and energize the relay output. To determine the setpoint, the setpoint potentiometer is moved, changing the resistance between terminals 2 and 3. By changing the setpoint potentiometer, the temperature at which the output signal equals 6 volts will be changed. Therefore, the setpoint potentiometer moves the setpoint up and down.

Degrees Fahrenheit Thermistor Nominal Resistance (Ohms)

65 4070 66 3960 67 3850 68 3750

69 3660 70 3580 71 3500 72 3420

73 3330 74 3250 75 3170 76 3080

77 3000 78 2940 79 2870 80 2810

VAV-SVX03A-EN 15

Troubleshooting

Symptom Probable Cause Recommended Action

Fan not running Faulty connection Check wiring diagrams and inspect all connections.

Incorrect voltage input Compare actual voltage with supply requirement.

Fan motor noise Incorrect voltage input Compare actual voltage input with supply requirement.

Low cfm to unit Supply fan not providing Adjust supply fan speed. Check for proper rotation.

Improper cfm to zone Debris is jamming valve Clear valve damper travel.

Incorrect air temperature Incorrect wiring to reheat coil Check and replace if necessary. Compare wiring with diagram on unit. delivered to the zone

Coils do not engage on Faulty relay or Triac Check for voltage to heating coil and relay(s). Verify supply voltage matches coil voltage. Call for heat

Room temperature differs Erratic zone sensor Check zone sensor voltage 12-volts DC between terminals 1 and 3. Check DC voltage at zone sensor from reading on zone terminal 2 and 3 (6 volts DC). Turn zone sensor to full heating voltage; it should be equal to or less Sensor (PI) than 5.4 volts DC. Turn zone sensor to full cooling voltage should be equal to or greater than 6.5 volts

Faulty fan motor Check motor and power to the fan motor. If power is present and fan does not run, replace the motor.

Loose fan wheel Adjust and tighten fan wheel

adequate cfm Leaky duct work Repair leak. Dirty Filters Replace air filters

Damage to valve casing Repair casing or replace valve. Improper wiring Check unit diagrams for correct connection. Faulty circuit board Check and replace if necessary. Faulty valve motor Check and replace if necessary. cfm setting incorrect Recalibrate circuit board.

Faulty zone sensor Check for correct zone sensor resistance. Faulty circuit board Recalibrate and replace if necessary. Incorrect supply air temperature Check leaving air temperature from air handling unit.

Board not calibrated Calibrate.

DC. If DC voltage is not attainable, replace the zone sensor.

Zone sensor miscalibrated. Check calibration of zone sensor. See also calibration section.

Tools and Equipment

When repairing a VariTrane product (analog control), it is important to have the necessary tools and instruments.

1. 0-2" magnehelic gauge with fittings for two ¼" outside diameter (OD) tubing

2. Voltmeter

3. Four jumper leads

4. Small screwdriver 1/8" blade

Hazardous Voltage!

16 VAV-SVX03A-EN

WARNINGWARNING

Troubleshooting

System Check

Improper room control may be caused by areas other than the VAV boxes. Before replacing the air damper or control box, make sure that the entire system is operating properly and is supplying sufficient air to the damper. Complete the following checks.

1. Look for obvious leaks in the duct system. Assure that sufficient static pressure is present at the air Damper.

2. Inspect the supply fan and VAV fan filters. Clean or replace, if necessary.

3. Check zone sensor location, outside wall, appliances, direct sunlight or the supply air stream may be artificially heating or cooling the zone sensor.

4. Evaluate diffuser should have 15" of flat ceiling surface on either side of the slot to assure proper air distribution. Check that airflow from grills or diffusers is properly balanced.

5. For accurate flow control, there must be at least two duct diameters of straight ductwork before the air damper inlet. Electric coils require four feet of straight ductwork downstream of the coil.

6. Compare voltage requirements, as specified on the side of unit with actual voltage supplied to the unit. The control voltage requirement is 24-volts AC + 10%.

Air Damper and Motor Check

If problems occur with damper actuation, perform the following steps:

1. Visually inspect the damper for loose gaskets, casing damage, or restriction to damper travel.

WARNINGWARNING

Hazardous Voltage!

2. Be sure that there is proper voltage supplied by checking for 24 volts at terminal 1 and 2 on the circuit board. Acceptable voltage range is 21.6 to

26.4-volts AC.

3. To open the damper, apply 24-volts AC to the white and green wires on the motor plug coming from the actuator. The drive takes a maximum of 90 seconds to fully open.

4. To close the damper, apply 24-volts AC to the white and red wires on the motor plug coming from the actuator.

5. If the motor fails to operate from a direct 24-volts AC power source, and there is neither binding nor obstructions, then the actuator is defective and should be replaced.

Control Check

WARNINGWARNING

Hazardous Voltage!

