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ACS Marvair Scholar 2.0 VDH Series Installation And Startup

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INSTALLATION AND
START-UP
Models VDH2024-2036-2040
& VAH2030-2048-2060
2 to 5 Ton Cooling Capacity with
2-Stage Compressors
SAFETY REQUIREMENTS
• If the information in these instructions are not
followed exactly, a fire may result causing
property damage, personal injury or loss of
life.
• Read all instructions carefully prior to
beginning the installation. Do not begin
installation if you do not understand any of
the instructions.
• Improper installation, adjustment, alteration,
service or maintenance can cause property
damage, personal injury or loss of life.
• Installation and service must be performed
by a qualified installer or service agency in
accordance with these instructions and in
compliance with all codes and requirements
of authorities having jurisdiction.
• Follow all safety codes.
MODEL NO.: ______________________ SERIAL NO.: _________________
DATE OF START-UP.: _______________
P.O. Box 400 • Cordele, Georgia 31010 • 156 Seedling Drive • Cordele, Georgia 31015
The most current version of this manual can be found at www.Marvair.com.
WARNING
Marvair, An AirX Climate Solutions Brand
(229) 273-3636 • Fax (229) 273-5154
VDH/VAH Heat Pumps &
VDH/VAH Air Conditioners
Manufactured By:
www.Marvair.com
1
Marvair VDH-VDH Scholar 2.0 I&S Manual 09/2024 New
Scholar 2.0
Marvair VDH-VDA Scholar 2.0 I&S Manual
09/2024 New

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Summary of Contents for ACS Marvair Scholar 2.0 VDH Series

  • Page 1 Scholar 2.0 VDH/VAH Heat Pumps & VDH/VAH Air Conditioners INSTALLATION AND START-UP Models VDH2024-2036-2040 & VAH2030-2048-2060 2 to 5 Ton Cooling Capacity with 2-Stage Compressors WARNING SAFETY REQUIREMENTS • If the information in these instructions are not followed exactly, a fire may result causing property damage, personal injury or loss of life.
  • Page 2 How To Use This Manual This manual is intended to be a guide to the Marvair VDH/VAH Scholar 2.0 line of vertical packaged heat ® pumps and air conditioners. This manual covers the installation and start-up of the Scholar 2.0 heat pumps and air conditioners, models VDH/VAH, with two stage compressors.

  • Page 3: Table Of Contents

    Failure to comply will result in death or severe personal injury and/or property damage. DANGER Failure to comply could result in death or severe personal injury and/or property damage. WARNING Failure to comply could result in minor personal injury and/or property damage. CAUTION Used to point out helpful info that will result in improved installation, reliability or IMPORTANT...
  • Page 4 Chapter 6: Scholar 2.0 Startup Start-Up Procedure ....................... 69 Chapter 7: Service and Charging/Recovery Safety Precautions ....................... 72 Leak Detection ......................72 Charging Procedures ....................73 Refrigerant Recovery ....................73 Chapter 8: Decommissioning Decommissioning ......................75 ILLUSTRATIONS Figure 1: General External Component Identification and Access to Scholar 2.0 Heat Pump or Air Conditioner ................

  • Page 5: Chapter 1: Description & Specifications

    Chapter 1: Description & Specifications GENERAL DESCRIPTION The Next Generation Scholar 2.0 VDH and VAH heat pumps and air conditioners from Marvair are modular HVAC systems designed to provide heating, cooling, and outside fresh air for school classrooms. The units are installed in the classroom against an exterior wall. The vertical configuration minimizes the floor space occupied by the HVAC unit.

  • Page 6: Model Identification

    MODEL IDENTIFICATION The identification numbering system for the Scholar 2.0 heat pump and air conditioner system is shown below. Example Position 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Unit Designation/Family V = Marvair Scholar Classroom Unit D = Dry Bulb Sensor E = Dry Bulb Sensor w/Dirty Filter A = 11 EER Indoor Air Quality...

  • Page 7: Bottom View

    44.13 [1120] 47.04 NOTE: SUPPLY [1195] 44” X 44” WALL SLEEVE IS AN EXAMPLE OF A COMMON SIZE. ACTUAL DIMENSIONS MAY VARY DEPENDING ON PROJECT SPECIFICATIONS. TOP VIEW 44.13 47.38 34.06 [1120] [1203] [865] 13.00 [330] 44.00 [1118] FRESH AIR FRESH AIR 95.63 [2429]...

  • Page 8: Top View

    32.75 TOP VIEW 48.07 1221 24” x 24” x 2” 24” x 24” x 2” Filter Filter 73.54 1868 INTAKE MOTOR LOCATED BEHIND THIS PANEL 2.08 22.09 2.08 RIGHT VIEW FRONT VIEW CONDENSATE DRAIN GREENCUBE (IF REQUESTED), Note: All overall outside dimensions are given with +/- .250”...

  • Page 9: Standard Controls

    STANDARD CONTROLS A. Programmable Logic Controller (PLC) Microprocessor Scholar 2.0 heat pumps and air conditioners use a factory installed PLC microprocessor to control the operation, the safety switches and function options. LED’s show operational status and provide assistance with diagnosis if troubleshooting is ever required. Various control functions are field selectable. The PLC is also capable of communicating to PLC’s in other Scholar units to allow run time leveling and does not require additional equipment installed in the Scholar 2.0...

  • Page 10: Thermostats And Sub-Bases

    factory to allow simultaneous operation upon a call for electric heat from the system thermostat. Electric heat will only operate: 1. Upon call from thermostat 2. When outdoor thermostat threshold is reached, if installed 3. Or during defrost when set to operate For non-simultaneous operation, navigate to “Option Selection”...

