Airxcel Marvair VAIVA36 Maintenance And Service Manual Download Page 25

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Scholar V VAIVA Maintenance & Service Manual 10/2017 Rev.2

Demand Control Ventilation

A field or factory installed carbon dioxide sensor controls the ventilation damper and

only opens the damper when CO

levels exceed a specified level. Demand control

ventilation saves energy and utility costs by ventilating the classroom based upon

occupancy.

Note:

Not available on manual fresh air damper (“B”) configuration.

Outdoor Temperature Sensor

This sensor determines the outdoor temperature at which the supplemental electric

heat turns on and is user adjustable. This may be field adjusted to the desired

temperature setting in the PLC. Please note that when the outdoor sensor activates

wet heat, the compressor does not operate.

The outdoor thermostat is located in the inlet to the condenser coil.

Outside air

temperature information

is used to switch heat pump off and electric resistance on if

outdoor air gets too cold for satisfactory heat pump heating.

OUTDOOR TEMPERATURE

SENSOR

Figure 11. Outdoor Temperature Sensor

Summary of Contents for Marvair VAIVA36

Page 1: ...V with Free Blow Plenum WARNING SAFETY REQUIREMENTS If the information in these instructions is not followed exactly a fire may result causing property damage personal injury or loss of life Read all...

Page 2: ...these rules may result in death serious bodily harm property damage and damage to the equipment Important SafetyPrecautions 1 USE CARE when LIFTING or TRANSPORTING equipment 2 TRANSPORT the UNIT UPRIG...

Page 3: ...or property damage IMPORTANT Used to point out helpful suggestions that will result in improved installation reliability or operation HEATING VENTILATING AND AIR CONDITIONING EQUIPMENT MAINTENANCE SER...

Page 4: ...ned outside air is being introduced into the classroom The GreenWheel and GreenCube ERV dehumidify and cool the outside air in the summer They humidify and heat the outside air during the winter Tempe...

Page 5: ...vered to the classroom Refer to the appropriate following ventilation system and use the instructions to calibrate the system for correct air delivery A Manual Fresh Air System Fresh air ventilation b...

Page 6: ...one blower motor speed controller The blower speed controller operates both blowers in tandem An optional blower speed control for the exhaust air blower can be factory installed to provide independe...

Page 7: ...and PowerVent System Calibration Procedure C GreenWheel and GreenCube ERV Using best industry standards and practices observe that fresh air is being brought into the classroom For units with one spe...

Page 8: ...ater or a mild detergent Do not use bleach abrasive chemicals or harmful solvents C If the Indoor Coils becomes clogged or dirty it may be cleaned by careful vacuuming or with a Marvair approved evapo...

Page 9: ...otor speed is controlled by a PLC and will modulate with the compressor C Outdoor Air Mover The outdoor air mover is an axial fan with an asynchronous external rotor motor on the 2 and 3 ton heat pump...

Page 10: ...Charge Heat Pump Switches Optional Heat Pump Only Indoor Coil Freeze Stat These switches render the compressor and outdoor fan motor inoperative whenever the limits of the high or low pressure switche...

Page 11: ...wing the heat pump to switch from cooling to heating or heating to cooling I Exhaust Air Ventilation Blower is used to exhaust classroom in the GreenWheel ERV and Power Vent ventilation options The bl...

Page 12: ...itch is a line current one time limit switch If it senses an excessive temperature power is turned off to the elements This switch does NOT reset when the temperature drops and must be replaced if it...

Page 13: ...rsing Valve Reheat Valve Outdoor Fan 1 Resistance Heat Contactor Outdoor Fan 2 Indoor Blower Enable Ventilation 500 ohm resistor Figure 6 Scholoar V PLC A Digital Inputs All digital inputs are powered...

Page 14: ...rol Relay C Analog Inputs AI 0 0 10 VDC modulating signal from indoor Relative Humidity Transmitter 0 Volts 0 RH 10 volts 100 RH AI 1 2 10 VDC modulating signal from indoor Temperature Transmitter 2 V...

Page 15: ...00 rpm in cooling and 4800 rpm in heating Cooling or heating capacity is basically proportional to the compressor speed All limits are programmable A control band is established by assigning a differe...