1. Disconnect power source and remove zone sensor wires 3, 4, and 5. Be sure to mark the wires so that they will be correctly replaced.

2. Reconnect power to the unit. The damper should move to its minimum or fully closed position.

3. Jumper terminals 4 and 5. The green LED should light. This should cause the damper to move fully open or to its maximum flow setting.

4. Disconnect the jumper from terminals 4 and 5.

5. Jumper terminals 3 and 4. The amber LED should light. The damper should close to minimum and the relays (or reheat) should energize.

6. Remove Jumper terminals 3 and 4.

7. If everything operates correctly, disconnect power and reconnect all wires. Check the air damper or zone sensor for further trouble analysis.

Zone Sensor Check

To troubleshoot the zone sensor, make sure that 24 volts are available at the control unit board and then complete the following procedure:

1. Move the zone sensor to full cooling. The damper should open completely. If the action is reverse, check the proper zone sensor connection.

2. Rotate the zone sensor knob to full heat. This should cause the damper to close and fan to come on. When the room setpoint is above the actual room temperature, stages of heat will be energized, if enabled.

3. If the zone sensor does not operate at all, check the wiring from the board to the sensor. Reference the zone sensor section.

4. Check DC voltage at zone sensor terminals 2 and 3 (6-volts DC). Turn the zone sensor to full heating voltage; it should be equal to or less than

5.4-volts DC. Turn the zone sensor to full cooling; voltage should be equal to or greater than 6.5-volts DC.

Heater Contactor Check

To troubleshoot heater contacts on units with electric reheat, complete the following procedure:

1. Disconnect power source.

WARNINGWARNING

Hazardous Voltage!

2. Disconnect wires from the contactor.

3. Connect an ohmmeter to the contacts.

4. Apply 24 volts (from independent power supply) to the coil of relays. Check for contact closure. If the contact does not close, replace the contactors.

VAV-SVX03A-EN 17

Troubleshooting

Fan Motor Check

To troubleshoot the fan motor, complete the following procedure:

1. Disconnect the power, check all wiring diagrams provided on the unit.

2. Turn the power back on. Operate the zone sensor to see if the proper voltage is being supplied to the motor relay. If the motor does not start, check the capacitor and fan motor.

3. Check the motor relay by attaching a voltmeter across the 24-volt coil of the relay. For parallel fan-powered, operate the zone sensor to energize the fan and confirm the voltage to the relay is turned on. Check for supply voltage between the common and hot side of the relay.

4. Attach a Voltmeter to the white common wire on the terminal block and the blue, black or red wires from the fan motor. If line voltage is present, check for fan obstruction.

5. With the power off, spin the fan wheel. If it does not run freely, check shaft alignment or housing clearances.

Circuit Board Check

1. Remove the control box cover. Inspect all wiring and compare with the label on the control box cover. The label also indicates jumper connections. Make sure that all wiring and jumpers are connected exactly as shown on the diagram.

2. Measure the voltage a terminals TB1 –1 (+) and TB1 –2 (-) on the circuit board. The voltage reading should be 24-volts AC +/- 10%.

3. Measure the voltage at terminal TB1-5 (+) and TB1-3 (-) on the circuit board. Voltage reading should be 12-volts DC + 10% tolerance. This voltage is the output power for the zone sensor. If these voltage readings are not shown, it could indicate a defective board.

4. If 12-volts DC is present, rotate the zone sensor thumbwheel and check for voltage change across zone sensor terminals 2 and 3.

5. Adjust the minimum fully counterclockwise and the maximum fully clockwise.

6. Verify the amber and green lights change when rotating the thumbwheel.

7. If any step does not work, replacement of the board may be necessary. If all steps work, proceed with further component checks.

Transducer Check

1. Disconnect the tubing to the flow sensor, remove the low-pressure line first, then the high side. Transducer damage may result if procedure is not followed.

2. Attach the voltmeter to terminals TP4 (+) and ground, B1-2 or 3, or TP3. Voltage on these terminals should be between .1- to .4-volts DC; the ideal is .254 volts DC.

WARNINGWARNING

Hazardous Voltage!

3. Connect the voltmeter to terminals TP1 (+) and ground. Voltage at these terminals should be 4.78 to 4.82 volts DC. If the voltage at these terminals is lower or greater than the specified tolerance, this could be the cause for not obtaining correct minimum or maximum flow. This causes the controller to not operate within the specified minimum and maximum values, even with the minimum potentiometer fully counter-clockwise. Adjust R8 for 4.8 volts DC.

4. Reconnect the air valve actuator and drive to maximum position. Voltage should increase on TP4 to TP3.

5. If voltage does not increase, verify with a magnehelic that the delta P is increasing.

6. Replace the transducer if delta P increases and voltage does not change.

Note: A faulty transducer will cause the air damper to function improperly.