  • Page 11: Optional Controls

    4. MAR8000 thermostat. See Product Data Sheet for complete description.5. The direct digital control (DDC) interfaces with the building automation system (BAS) is to be defined by the specifier, in consultation with the Marvair ® sales representative. Marvair will factory install the DDC sent by the DDC manufacturer, and purchased by the customer. B.

  • Page 12: Chapter 2: Scholar 2.0 Installation

    Chapter 2: Scholar 2.0 Installation TOOLS/FIELD FURNISHED SUPPLIES WARNING TO AVOID PERSONAL INJURY, ADEQUATE PROTECTIVE CLOTHING MUST BE WORN AND PRECAUTIONS IN HANDLING AND INSTALLING THIS EQUIPMENT MUST BE PRACTICED AT ALL TIMES. • Power Drill/Driver & Extension • T25 TORX Bits •...

  • Page 13: Pre Checks

    WARNING DO NOT STACK THE UNIT OR ANY ACCESSORIES ON TOP OF ONE ANOTHER. THE UNITS SHOULD ALWAYS REMAIN IN THE UPRIGHT POSITION WHEN BEING SHIPPED, STORED, HANDLED OR INSTALLED. DO NOT STORE THE UNIT OR ACCESSORIES IN OUTDOOR WEATHER CONDITIONS. WARNING THE SCHOLAR 2.0 UNIT WEIGHS IN EXCESS OF 1,000 LBS.

  • Page 14: Location Selection And Preparation

    2.4 LOCATION SELECTION AND PREPARATION WARNING THE SCHOLAR 2.0 HEAT PUMP AND AIR CONDITIONER MUST BE INSTALLED IN CONFORMANCE WITH ALL APPLICABLE LOCAL AND NATIONAL ELECTRICAL, PLUMBING AND BUILDING CODES. A. The Scholar 2.0 heat pump and air conditioner must be installed on an outside wall for access to outside air.

  • Page 15: Power And Control Wiring (Rough-In)

    Scholar Heat Pumps VDH2024H VAH2030H VDH2036H VDH2040H VAH2048H VAH2060H Minimum Room Size (ft²) 157.1 166.9 196.4 196.4 206.2 216.0 Minimum Supply Height (ft) Scholar Air Conditioners VDH2024A VAH2030A VDH2036A VDH2040A VAH2048A VAH2060A Minimum Room Size (ft²) 157.1 166.9 196.4 196.4 206.2 216.0 Minimum Supply Height (ft)

  • Page 16: Wet Heat (Rough-In)

    WET HEAT (ROUGH-IN) A. Hot water coil connections are made by dropping supply and return lines through the knockout locations in the top of the plenums, as described in Figure 3 for the heat pump. Access to the interior cabinet is through these factory-notched locations. PREPARATION OF THE SCHOLAR 2.0 HEAT PUMP AND AIR CONDITIONER WARNING TO AVOID PERSONAL INJURY, ADEQUATE PROTECTIVE CLOTHING MUST BE WORN...
  • Page 17 90A and 90B. The duct system must be engineered to insure sufficient air flow through the unit to prevent over-heating of the heater element. This includes proper supply duct sizing, sufficient quantity of supply registers, adequate return and filter area. Ductwork must be of correct material and must be properly insulated. The duct work must be constructed of galvanized steel with a minimum thickness of .019. Ductwork must be firmly attached, secured and sealed to prevent air leakage. Do not use duct liner on inside of supply duct within four feet of the unit.

  • Page 18: Assembly/Disassembly Instructions

    ASSEMBLY/DISASSEMBLY INSTRUCTIONS WARNING THE SCHOLAR 2.0 UNIT WEIGHS IN EXCESS OF 1,000 LBS. WHEN MOVING THE UNIT, SUFFICIENT MANPOWER AND MECHANICAL EQUIPMENT MUST BE USED TO PREVENT DAMAGE TO THE UNIT AND INJURY TO PEOPLE. TO FACILITATE MOVING THE SCHOLAR 2.0, IT WILL BE NECESSARY TO ACCESS THE FORKLIFT AISLES AS SHOWN IN THIS SECTION OF THIS MANUAL.
  • Page 19 With a firm grip on the edge of the panel, slightly swing the panel away from the unit while you lift and pull the panel away from the guide flange. ALIGN THE THREE SCREWS HOLES AT THE TOP OF THE SIDE PANEL WITH THE THREE SCREW HOLES ON THE TOP PANEL AND SCREW IN PLACE D. Remove the screws securing the electrical panel covers. MATERIAL DRAWN 2020-10-02 TOLERANCES DRAWN BY This drawing contains confidential (EXCEPT AS NOTED)
  • Page 20 E. After removing the interior panel cover, disconnect the wiring to the blower assembly and the four wires to the transformer. Marvair VDH-VDA Scholar 2.0 I&S Manual 09/2024 New...
  • Page 21 F. Disconnect the condensate drain tube. G. Remove screws to separate upper and lower sections. Marvair VDH-VDA Scholar 2.0 I&S Manual 09/2024 New...
  • Page 22 H. Using a mechanical lifting device, separate upper and lower sections. I. After installation of the Scholar unit, install the duct flanges and side panel grommets. Scan this QR code to view a brief video demonstration of the Scholar unit separation procedure. Marvair VDH-VDA Scholar 2.0 I&S Manual 09/2024 New...

  • Page 23: Wall Sleeve Field Assembly Steps

    ITEM NO. PART NUMBER DESCRIPTION QTY. ITEM NO. PART NUMBER DESCRIPTION QTY. STEP 1: ASSEMBLE SNOUT SIDES TO SNOUT BOTTOM STEP 1: ASSEMBLE SNOUT SIDES TO SNOUT BOTTOM SMV15003X SNOUT BOTTOM SMV15003X SNOUT BOTTOM IMPORTANT SMV15007X SNOUT LH/RH SIDE SMV15007X SNOUT LH/RH SIDE STEP 2: ASSEMBLE SNOUT TOP TO SNOUT SIDES STEP 2: ASSEMBLE SNOUT TOP TO SNOUT SIDES...

