Marvair AVPA24 User manual

Classic Heat Pump
Installation & Operation Manual
Vertical Wall-Mount Heat Pumps
MODELS AVPA 24-30-36-42-48-60, HVPA 24-30-36-42-49-60 & HVPSA36-42-49-60
(Includes units with the GreenWheel®ERV and Hot Gas Reheat)
Model AVPA36
P/N 81025 4/2012 rev. 4
Manufactured By:
Marvair®Division of AIRXCEL®, Inc.
P.O. Box 400 • Cordele, Georgia 31010
156 Seedling Drive • Cordele, Georgia 31015
[phone] • Fax [phone]
E-mail: [e-mail] • Internet: www.marvair.com
The most current version of this manual can be found at www.marvair.com.

2Classic Manual 4/2012 rev. 4
Specications subject to change without notice.
© 4/2012, Marvair®, Division of AIRXCEL™, Inc.
How To Use This Manual
This manual is intended to be a comprehensive guide to the installation of the Marvair® Classic line of vertical
packaged heat pumps. It contains installation, troubleshooting, maintenance, warranty, and application information.
The information contained in this manual is to be used by the installer as a guide only. This manual does not
supersede or circumvent any applicable national or local codes. For information on the efciency, cooling and
heating performance, please refer to the Classic AVPA and HVPA Product Data Sheets. The most current version of
all Marvair literature can be found on our website at www.marvair.com.
If you are installing the Classic, rst read Chapter 1 and scan the entire manual before beginning the installation
as described in Chapter 2. Chapter 1 contains general, descriptive information and provides an overview which
can speed up the installation process and simplify troubleshooting.
If a malfunction occurs, follow this troubleshooting sequence:
1. Make sure you understand how the Classic works (Chapters 1 & 3).
2. Identify and correct installation errors (Chapter 2).
3. Refer to the troubleshooting information in Chapter 4.
4. Identify defective part(s). (Chapter 5).
If you are still unable to correct the problem, contact the Factory at 1-800-841-7854 for additional
assistance.
Please read the following “Important Safety Precautions” before beginning any work. Failure to follow
these rules may result in death, serious bodily harm, property damage and damage to the equipment.
Important Safety Precautions
1. USE CARE when LIFTING or TRANSPORTING equipment.
2. TRANSPORT the UNIT UPRIGHT. Laying it down on its side may cause oil to leave the compressor and
breakage or damage to other components.
3. TURN ELECTRICAL POWER OFF AT THE breaker or fuse box BEFORE installing or working on the
equipment. LINE VOLTAGES ARE HAZARDOUS or LETHAL.
4. OBSERVE and COMPLY with ALL applicable PLUMBING, ELECTRICAL, and BUILDING CODES and
ordinances.
5. SERVICE may be performed ONLY by QUALIFIED and EXPERIENCED PERSONS.
* Wear safety goggles when servicing the refrigeration circuit
* Beware of hot surfaces on refrigerant circuit components
* Beware of sharp edges on sheet metal components
* Use care when recovering or adding refrigerant
6. Use COMMON SENSE - BE SAFETY-CONSCIOUS
This is the safety alert symbol . When you see this symbol on the Classic unit and in the instruction
manuals be alert to the potential for personal injury. Understand the signal word DANGER, WARNING
and CAUTION. These words are used to identify levels of the seriousness of the hazard.
Failure to comply will result in death or severe personal injury and/or property damage.
Failure to comply could result in death or severe personal injury and/or property damage.
Failure to comply could result in minor personal injury and/or property damage.
IMPORTANT is used to point out helpful suggestions that will result in improved installation, reliability or
operation.
!DANGER
!WARNING
!CAUTION
IMPORTANT

3Classic Manual 4/2012 rev. 4
Ta b l e o f Co n T e n T s
Chapter 1 - Classic Description & Specications
General Description1.1 .........................................................................................................................5
Air Flow, Weights and Filter Sizes1.2 ..................................................................................................6
General Operation1.3 ...........................................................................................................................7
Controls - Standard - PC Board1.4 .......................................................................................................9
Options1.5 ..........................................................................................................................................14
Economizer 1.6 ...................................................................................................................................15
Chapter 2 - Installation
2.1 Equipment Inspection ....................................................................................................................17
2.2 Installation Requirements ..............................................................................................................17
2.3 Installation Materials ...................................................................................................................19
2.4 Porting and Duct Work .................................................................................................................21
2.5 Fresh Air Hood installation ..........................................................................................................22
2.6 Bracket Installation ......................................................................................................................22
2.7 Mounting the Unit ........................................................................................................................23
2.8 Electrical Connections ...................................................................................................................24
Chapter 3 - Start-Up
3.1 Check-Out of Cooling Cycle ........................................................................................................27
3.2 Check-Out of Heating Cycle .........................................................................................................28
3.3 Discharge Air Adjustment for Modulating Hot Gas Reheat (HGR) Valve ...................................28
3.4 Ventilation System Set Up ............................................................................................................30
Chapter 4 - Troubleshooting
4.1 Overview .......................................................................................................................................32
4.2 Failure Symptoms Guide ...............................................................................................................33
4.3 Compressor Troubleshooting ........................................................................................................34
4.4 Electric Heat Control .....................................................................................................................35
Chapter 5 - Electrical Schematics
5.1 Electrical Schematics ....................................................................................................................36
Chapter 6 - Periodic Maintenance Requirements
6.1 Scheduled Maintenance .................................................................................................................42
WARNING
• If the information in these instructions are not followed exactly, a re 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 qualied installer or service
agency in accordance with these instructions and in compliance with all codes and
requirements of authorities having jurisdiction.
INSTALLER: Afx the instructions on the inside of the building adjacent to the thermostat.
END USER: Retain these instructions for future reference.

