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48FK,JK034-104
48FM078-104
50FK,FY,JK,JY034-104
50FM,FS078-104
Variable-Air Volume Rooftop Units
Controls Operation,
and Troubleshooting
CONTENTS
Page Page
Control From Remote Building Management
SAFETY CONSIDERATIONS. . . . . . . . . . . . . . . . . . . . . . 2
System (BMS). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-13
OCCUPIED/UNOCCUPIED
Rooftop Information. . . . . . . . . . . . . .
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handling, rigging, and setting this equipment, and in handling CONTENTS (cont) all electrical components. Page TROUBLESHOOTING. . . . . . . . . . . . . . . . . . . . . . . . . 44-60 Checking Display Codes . . . . . . . . . . . . . . . . . . . . . . . . 44 Complete Unit Stoppage . . . . . . . . . . . . . . . . . . . . . . . . 44 Electrical shock can cause personal injury and death. Shut Single Circuit Stoppage . . . . . . . . . . . . . . . . . . . . . . . . . 44 off all power to this equipment
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The VAV control system monitors and controls the follow- Several status switches are also monitored. These switches ing functions of the rooftop unit: are connected to the processor at pin terminal connector J2. See Fig. 3 and Table 2. supply-air temperature (unit capacity) morning warm-up or electric heat (if equipped) In addition to the unit status switch inputs, the processor head pressure control, fan cycling board also accepts inputs from several potentiometers. These economizer pos
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LEGEND CR — Control Relay Enthalpy Control LEGEND EC — LPS — Low-Pressure Switch T— Thermistor Field Wiring Fig. 3 — Pin Terminal Connector J2 Accessory Status Switch Inputs Fig. 2 — Pin Terminal Connector J1 Thermistor Inputs Table 2 — Pin Terminal Connector J2 Status Switch Inputs CONNECTOR J2 UNIT SIZE STATUS SWITCH TERMINAL NO. 034-104 Oil Pressure, 1,2 Jumpered Circuit 2 Oil Pressure, Jumpered 3,4 Circuit 1 Loss of Charge, 7,8 LPS2 Circuit 2 Loss of Charge, 9,10
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All of the potentiometers must be set before the unit is start- CONFIGURATION HEADER AND DIP SWITCH ASSEM- ed in order for the unit to function properly. See Start Up, Po- BLY — The processor board is programmed to control a vari- tentiometers section on page 27 for information on establishing ety of air conditioning units. To tailor the processor to the par- set points. Each of the potentiometers has a valid range that is ticular unit being controlled, 2 devices are used. One is the used by the
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Table 3 — Output Pin and Terminal Assignments OUTPUT PIN- NAME RATING DEVICE TERMINAL Stage 1 J6-1 CR1 Compressor Relay (K1)* Stage 2 J6-2 U2** Compressor Relay (K2)* Stage 3 J6-3 U1 Compressor Relay (K3)* J6-4 Compressor Relay (K4)† Not Used 24 vac Stage 5 J6-5 CR2 Compressor Relay (K5)† Stage 6 J6-6 Not Used Compressor Relay (K6)† J6-7 Economizer Open Relay (K7) EOR J6-8 Economizer Close Relay (K8) ECR J5-1 Supply Fan Relay (K9) IFC J5-2 Morning Warm-Up Relay (K10) HIR Stage 1 Condenser J5-3 O
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P1 SUPPLY AIR TWO-DIGIT DISPLAY P3 — RESET LIMIT — The processor board is programmed SET POINT DISPLAY BUTTON for occupied space temperature reset. In order for reset to POTENTIMETER work, the accessory temperature reset board must be used. Potentiometer P3 is the maximum set point temperature to which the supply air can be reset. P5 — ECONOMIZER MINIMUM POSITION — This potentiometer controls the set point for the minimum position of the economizer. P6 — MORNING WARM-UP TEMPERATURE — This potent
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GAS SECTION HORIZONTAL SUPPLY SECTION (48FK,JK ONLY) (50FY,JY ONLY) AND EXTENDED PLENUM SECTION (50FKX,FKY,JKX,JKY) Fig. 7 — Thermistor T1 Location, 48FK,JK, 50FY,JY and 50FKX,FKY,JKX,JKY 034-048 Units FAN DISCHARGE/ELECTRIC HEAT SECTION Fig. 8 — Thermistor T1 Location, 50FK,JK034-048 Units 8
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GAS SECTION HORIZONTAL SUPPLY SECTION (50FS,FY,JY) (48FK,FM,JK) AND EXTENDED PLENUM SECTION (50FKX,FKY,FMX,FMY,JKX,JKY) Fig. 9 — Thermistor T1 Location, 48FK,FM,JK, 50JY and 50JKX,JKY 054-074 Units and 50FKX,FKY,FMX,FMY and 50FS,FY054-104 Units FAN DISCHARGE/ELECTRIC HEAT SECTION Fig. 10 — Thermistor T1 Location, 50FK,JK054-074 Units 9