  • Page 24: Installation Through The Outside Wall

    Item # Part # Description SMV15003X WALL SLEEVE BOTTOM SMV15007X WALL SLEEVE LH/RH SIDE SMV15013X 36” WALL SLEEVE BOTTOM SMV15016X CENTER WALL SLEEVE SIDES SMV45058X ODS BRACKET N/A (not shown) POP-IN WIRE TIE 0.5 INCH PLASTIC BUSHING.SLDASM THERMOCOUPLE SMV15030X SUPPLY AIR BLOCKOFF SMV15027X WALL SLEEVE DISCHARGE AIR UPPER DIVERTER SMV15026X...

  • Page 25: Condensate Float Switch Functional Check

    CAUTION WHEN FASTENING LOUVER/COLLAR ASSEMBLY TO AIR BOX, DO NOT OVER- TIGHTEN LOUVER SCREWS. OVERTIGHTENING SCREWS WILL CAUSE DAMAGE AND WARP THE LOUVER/COLLAR ASSEMBLY. TO PREVENT WATER FROM RUNNING DOWN THE INTERIOR OF THE WALL, INSTALL FLASHING UNDER THE OUTDOOR AIR BOX, OVER THE SILL OF THE WALL.

  • Page 26: Electrical, Condensate And Wet Heat Hook-Ups

    2.13 ELECTRICAL, CONDENSATE AND WET HEAT HOOK-UPS WARNING ALL ELECTRICAL, PLUMBING, AND REFRIGERATION WORK MUST MEET THE REQUIREMENTS OF LOCAL AND NATIONAL CODES AND ORDINANCES. WORK SHOULD BE DONE ONLY BY PROFESSIONALLY QUALIFIED AND TRAINED SERVICE PEOPLE. CAUTION NOTICE TO INSTALLER/CONTRACTORS: THIS UNIT’S INTERNAL CONTROL CIRCUIT/ TRANSFORMER IS DESIGNED TO POWER FACTORY INSTALLED UNIT COMPONENTS ONLY.

  • Page 27: Remote Thermostat Installation

    compressors since they will always start and run in the proper direction. However, three phase compressors will rotate in either direction depending upon phasing of power. Since there is a 50-50 chance of connecting power in such a way as to cause rotation in the reverse direction, it is imperative to confirm that the compressor is rotating in the proper direction at the initial field start-up of the system. Verification of proper rotation is made by observing that the suction pressure drops and the discharge pressure rises...

  • Page 28: Figure 6A: Remote Wall Mounted Thermostat Wiring Detail

    MARVAIR ® /SIMPLE COMFORT THERMOSTAT CONNECTION DIAGRAM FOR MARVAIR CLASSIC I™, CLASSIC II™ & SCHOLAR™ HEAT PUMPS THERMOSTAT PART NUMBER 50121/ SC2010-SL 50122/ SC2210-SL 50252/ SC4811-SL 50107/ SC5811-SL LOW VOLTAGE CLASSIC I & TERMINAL BOARD SCHOLAR W/O REHEAT CLASSIC II LOW VOLTAGE WITH TERMINAL BOARD...
  • Page 29 C. For Scholar 2.0 heat pump or air conditioner that interfaces with a building automation system (BAS) or energy management system (EMS), detailed instructions for the specific system being installed will be supplied separately by the manufacturer of the BAS/EMS system. The control of the GreenCube ERV and Ventilation relay (VR) are 24 volt inputs to the PLC.

  • Page 30: Figure 7: Ems Wiring Detail

    H. Wet heat hook-ups are done by connecting the rough-in piping to the factory supplied coils inside the plenum. ENERGY MANAGEMENT SYSTEM WIRING (EMS) For hot water heating, the plenum is equipped with a coil and a freeze protection INSTRUCTION TO TIE IN CUSTOMER EMS CONTROL thermostat embedded in the coil.

  • Page 31: Figure 8: Ventilation Controls Wiring Detail

    EMERGENCY VENTILATION SYSTEM INSTRUCTION FOR CUSTOMER VENTILATION CONTROL EMERGENCY VENTILATION SYSTEM CUSTOMER PROVIDED INSTRUCTION FOR CUSTOMER VENTILATION CONTROL CONTACT FOR EMERGENCY VENTILATION CONTROL CUSTOMER PROVIDED CONTACT FOR EMERGENCY VENTILATION CONTROL CUSTOMER PROVIDED WIRE CUSTOMER PROVIDED WIRE CONNECT 24V R CONNECT TO VENT TERMINAL BLOCK TERMINAL BLOCK 24V/...

  • Page 32: Figure 9B: Typical Control Center Layout For 3-Phase Scholar 2.0

    ITEM NO. PART NUMBER DESCRIPTION QTY. SMV16001X VDA CONTROL BOX MB03071-ADP BREAKER STAND, 208/230 03198 PLC DISPLAY 28 I/OS EHTERNET M172 MODBUS 15 AMP 3PH BREAKER 70888_A 50040 30AMP 3PHASE CONTACTOR 82015 TERMINAL STRIP VERNITRON W/8 LUG STAB GROUND LUG 91092 80812A TERMINAL STRIP VERNITRON A1 A2...

  • Page 33: Chapter 3: Scholar 2.0 Calibration, Controls & Hmi Operation

    Chapter 3: Scholar 2.0 Calibration, Controls & HMI Operation VENTILATION SYSTEM CALIBRATION Prior to start-up of the Scholar 2.0 heat pump or air conditioner, the ventilation system requires calibration to ensure the appropriate amount of fresh air is delivered to the classroom. Refer to the appropriate following ventilation system and use the instructions to calibrate the system for correct air delivery.