Page 16: ...increases incrementally by 4 volts every 20 seconds adjustable to a maximum of 9 volts Figure 7 Scholar V Cooling Control Method Deadband Setpoint Below the lower point of the deadband the compressor...

Page 17: ...r Temperature and Relative Humidity set point adjustments are made on the HMI Human Machine Interface screen typically located on the front of the unit The HMI contains several screens with parameters...

Page 18: ...ling Auto H C Press this button one time to have the unit automatically switch between cooling and heating If the room gets above the cooling set point space cooling will be operated If the room gets...

Page 19: ...l load caused by fresh air Emergency Heat In this mode all compressor functions are disabled and heating is provided with electric resistance heating elements Emergency Heat In this mode all compresso...

Page 20: ...Supply Air This is the real time temperature of the air coming out of the unit Outside Air This is the real time temperature of the ambient outside air Outside Coil 1 This is the temperature read by...

Page 21: ...smitted by the RH transmitter located in the inlet to the evaporator coil Forward Press this button to go forward one screen Back Press this button to go back one screen Back to Main Press this button...

Page 22: ...user adjustable relative humidity the unit runs to try to achieve in the Cooling Mode or in the Dehumidification with Reheat mode The Dehumidification with Reheat mode will automatically come on if th...

Page 23: ...vice Manual 10 2017 Rev 2 D Other Screens There are several other screens used for diagnostics The screens are shown below but detailed discussion is not provided in this document See Appendix A for d...

Page 24: ...mpressor will start and operate for 60 seconds even with the LPS switch open three times before causing a lockout on low pressure This interval is adjustable requires user login High Pressure Switch T...

Page 25: ...n Outdoor Temperature Sensor This sensor determines the outdoor temperature at which the supplemental electric heat turns on and is user adjustable This may be field adjusted to the desired temperatur...

Page 26: ...Rely only on the internal program of the unit for mode function In diagnosing common faults in the Scholar V system develop a logical thought pattern as used by experienced technicians The charts and...

Page 27: ...ures pressure at outlet of evaporator Sends pressure value to EEV controller for superheat calcu lation 21 Check Valve allows condensed refrigerant to bypass EEV during heating mode 22 Indoor Distribu...

Page 28: ...BK 77 Y 64 BL 74 Y 70 RD 61 BL 62 BK 4 BK 14 GR 44 Y 45 BL 46 RD 84 BK 85 GR 84 BK 85 GR TO OTHER SCHOLAR UNIT DAMPER TO DISPLAY ETHERNET 128 GR 0 GR 0 GR 59 RD 53 RD 38 O 38 O 53 RD 60 Y 55 Y 128 GR...

Page 29: ...GR 59 RD 53 RD 38 O 38 O 53 RD 60 Y 55 Y 128 GR 135 BL 140 BL 56 BK 500 Crankcase Heater 131 O 114 Y 114 Y 106 WT 107WT 108 WT 106 WT 107 WT 108 WT 25 Y 26 BR 26 BR 27 Y 27 Y 28 O 28 O 55 Y 203 RD 10...

Page 30: ...Scholar V VAIVA Maintenance Service Manual 10 2017 Rev 2 30 Figure 14 EEV Controller Display...

Page 31: ...ucer RH Transducer 0 20 ma Blower Speed 0 20 ma Comp Speed Input Status Lights Output Status Lights Compressor Enable Reversing Valve Reheat Valve Outdoor Fan 1 Resistance Heat Contactor Outdoor Fan 2...

Page 32: ...w speed control and capacity variation A 24 VAC run signal comes from the PLC to tell the compressor to operate A 4 20 milliamp analog signal comes from the PLC to set the correct speed Since the driv...

Page 33: ...the Bristol compressor drive Fault LED Fault Description 1 Not Ready 1 See the Not Ready description above 2 DI LO input 2 LO input status invalid based on control mode 3 DI HI input 3 HI input status...

Page 34: ...n the system Look at EEV display Part 18 Is superheat being controlled If superheat is very high or valve is open 100 a leak may be indicated Look at refrigeration sight glass Part 15 If lots of bubbl...

Page 35: ...sing the Reset button on the main screen If the problem continues the condenser blower s may be running improperly On a condenser system with dual blowers one of the blowers is cycled on and off based...