Triac Output Check

1. Make sure that the zone sensor operation is correct and, if applicable, which zone sensor is under control. Refer to prior sections for step-by-step procedures.

2. Remove all connections from J9, J10, and J11. In addition, remove J19 if it is a series fan-power unit.

3. Set the zone sensor to the full cooling position.

4. Place a 500-1000 ohm resistor between the connectors J7 and J9 and measure the voltage between these points. It should be less than 10 volts AC.

5. Slowly increase the zone sensor setting from full cooling to heating. At a position on the zone sensor near room temperature, Triac #1, which connects J7 to J9 should close. Next, Triac 2, which connects J7 to J10, should energize and finally Triac 3, which connects J7 to J11, should energize. When the zone sensor is rotated to the full heating position, a voltage check should show that contact closures between J7 and J9, J7 and J10, and J7 and J11 have been made (closed).

6. If continuity is not present at all stages, replace the board.

Auto Dual Minimum Check

A digital voltmeter will be required to make the voltage checks described in this procedure. Note the following differences in labeling of adjustment potentiometer described in the following steps:

Circuit

Board

Label

R8 Null Voltage Calibration R67 Max Flow R68 Min Flow A R69 Min Flow B

1. Refer to calibration setup steps 1 through 4. Make changes as described in the following steps:

2. Rotate the zone sensor to the full cool position. The green LED should be illuminated on the circuit board and voltage present at terminals J1-3 to J1-1. The voltage at terminal TP2 to ground should be 5.9 volts DC or higher.

18 VAV-SVX03A-EN

Troubleshooting

3. Slowly rotate the zone sensor until the amber LED on the circuit board illuminates. Voltage at terminal TP2 to ground should be approximately

3.2 volts DC.

4. Continue rotating the zone sensor until the first stage of heat energizes. This can be determined by voltage across terminals J7 to J9. At this point, the green LED on the circuit board should illuminate. Voltage at terminal TP2 to ground should be 3.9 volts DC or higher. R68 should be in control.

5. Now adjust the zone sensor so that the output voltage at terminals 2 and 3 is

6.0 volts DC, +.01 volts DC, -.01 volts DC.

6. Compare the actual zone sensor to the indicated setpoint on the dial of the zone sensor. If the two readings are within 3°F of each other, then the zone sensor is within standard calibration tolerance. Calibration procedures are described in the Calibration Section in this manual.

7. Note position of R69. Rotate potentiometer R69 clockwise and counter-clockwise while watching the amber and green LED’s to make sure that the control is now with minimum potentiometer R69.

8. Return R69 to its original position.

Electronic Zone Sensor Check

Note: The following checkout procedures will be used when power is applied to the electronic zone sensor.

1. Room temperature must be between 65°F and 80°F. Make sure also that placement of the zone sensor is satisfactory. It should not be located in direct sunlight, on cold or hot wall surfaces, etc. A zone sensor or other accurate temperature measuring device should be installed next to the zone sensor. It is preferable to mount the temperature sensing element under the zone sensor cover next to the thermistor of the zone sensor. (the Thermistor is a small electronic temperature sensing device imbedded in a glob of silicone cement.)

2. Remove the zone sensor cover.

3. Attach a volt meter to terminals 2 (+) and terminal 3 (-).

4. Record temperature in zone. It should be between 65°F and 80°F.

5. Check the voltage a terminals 2 (+) and terminal 3 (-). If the zone temperature and the zone sensor setpoint are at equilibrium, the voltage at this point should be 6.00-volts DC.

6. Rotate the zone sensor to the fullheating position. Allow five minutes for the zone sensor to equalize setpoint. The voltage on terminals 2 and 3 should drop to 5.5-volts DC or less.

7. Rotate the zone sensor to the full cooling position. The voltage on terminals 2 and 3 should rise to

6.3-volts DC or higher.

Jack Numbering Designations for Analog Control Boards

Jack Function

J1 Motor J3 Transducer

J9 Stage 1 Contact J10 Stage 2 Contact J11 Stage 3 Contact J15 Drive MAX (constant volume) J18 Auto Dual Minimum J19 Output Override

TB1 Field Connections: Power and Zone

Sensor

VAV-SVX03A-EN 19

The Trane Company An American Standard Company www.trane.com

For more information contact your local district office of e-mail us at comfort@trane.com

Literature Order Number VAV-SVX03A-EN File Number SL-TD-VAV-000-SBX03A-EN-1101 Supersedes New Stocking Location La Crosse

Since The Trane Company has a policy of continuous product and product data improvement, it reserves the right to change design specifications without notice. Only qualified technicians should perform the installation and servicing of equipment referred to in this publication.

Trane VariTrane Installation/ Owner Programming

Specifications and Main Features

Frequently Asked Questions

User Manual