  • Page 34: Plc Control Adjustments

    Fresh Air Ventilation Points Test # Intake Vent Motor % Airflow Measure (CFM) Airflow Measurement (CFM) vs Intake Vent Motor Setting (%) C. GreenCube® ERV. Using best industry standards and practices, measure the fresh air that is being brought into the classroom. For units with one speed controller (std.), adjust the speed of the intake and exhaust blowers by inserting a slotted screw driver into the opening on the controller.

  • Page 35: Table 2: Led Function And Colors

    The keys can be programmed from the controller application. In the following table are described the keys default setting (keys are configurable through the logic controller. Each control can be adjusted by using the directional buttons. Note: In “Edit Mode”, the cursor flashes under the value that is going to be modified by the user. No. Key Press Once (press and release) • Scroll Up •...
  • Page 36 C. Adjusting Control Speed Parameters Use the right or left arrow key to navigate to the “Control Speed Settings” screen. STEP 1. Use the Up/ Down arrow key to make your selection. STEP 2. Press “OK” key to enter, then use the Up/ Down key to change first the value. STEP 3. Then use the Left/ Right key to go to the next value. STEP 4.
  • Page 37 E. Adjusting Exhaust Motor Timer The exhaust motor timer is to adjust the time it takes to Vent (ventilation) output to energized which will then send 24VAC to the exhaust motor relay coil. The default time is 2 seconds, which can be changed from 2, 5 and 10 seconds. Note: Because the times are preset values, the time cannot be manually changed to a undefined value.
  • Page 38 The PLC inputs are powered only by 24 VAC. The thermostat inputs are: • G - Blower signal from thermostat • Y - Compressor • W2 - Second stage heat (heat pump function only) • O - Reversing valve (energized for cooling) (heat pump function only) •...
  • Page 39 H. PLC Outputs An output is a signal from the PLC to the Scholar 2.0 heat pump or air conditioner or thermostat. All digital outputs on the PLC are 24V. These outputs are: • OAM - Outdoor Air Motor (Fresh air motor for the GreenCube ERV) •...
  • Page 40 full capacity display “on” on the PLC HMI output screen. The Indoor Blower Motor (IBM) and Outdoor Fan Motor (OFM) output speed will display the percentage value for their current speed on the PLC HMI output screen. The Output indicate that the PLC is sending a signal to the devices’ controls. If the thermostat calls for second stage heating (heat pump only), the W2 Input will be on and the HC Output will be on.
  • Page 41 When the system has been operating in the heat pump mode for a period of time (set by the Defrost Timer), the system will examine the Defrost Control thermostat Input (DFC). If this input is on (the thermostat is closed), indicated by Output being on, the system will go into Defrost mode based on the defrost time default = 30min (30, 60 &...
  • Page 42 N. OFM Head Pressure Control Modulating Head Pressure Control (ECM Outdoor Motors) – A10K Nominal NTC sensor is secured to the liquid line of the system to monitor the liquid line temperature and is connected to analog input 8 (AI.8). The thermistor value is used as the process variable when controlling the head pressure.
  • Page 43 O. Economizer And Ventilation Control Scholar 2.0 are 2 stage units and Scholars with PLC and economizer option installed should use a 2 stage thermostat, to bring on Y2. If outside conditions are favorable the economizer will run to utilize “free” cooling. If the outside conditions are not favorable 1st stage mechanical cooling will operate.
  • Page 44 P. Outdoor Sensor Type • NTC Sensor used for Dry bulb only • Temp/Hum 4 wire sensor used for Enthalpy sensor only Q. Defrost Timer (DFT) (heat pump function only) Located on the “Preset Timer” screen. The defrost control is based upon both time and temperature.
  • Page 45 T. Troubleshooting The PLC is a microprocessor-based system that has the ability to provide a great amount of information to aid in troubleshooting a malfunctioning system. With the Input and Output screen user can easily diagnose most problem by just seeing what is on and or what is off.
  • Page 46 1. Outdoor Thermostat (heat pump only). Factory set at 40°F, this thermostat determines the outdoor temperature at which the supplemental electric heat or wet heat turns on. This may be field adjusted to the desired temperature setting by changing the settings on the PLC option selection screen. Marvair VDH-VDA Scholar 2.0 I&S Manual 09/2024 New...

  • Page 47: Chapter 4: Scholar 2.0 Networking And Remote Communication

    Chapter 4: Scholar 2.0 Networking and Remote Communication BACNET INFORMATION This section serves as a reference for the BACnet Information on the VDH units. Below are all the Analog and Boolean points that are Read/ Write and Read only. BACnet device ID & IP address can be configured over BACnet network or locally on the PLC screen to address multiply units over BACnet network.

  • Page 48: Ethernet Port

    3. Architecture Wiring Examples. The following diagram shows an RS-485 (field) architecture wiring example: 4. Communication Settings. Modbus/BACnet ID, PLC address and RS-485 port 1 and port 2 settings. 4.3 ETHERNET PORT 1. Overview. Each TM172P••••• controller is equipped by an RJ45 Ethernet port. To access the RS485-1 and RS485-2 screen, press and hold the right arrow key then press the right arrow key again for the next screen.
  • Page 49 Main Web functionalities: • Web-based access. • Remote reading and support. • Local and remote system control, including alarms management. • Preventive and predictive maintenance. • Email alarm alerts. Care must be taken and provisions made for use of this product as a control device to avoid inadvertent consequences of commanded machine operation, controller state changes, or alteration of data memory or machine operating parameters.
  • Page 50 Status LED. RJ45 Ethernet Status LED Label Signal Color Status Description No Link Ethernet Link Green/Yellow Yellow On Link at 10Mb Green On Link at 100Mb No Activity Ethernet Activity Green Flashing Activity Operation Guide Scan this QR Code for the full PLC Operation Guide Marvair VDH-VDA Scholar 2.0 I&S Manual 09/2024 New...