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BAG STANDARD FILTERS FILTERS Fig. 11 — Thermistor T2 Location, Size 034-048 Units Fig. 13 — Thermistor T3 and T4 Locations, Size 034-048 Units ENTHALPY CONTROL 48FK,JK and 50FK,FY,JK,JY Units — Outside air enthalpy control is standard with the factory-installed economizer op- tion. Enthalpy is sensed by a controller located behind the end outside air hood. The control can be accessed by removing the upper hood filter. See Fig. 17. 48FM and 50FM,FS Units — The control is located on the metal upri
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054 UNITS 064, 074, 078 UNITS 088, 104 UNITS Fig. 14 — Thermistor T3 and T4 Locations, Size 054-104 Units 11
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The unit is supplied with a pressure transducer capable of measuring from 0.0 to 5.0 in. wg. The pressure transducer will send a 4 to 20 mA signal to the VFD to modulate the speed of the indoor fan motor to precisely control the fan to the desired static pressure set point. The VFD is factory set at 2.5 in. wg duct static pressure. Refer to the Operating Sequence section for more information on the VFD. The VFD has been programmed and wired at the factory for this application. No further adjustm
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A separate service manual for the factory installed PE VFD control box. When unit goes into Heating mode, interlock relay is supplied with each unit. Refer to PE VFD manual for more is energized providing switch closure or opening (depending information on the PE VFD. on how field power source is set up) to open the room termi- nals. Field connections for interlock relays are terminals 3 and Temperature Reset — Accessory temperature reset al- 4 (for normally open contacts) and terminals 3 and 7
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Fig. 20 — Unit Control Box Arrangement, Sizes 034-048 14
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15 Fig. 21 — Unit Control Box Arrangement, Sizes 054-078
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16 Fig. 22 — Unit Control Box Arrangement, Sizes 088 and 104
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034-048: TB3 034-048: TB3 OPERATING SEQUENCE — If space temperature is above 054-104: TB4 054-104: TB4 reset set point (T10 > P7), no reset will occur. If space temperature is equal to or less that reset set point 1 2 (T10 < P7), the LED will display 20 and reset will begin. Control will automatically adjust leaving air temperature by OCCUPIED/UNOCCUPIED the following formula: SWITCH MSP = SP + [(P3 - SP) / 3] x (P7 – T10) where: NIGHT SETBACK THERMOSTAT MSP = Modified Leaving-Air Set Poi
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RED RED BLK BLK SIZES 034-048 TB3 RED RED RED 12 BLK BLK BLK 15 TO ACCESSORY SPACE TEMPERATURE RESET CONTROL BOARD SIZES 054-104 TB4 12 15 SENSOR 1 SENSOR 2 SENSOR 3 SENSOR 4 SPACE TEMPERATURE RESET — 4 SENSOR AVERAGING APPLICATION SIZES 034-048 TB3 RED RED RED 12 BLK BLK BLK 15 TO ACCESSORY SPACE TEMPERATURE RESET CONTROL BOARD SENSOR 1 SENSOR 2 SENSOR 3 SIZES 054-104 TB4 12 RED RED 15 BLK BLK SENSOR 4 SENSOR 5 SENSOR 6 RED RED BLK BLK NOTE: Sensor part number is HH79NZ014. SENSOR 7 SENSOR 8 SE
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Connect the potentiometer end terminals to terminals 8 034-048: TB3 054-104: TB4 and 9 on control terminal block TB3 (sizes 034-048) or TB4 (sizes 054-104) (see Fig 27). Connect the switch terminals to 8 the potentiometer wiper arm terminal and to terminal 10 on TB3 or TB4. To enable demand limit function, change DIP switch 5 to position ON. (Disconnect control power before changing DIP 5-20K switch positions. Reconnect power after all changes have been 9 POTENTIOMETER (P4) made.) Set the pote
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OCCUPIED/UNOCCUPIED — The unit control system will Configuration — Configure as follows: initiate normal occupied mode functions (including Morning 1. Set DIP switch no. 2 to ON. Warm-up, Economizer Minimum Position, and Cooling Cycle) 2. Adjust manual potentiometer to 12.6 to 12.8 k-ohm. whenever a contact closure is made that emulates the normal 3. Configure transducer for job site input signal from BMS. timeclock contacts. See Fig. 23. (‘‘Occupied/Unoccupied Switch’’). The contact closure f