Page 36: ...valve gets energized The cycle rate is controlled by the PLC and the supply air thermocouple Water is on the floor 1 This is likely a condensate drainage issue Check all condensate hoses and traps Be...

Page 37: ...two return filters in the upper indoor section of the unit A filter is located behind each of the return grilles To remove the filters open both doors and slide the filters out as shown below RETURN A...

Page 38: ...Service Manual 10 2017 Rev 2 38 1 Remove the two screws at the top and bottom of each panel to access the filters 2 Slide the filters out to inspect replace After inspecting replacing of the filters...

Page 39: ...ess to the Indoor Coils for Cleaning Tools Required 5 16 Nut Driver 1 Remove the top cover fifteen screws 2 Remove the filters 3 Carefully spray the coils with Marvair approved cleaning solution Use c...

Page 40: ...o Outdoor Coils for Cleaning Tools Required 5 16 Nut Driver 1 Remove the two screws that hold the condensate line to the middle front door Note Do not remove or disconnect the condensate tubing 2 Remo...

Page 41: ...removed carefully spray the coils with an industry approved cleaning solution COIL COIL E Removal of Fresh Air Intake Blower Motor Tools Required 5 16 Nut Driver Slotted Screw Driver Clippers to Cut W...

Page 42: ...Maintenance Service Manual 10 2017 Rev 2 42 2 Remove the eight screws that hold the lower plenum front cover 3 Cut tie wrap that hold wires 4 Disconnect the four wires at the butt splice 5 Slide the b...

Page 43: ...Ventilation Option and access to 460v transformer and to fresh air exhaust motor Tools Required 5 16 Nut Driver 5 16 Socket Wrench or Open End Wrench Clippers to Cut Wire Tie 1 Remove ventilation filt...

Page 44: ...r V VAIVA Maintenance Service Manual 10 2017 Rev 2 44 4 Remove the filter rack assembly thirteen screws 5 Remove the two GreenWheel dividers one on the left and one on the right Each divider has two s...

Page 45: ...ct wires to the GreenWheel drive motor or the damper motor 7 While lifting up on the horizontal divider panel that rests on the ventilation module pull the ventilation module out of the unit Access to...

Page 46: ...e Service Manual 10 2017 Rev 2 46 G Removal of the Indoor Blower Motor Tools Required 5 16 Nut Driver Clippers to Cut Wire Tie 1 Remove the top cover fifteen screws 2 Disconnect the two electrical har...

Page 47: ...t two in the front and two on the right that hold the blower motor to the top panel These screws penetrate the blower motor flange vertically into the top panel 5 Pull forward on the blower Use cautio...

Page 48: ...r Assembly 2 2 1 2 3 3 1 2T Units Only Tools Required 7 16 Socket 5 16 Nut Driver 1 Remove the two screws that hold the condensate line to the middle front door Note Do not remove or disconnect the co...

Page 49: ...2017 Rev 2 3 Disconnect the flexible duct by removing the screws at the top and bottom of the duct 4 Remove the six bolts that hold the fan motor assembly It is necessary to hold the nut on the backs...

Page 50: ...to the middle front door Note Do not remove or disconnect the condensate tubing 2 Remove the eighteen screws that hold the door and carefully remove the door 3 Disconnect the flexible duct by removin...

Page 51: ...rvice Manual 10 2017 Rev 2 Electrical Plugs Remove Three Screws on Each Side J Removal of the Fresh Air Exhaust Fan Motor Tools Required 5 16 Nut Driver No 2 Phillips Head Screwdriver 1 Remove the 18...

Page 52: ...ual 10 2017 Rev 2 52 2 Remove the lower plenum front cover eight screws 3 Remove the lower plenum divider access door ten screws 4 Remove yellow flexible duct 5 Disconnect wires to the fan motor 6 Rem...

Page 53: ...x Tools Required 5 16 Nut Driver 1 Remove the eight screws that hold the control box cover panel Location of major components 1 Compressor reversing valve and coil Schrader fittings and condensate dra...

Page 54: ...oil Filter drier High pressure switch Loss of charge switch Outdoor orifice Defrost sensor Flexible duct for ventilation air FILTER DRIER SIGHT GLASS HIGH PRESSURE SWITCH COMPENSATOR TANK LOSS OF CHAR...