  • Page 51: Chapter 5 Optional Electronic Control Board

    Chapter 5 Optional Electronic Control Board Introduction WARNING FAILURE TO OBSERVE THE INSTRUCTIONS CONTAINED IN THIS DOCUMENT MAY RESULT IN PERSONAL INJURY AND/OR PROPERTY DAMAGE AND MAY VOID THE WARRANTY. READ THIS MANUAL BEFORE INSTALLING, REPLACING OR USING THIS PRODUCT. Marvair’s proprietary Printed Circuit Board (PCB) sets the standard for the industry in flexibility, reliability and performance.

  • Page 52: Installation And Replacement

    I/O Table for Control Board Item Description Economizer Actuator Output 2-10 VDC Outdoor Motor Control Output 0-10 VDC or PWM Indoor Motor Control Output 0-10 VDC or PWM Enthalpy Sensor Signal Input 4-20mA Outdoor Sensor Signal 10K NTC (Heat Pumps) / Dry Bulb Sensor Signal Input 10K NTC (Systems Equipped with Dry Bulb Economizer) Supply Air Sensor Signal Input 10K NTC (Systems Equipped with Economizer) Defrost Sensor Signal Input 10k NTC (Heat Pumps Only)
  • Page 53 5.3.1 – Programming Menu Configuration 1. To Enter Programming Mode: • Press and hold the Menu button for 5 seconds until P-01 is displayed. 2. While in Programming Mode main menu: • Press the Menu button to enter the displayed parameter menu. •...
  • Page 54 Configuration Menu Details 1. AC/HP Select: This setting allows the PCB to be configured for AC (air-conditioner) or HP (heat-pump). The system type is configured at the factory during production testing for the appropriate system type. The default system type is AC. 2. IBM Select: This setting allows the IBM (Indoor Blower) control signal to be configured for PWM or 0-10vdc control. The default control output signal is PWM. 3. Fan Purge: This setting allows the delay off time of the indoor blower once the call for the indoor blower has been removed.
  • Page 55 in heat-pump mode upon a call for W2 (auxiliary / emergency heat). When the SCKT Set is set to Y (yes) the electric heat will not be allowed to operate with the compressor in the heat-pump mode. When set to Y (yes) and upon a request for W2 (auxiliary / emergency heat) the compressor will shut off and the electric heat will operate.

  • Page 56: Operation

    The default setting for the Dehum speed is 80% of maximum speed. The speed may be adjusted from 60-100% in 1% increments to meet desired airflow requirements. 18. Pulse Reheat: This setting allows the dehumidification output “RH” to be cycled On and OFF based on the Dehum Supply temperature setpoint. The Options are Y= Yes or N= No and the default is Y. 19.

  • Page 57: Sequence Of Operation

    Sequence of Operation IMPORTANT All equipment should go through the recommended commissioning/start up sequence to ensure safety and system reliability. This document is only valid if the system is used as intended. This section defines the manner and method of control of the HVAC system. It will cover the following operations and protections. 1.0 Indoor Blower Operation G - Indoor Blower Only Y1 - Indoor Blower Operation Y2 - Indoor Blower Operation...
  • Page 58 Note: Equipment, devices and necessary system components are specified in the respective section. Note: 1. All inputs on the control board go through a 5 seconds Time-On Delay to prevent nuisance request. Compressor Outputs go through 5 seconds staggered Time On delay to prevent nuisance tripping of breaker due to the inrush associated with these large inductive loads. 2.
  • Page 59 2.0 Cooling Operation AC Systems Request Active Input Active Output Stage 1 Cooling (Fixed Compressor) CC1 (Partial Capacity) Stage 1 Cooling (2 Fixed Compres-sors) Y1 or Y2 CC1 or CC2 Respectively (Partial Capacity) Stage 1 Cooling (1 Staged Compressor) CC1 (Partial Capacity) Stage 2 Cooling (2 Fixed Compres-sors) Y1 + Y2 CC1 + CC2 (Full Capacity)
  • Page 60 2.2 Mechanical Cooling (HP systems) – This section will describe the sequence of operation which takes place during Direct Expansion (DX) cooling from a control standpoint. The reversing valve (O Input) must be energized for Cooling operation on Heat Pump systems. Note: The system type must be configured for “HP” operation in setting 1 of the configuration menu of the control board for proper HP system operation. This system type is selected at the factory and there’s no need to change this setting.

  • Page 61: Figure 12: Enthalpy Sensor And Temperature Control Points

    blade. It is capable of driving a full 90 degrees within 90 seconds. The assembly has a spring return to close the damper during power outage. 3.1 Enthalpy Sensor and Operation – The enthalpy sensor responds to the total heat content of the outdoor air to provide the changeover to outside air for free cooling.

  • Page 62: Figure 13: Dry Bulb Sensor

    During the testing of the air conditioner at the factory, the control board has been configured for the sensor type used in the system. There should be no need to change the sensor configuration. If an enthalpy sensor is being used, setting 13 of the control board configuration menu will be set for EN= Enthalpy. A disconnected or faulty enthalpy sensor is annunciated on the control board display as “ES-F”. Economizer operation is only allowed in Cooling Mode. Note: A call for Y2 or FC Inputs or a faulty or disconnected enthalpy sensor will override the economizer operation and force the compressor to operate.
  • Page 63 3.4 Minimum Position – The minimum position controls the amount of outside air introduced in the building when not in economizer operation or to meet a minimum outside air requirement to keep the damper open. This feature is only applicable to systems with economizer or ventilation damper options.
  • Page 64 temperature of 70°F or higher before the 10-minute maximum run time, the defrost cycle will terminate. If the defrost cycle has not completed (DS sensor above 70F) due the heating call being satisfied, the defrost cycle will continue upon the next call for heat pump heating to complete the defrost cycle. If freezing conditions are not present at the end of the defrost interval timer, the system will not perform a defrost cycle.
  • Page 65 EHDD – Electric Heat During Defrost (Heat-Pumps Only) The EHDD is a selectable menu option in the control board configuration menu setting 9. The options for this feature are Y=Yes or N=No. When set to Y=Yes, control board will force the electric heat to operate during a defrost cycle unless SCKT is set to Y=Yes or the outdoor temperature is not below ODS (if equipped) setpoint.
  • Page 66 Note: A request for Y1 or Y2 vis digital input or Modbus takes priority over dehumidification operation and the electric heat will de-energize. 5.3 Pulse Reheat / Dehum Supply Set – The Pulse reheat feature allows for supply air temperature limiting dehumidification control. When setting 18 is set to Y in the configuration menu the RH output of the control board will energize and de- energized based on the dehumidification supply air temperature setpoint in setting 19 of the configuration menu. During dehumidification operation the RH output...
  • Page 67 the current fault. The fault for a low-pressure lockout will displayed as “LP-1” or “LP-2” followed by “F”. The faults can also be monitored via Modbus by reading the respective value based on the Modbus map that is provided. After this lockout condition is reached, the cooling/heat pump heating call must be cycled (on/off of respective request) or the system must be power cycled to clear the fault.
  • Page 68 7.2 Emergency Ventilation (Motorized Damper or Economizer Equipped Systems) – When there is a request for “Emergency Ventilation” (EV-signal via Digital input or Modbus), the system will run the Indoor Motor at the “Y2” speed setting on the board or via Modbus and provide a 10vdc signal from the ECO output of the control board to drive the motorized damper fully open.

  • Page 69: Chapter 6: Scholar 2.0 Startup

    Chapter 6: Scholar 2.0 Startup 6.1 START-UP PROCEDURE CAUTION THIS UNIT CONTAINS A CRANKCASE HEATER (CCH). FAILURE TO FOLLOW INSTRUCTIONS REGARDING THE CCH AND STARTUP WILL VOID THE MANUFACTURER’S WARRANTY. Note for Scholar 2.0 units manufactured after 12/05/2022: Crankcase heaters (CCH) help to prevent refrigerant migration in the off cycle of the compressor, which prevents oil dilution in the compressor.

  • Page 70: Table 3: Voltage Limitations

    2. Set the remote thermostat system switch to “OFF” position. The blower switch should be in “AUTO” position. 3. Check the voltage supply to the disconnect. If voltage readings are appropriate, proceed with start-up. (See Figure 13 for acceptable voltage ranges.) If voltage readings are not appropriate, check the power leads at the disconnect and the main breaker in the mechanical room.
  • Page 71 8. Automatic Changeover For an automatic changeover remote thermostat, the proper functioning of the system can be checked for cooling and heating by using the same sequence as detailed above with the thermostat system switch put in “AUTO” position. 9. Emergency Heat (heat pump version only) This setting on a remote thermostat is to provide electric heat in the event the compressor does not function, and heat is required.

  • Page 72: Chapter 7: Service And Charging/Recovery

    Chapter 7: Service and Charging/Recovery 7.1 SAFETY PRECAUTIONS SERVICE Prior to beginning work on systems containing FLAMMABLE REFRIGERANTS, safety checks are necessary to ensure that the risk of ignition is minimized. For repair to the REFRIGERATING SYSTEM, the following shall be completed prior to conducting work on the system.

  • Page 73: Charging Procedures

    If a leak is suspected, all naked flames shall be removed/extinguished. If a leakage of refrigerant is found which requires brazing, all of the refrigerant shall be recovered from the system, or isolated (by means of shut off valves) in a part of the system remote from the leak. 7.3 CHARGING PROCEDURES In addition to conventional charging procedures, the following requirements shall be followed.
  • Page 74 6. For appliances containing flammable refrigerants, refrigerants purging shall be achieved by breaking the vacuum in the system with oxygen-free nitrogen and continuing to fill until the working pressure is achieved, then venting to atmosphere, and finally pulling down to a vacuum (optional for A2L). This process shall be repeated until no refrigerant is within the system (optional for A2L). When the final oxygen-free nitrogen charge is used, the system shall be vented down to atmospheric pressure to enable work to take place 7.

  • Page 75: Chapter 8: Decommissioning

    Chapter 8: Decommissioning 8.1 DECOMMISSIONING Before carrying out this procedure, it is essential that the technician is completely familiar with the equipment and all its details. It is recommended good practice that all refrigerants are recovered safely. Prior to the task being carried out, an oil and refrigerant sample shall be taken in case analysis is required prior to re-use of recovered refrigerant.