Page 55: ...Coil Indoor blower motor assembly and Thermal Expansion Valve AIR FILTER INDOOR COIL INDOOR BLOWER ASSEMBLY INDOOR COIL SUCTION PRESSURE TRANSDUCER CAPILLARY TUBES SUCTION TEMPERATURE SENSOR ELECTRONI...

Page 56: ...cc Press once to enter Unoccupied Mode In this mode fresh air is turned off and set points for an empty room are installed Selection is shown above button g Precond ON Press once to allow for pre cond...

Page 57: ...oil enclosure iii Outside Coil 1 Located in distributor tube bundle serving Coil 2 iv Outside Coil 2 Located in distributor tube bundle serving Coil 2 b Temperature and Relative Humidity Transmitter t...

Page 58: ...midity transmitter into a usable number for control It is specific to the transmitter being used and should not be changed unless a different transmitter is substituted d RH Intercept This is a consta...

Page 59: ...ll for cooling the hot gas reheat valve is turned on to heat the air back up to the set point The Hot gas Reheat Diff is applied to the cooling set point to establish a temperature where the hot gas v...

Page 60: ...l voltage increases incrementally by 4 volts every 20 seconds adjustable to a maximum of 9 volts Scholar V Cooling Control Method Deadband Setpoint Below the lower point of the deadband the compressor...

Page 61: ...the temperature is in side the control band the speed control voltage remains fixed until the temperature again moves outside the band e or Time sec This is the time increment that elapses between co...

Page 62: ...ol SP Un Occ F Cooling set point for Unoccupied Mode d Heat SP Un Occ F Heating set point for Unoccupied Mode e RH Set Point Relative humidity set point for all modes f Low Amb Override F Outside temp...

Page 63: ...nt stored in the indoor coil This is only active if the Blower Auto mode is chosen on Screen 1 Main Screen f Coil Thaw Time min A freeze stat is located in contact with the fins of the indoor coil Thi...

Page 64: ...r the outside coil which removes the ice During this cycle the outdoor fan s or blower s turn off to maximize the heat forced into the coil a Defrost Run Time min This is the maximum time that the uni...

Page 65: ...des a way to calibrate the various measured temperatures if required The offset number can be either positive or negative and is added to the value being measured by the sensing element For example if...

Page 66: ...ribed in Screen 4 Differentials and Deadbands d Electric Re heat Set Diff F This value establishes the temperature at which the electric heat will come on if enabled The electric heat ON point is calc...

Page 67: ...ptable minimum value The purpose of the condenser coils is to transfer rejected heat to the outside ambient air Two condenser blowers are used to move outside air over the outdoor heat exchanger coils...

Page 68: ...ambient temperature is high if Fixed is chosen the compressor will ramp up to the maximum speed associated with the Heating Max Volts Linear Heating Max With this method the maximum speed of the compr...

Page 69: ...s considerably higher than the cooling set point the com pressor speed will ramp up slowly until the maximum control voltage is provided to the compressor controller This sets the maximum compressor s...

Page 70: ...ely equal to the set point inside the control band explained in Screen 4 the compressor speed stops changing and stays fixed As the compressor speed changes the indoor blower speed will also change Th...

Page 71: ...ndenser blowers may cycle off to control head pressure 2 Electronic Expansion Valve controller is autonomous and is always active 3 Ventilation is a customer choice See Occupied Unoccupied and Pre con...

Page 72: ...e Manual 10 2017 Rev 2 72 APPENDIX A HMI FAULT SCREENS These splash screens appear on the HMI when faults occur in the unit Auto Reset will attempt operation again after a time out period Lock out req...

Page 73: ...2 APPENDIX B ELECTRONIC EXPANSION VALVE EEV USER MANUAL To download a PDF of the complete user s manual for the EEV used in the Scholar V use the link below http www carelusa com documents 10191 0 03...

Page 74: ...under this warranty Airxcel Commercial Group will honor its warranty and furnish the required replacement part All costs for shipment and risk of loss during shipment of the product to Airxcel Commer...

Page 75: ...75 Scholar V VAIVA Maintenance Service Manual 10 2017 Rev 2 APPENDIX D PROCEDURE FOR FILING A WARRANTY CLAIM...

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