  • Page 76: Appendix A - Wiring Diagrams

    APPENDIX A - WIRING DIAGRAMS Fig 1. Typical Wiring Schematic for 2T-5T A/C | 230V 1-Phase w/PLC Marvair Scholar 2.0 I&S Manual 05/2024 Rev.9...
  • Page 77 Fig 2. Typical Wiring Schematic for A/C | 230V 3-Ph Power w/PLC Marvair Scholar 2.0 I&S Manual 05/2024 Rev.9...
  • Page 78 Fig 3. Typical Wiring Schematic for A/C | 460V 3-Phase w/PLC Marvair Scholar 2.0 I&S Manual 05/2024 Rev.9...
  • Page 79 Fig 4. Typical Wiring Schematic for HP | 230V 1-Phase w/PLC Marvair Scholar 2.0 I&S Manual 05/2024 Rev.9...
  • Page 80 Fig 5. Typical Wiring Schematic for HP | 230V 3-Phase w/PLC Marvair Scholar 2.0 I&S Manual 05/2024 Rev.9...
  • Page 81 Fig 6. Typical Wiring Schematic for HP | 460V 3-Phase w/PLC Marvair Scholar 2.0 I&S Manual 05/2024 Rev.9...
  • Page 82 Fig 7. Typical Wiring Schematic for 2T-5T A/C | 240V 1-Phase w/PCB Marvair Scholar 2.0 I&S Manual 05/2024 Rev.9...
  • Page 83 Fig 8. Typical Wiring Schematic for 2T-5T A/C | 240V 3-Phase w/PCB Marvair Scholar 2.0 I&S Manual 05/2024 Rev.9...
  • Page 84 Fig 9. Typical Wiring Schematic for 2T-5T A/C | 460V 3-Phase w/PCB Marvair Scholar 2.0 I&S Manual 05/2024 Rev.9...
  • Page 85 Fig 10. Typical Wiring Schematic for 2T-5T Heat Pump | 240V 1-Phase w/PCB Marvair Scholar 2.0 I&S Manual 05/2024 Rev.9...
  • Page 86 Fig 11. Typical Wiring Schematic for 2T-5T Heat Pump | 240V 3-Phase w/PCB Marvair Scholar 2.0 I&S Manual 05/2024 Rev.9...
  • Page 87 Fig 12. Typical Wiring Schematic for 2T-5T Heat Pump | 460V 3-Phase w/PCB Marvair Scholar 2.0 I&S Manual 05/2024 Rev.9...

  • Page 88: Appendix B - Ratings And Data

    APPENDIX B - RATINGS AND DATA 1.01 RATINGS / DATA AIR FLOW CFM ESP (WET COIL) BASIC MODEL 0.10 0.15 0.20 0.30 0.40 0.50 VDH2024 ––– ––– VDH2036 1380 1340 1290 1200 ––– ––– VDH2040 1380 1340 1290 1200 ––– –––...

  • Page 89: Appendix C - Base Stand Installation

    APPENDIX C - BASE STAND INSTALLATION 1.01 TOOLS/FIELD FURNISHED SUPPLIES WARNING TO AVOID PERSONAL INJURY, ADEQUATE PROTECTIVE CLOTHING MUST BE WORN AND PRECAUTIONS IN HANDLING AND INSTALLING THIS EQUIPMENT MUST BE PRACTICED AT ALL TIMES. • Power Drill/Driver and Extension •...

  • Page 90: Installation

    HOLES TO SECURE BASE STAND TO FLOOR HOLES TO SECURE SCHOLAR 2.0 STAND TO BASE STAND Figure 1. Top View of Base Stand Also, recheck the locations of the electrical and condensate stub-outs to ensure they are located properly, relative to the cabinet knock-out openings as shown in the Installation and Start-Up Manual, Figures 3 and 4.
  • Page 91 WARNING WHEN MOVING/RAISING THE SCHOLAR 2.0 CABINET, UTILIZE ADEQUATE RESOURCES TO HANDLE THE 1,100 LB. CABINET. THIS IS TO AVOID PERSONAL INJURY OR DAMAGE TO THE EQUIPMENT/FACILITIES. With appropriate resources to lift the Scholar 2.0 unit, place it on the base stand while guiding the air box through the wall opening and maintaining clearance between the plenum (as appropriate) and the ceiling.

  • Page 92: Appendix D - Installation Of The Freeblow Plenum

    APPENDIX D - INSTALLATION OF THE FREEBLOW PLENUM 1.01 TOOLS/FIELD FURNISHED SUPPLIES WARNING TO AVOID PERSONAL INJURY, ADEQUATE PROTECTIVE CLOTHING MUST BE WORN AND PRECAUTIONS IN HANDLING AND INSTALLING THIS EQUIPMENT MUST BE PRACTICED AT ALL TIMES. • Power Drill/Driver and Extension •...

  • Page 93: Plenum Installation

    1.03 PLENUM INSTALLATION 1. Prior to mounting the plenum on top of the Scholar 2.0 unit, remove the front panel from the plenum. Retain the screws (red arrows) for reinstallation after the plenum has been installed. 2. On the top panel of the Scholar 2.0 unit, locate the 6 holes that correspond with the six mounting holes in the plenum.
  • Page 94 The air distribution system which is field supplied and installed downstream of the specified ducted plenum must be engineered to assure sufficient air flow, even under adverse conditions, such as dirty filters. The information provided in Figure 1, Appendix A should be used to design the air distribution system duct size leaving the Scholar 2.0 unit, keeping the external static pressure to a minimum. Applications using duct work should be designed and installed in accordance with the current edition of the National Fire Protection Association codes and standards 90A and 90B. The duct system must be engineered to insure sufficient air flow through the unit to prevent over-heating of the heater element.

  • Page 95: Appendix E - Trim Strip Installation

    APPENDIX E - TRIM STRIP INSTALLATION 1.01 TOOLS/FIELD FURNISHED SUPPLIES WARNING TO AVOID PERSONAL INJURY, ADEQUATE PROTECTIVE CLOTHING MUST BE WORN AND PRECAUTIONS IN HANDLING AND INSTALLING THIS EQUIPMENT MUST BE PRACTICED AT ALL TIMES. • Power Drill/Driver and Extension •...

  • Page 96: Appendix F - Outdoor Louver/Collar Installation

    APPENDIX F - OUTDOOR LOUVER/COLLAR INSTALLATION 1.01 TOOLS/FIELD FURNISHED SUPPLIES WARNING TO AVOID PERSONAL INJURY, ADEQUATE PROTECTIVE CLOTHING MUST BE WORN AND PRECAUTIONS IN HANDLING AND INSTALLING THIS EQUIPMENT MUST BE PRACTICED AT ALL TIMES. • Power Drill/Driver and Extension •...
  • Page 97 The Scholar 2.0 heat pump or air conditioner should be installed following the instructions in this manual. After installation, the Scholar 2.0 air box should be from 1-1/4” to 1-3/8” from the outside surface of the finished wall, as shown in Figure 1. FREEBLOW PLENUM DISTANCE (INCHES) BETWEEN AIR BOX AND OUTSIDE FINISHED WALL LOUVER/COLLAR SCHOLAR V™...
  • Page 98 IMPORTANT BE SURE AIR BOX IS PLACED 1-3/8” TO 1-1/2” INSET FROM OUTSIDE WALL SURFACE. USE LOUVER/COLLAR SCREWS THAT ARE COMPATIBLE WITH THE COLOR OF THE COLLAR. NOTES: 1. The louvers come in three different configurations depending on mounting requirements: (#1) is the louver with collar, (#2) is the louvered grille without collar and (#3) is the collars.

  • Page 99: Appendix G - Startup & Commissioning Checklist

    APPENDIX G - STARTUP & COMMISSIONING CHECKLIST Please complete the information on this form and email to MarvairCustServ@airxcs.com. Date: _____/_____/_______ A. Owner & Location Equipment Owner: _________________________________________________________ Address: _________________________________________________________ City: _________________________________________________________ State: _______ , Zip: ___________ B. Installing Contractor Company: ________________________ Installer: _________________________ Address: ________________________________________________________ City: ________________________________________________________ State: _______ , Zip: ___________...

  • Page 100: Starting Unit

    E. Check Incoming Power at Terminal Block and verify Proper Voltage and Balance BEFORE STARTING UNIT. ❒ 208/230V 1 Phase 60 Hz. ❒ 208/230V 3 Phase 60 Hz. ❒ 460V 3 Phase 60 Hz. ❒ 380V 3 Phase 50Hz. ❒ 575 3 Phase 60 Hz. ❒...
  • Page 101 F. Cooling Mode (Mechanical Cooling) Close the Compressor (Cooling) circuit breaker. Power will be applied to the thermostat / control device. Setup / Configure the control for the desired settings. Adjust the cooling setpoint so there is No demand for cooling. The unit will not be running. Cooling Start If using a standard thermostat, Set the Control to ON, Mode to Cooling, Fan to Auto (other con- trols, set appropriately for cooling mode).
  • Page 102 Cooling (Check and Record Readings) After about 10 minutes of operating in the cooling mode, check and record the following data points. Inside Temperature (IAT) ºF Outside Temperature (OAT) ºF Entering Condenser Air Temperature (Should be same temp as OAT) ºF Leaving Condenser Air Temperature (Acceptable Range 15º...
  • Page 103 Electric Reheat Re-Start While the system is still operating in “Cooling Mode” from the previous test. Re-Start Dehumidification. Do Not change the Humidity Setpoint on the Humidistat. Simply adjust the cooling setpoint to approximately four degrees above the current indoor temperature. After the short delay, the unit will sequence on, start dehumidification. Notice: system did not turn off. The Only change that occurred is “Heater turned on”.
  • Page 104 Economizer Cooling Stop Adjust the cooling setpoint to approximately two degrees above the current indoor temperature. The unit will sequence off.  Is the Economizer Damper Closed? ................ ❒Yes ❒No  Is the indoor blower motor (IBM) Off? ..............❒Yes ❒No Heating Mode (Mechanical Heating Heat Pump) Close the Compressor (Cooling) circuit breaker.
  • Page 105 Auxiliary Heat (ODT) While the system is operating in “Mechanical Heating Mode”. Activate Auxiliary Heat (ODT). * Your unit may be configured with an outdoor thermostat configured as “Auxiliary Heat” or “Mechanical Heat Lockout”, or No outdoor thermostat. * Do Not change the temperature setpoint on the thermostat / control. Simply adjust the ODT set- point to approximately four degrees below the current outdoor temperature.
  • Page 106 Calculate Heater kW Single Phase Units Heater kW = (HCAL1*L1&L2)/1000 = _______________kW. Example: HCAL1 * L1&L2 1000 Measured Voltage: L1&L2 = 241 Volts Measured Amperage: L1 = 20.7 Amps 4988.7 / 1000 = 4.99kW (5kW) Three Phase Units Heater kW = (HCAL1*L1&L2) + (HCAL2*L1&L3) + (HCAL3*L2&L3)/1000 = __________kW. Example: (HCAL1*L1&L2) + (HCAL2*L1&L3) + (HCAL3*L2&L3) 1000 Measured Voltage: L1&L2 = 241 Volts...

  • Page 107: Appendix H: Electronic Control Board Modbus Map

    Appendix H: Electronic Control Board Modbus Map Default Modbus RTU Settings Slave ID Baud = 19200 Data Bits = 8 Stop Bits = 1 Parity = None First Coil 1 , No. of Coils 30 RJ11 Pinout for Communication Discrete Bit/Bool: Read with Function Code 02 multi discrete input read, Write to RW coil with Function Code 05 Single Coil write.
  • Page 108 Registers: Read with Function Code 04 Multi register reads, Write to RW register with Function Code 06 write single register. Attempted Writes to RO registers result in error return. Func 0x10 multiple register writes not supported. MODBUS Human OBI PACKET Register ID REGISTER ZeroBase...
  • Page 109 40020 Current Status of MIN POS 16 bit 20 = MIN, 20-100= OPEN % 40021 Economizer Dry Bulb Temperature setpoint 16 bit 70F=default, 20F-105F 40022 ODS set 16 bit 50 default, 0-70 N= 0, 10-90 SECONDS, 40023 Fan Purge 16 bit 90 SEC IS DEFAULT 40024 Defrost Timer...

This manual is also suitable for:

Marvair scholar 2.0 vah seriesMarvair scholar 2.0 vdh2024-2036-2040Marvair scholar 2.0 vah2030-2048-2060

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