4Classic Manual 4/2012 rev. 4
Chapter 7 - Warranty Information
7.1 Standard Product Warranty ...........................................................................................................43
Exploded Views & Parts Lists ..............................................................................................................44
Appendix A - Installation Instructions of Field Installed Electric Heat .................................................44
fi g u r e s
Figure 1 PC Control Board ........................................................................................................... 14
Figure 2 Enthalpy Sensor Temperature Control Points ..................................................................16
Figure 3 Fresh Air Hood Damper ..................................................................................................22
Figure 4 Classic Heat Pump Wall Mounting Detail ......................................................................23
Figure 5a Humidity Control Wiring Detail ......................................................................................26
Figure 5b Thermostat Connection Diagram .....................................................................................26
Figure 6 Temperature Sensor Wires - Modulating HGR Valve ....................................................29
Figure 7 Desired Temperature Set Point - Modulating HGR Valve ..............................................29
Figure 8 Damper Adjustment ........................................................................................................30
Figure 9 Damper Air Path ..............................................................................................................31
Figure 10 Typical Configuration for Single Element Heater ...........................................................35
Figure 11a Typical 1ø Electrical Schematic Diagram
Classic Heat Pump (Models AVPA) with Manual Outside Air Damper ........................37
Figure 11b Typical 208/230v. 3ø Electrical Schematic Diagram
Classic Heat Pump (Models AVPA) ...............................................................................38
Figure 11c Typical 460v. 3ø Electrical Schematic Diagram
Classic Heat Pumps, Models AVPA, with the PC Control Board ..................................39
Figure 11d Typical Electrical Schematic Diagram
Classic Heat Pump (Models HVPA) with Manual Outside Air Damper ........................40
Figure 11e Typical Electrical Schematic Diagram
Classic Heat Pump (Models HVP) with Economizer ......................................................41
Ta b l e s
Table 1a CFM @ External Static Pressure - AVPA ....................................................................... 6
Table 1b CFM @ External Static Pressure - HVPA & HVPSA .................................................... 6
Table 2a Ship Weight - AVPA ...........................................................................................................6
Table 2b Ship Weight - HVPA & HVPSA ........................................................................................7
Table 3 Filter Sizes - AVPA, HVPA & HVPSA ..............................................................................7
Table 4a Minimum Clearances - AVPA ..........................................................................................18
Table 4b Minimum Clearances - HVPA .........................................................................................18
Table 5 Voltage Limitations ..........................................................................................................19

5Classic Manual 4/2012 rev. 4
Classic Heat Pump
Description and Specications
1.1 General Description
The Marvair® Classic Heat Pumps are high efficiency, vertical wall mounted heat pumps that provide
heating, cooling and ventilation for a wide range of applications. Nominal cooling capacities range
from 24,000 to 60,000 BTUH. The AVPA Series consists of units with EER's from 9.0 to 9.75.
The HVP Series feature units with EER's of up to 11.00 and quiet operation. Resistance heating are
available in all models. Please see appendix A for the installation instructions on field installing electric
heaters. HVPSA36-42-49-60 units have 2-stage compressors with first stage cooling approximately
65% of the total cooling capacity. The two stage compressor can reduce energy costs and is able to
more precisely match the cooling and dehumidifying capacity of the heat pump with the heat load
in the classroom.
Classic heat pumps are designed for easy installation and service. All units have built-in side mounting
flanges and are shipped with a bottom support bracket. The unit has been factory charged. Service
ports have been provided for field service, if required. All internal wiring is complete.
The Classic heat pumps are available in a wide variety of styles and configurations to meet the various
ventilation and cooling requirements. For school classrooms, models are available to comply with
the ASHRAE 62-1999 standard, “Ventilation for Acceptable Indoor Air Quality.” Where cooling is
required during cool or cold weather, e.g., telecommunication shelters, a factory-installed economizer
can be used. To insure proper operation and optimum performance, all outside air ventilation packages
and the economizer are non-removable, factory installed and tested. Instructions for the HVP models
with the GreenWheel® ERV and the GreenPac HGR are included in this manual.
All Classic heat pumps are tested and certified for efficiency and capacity in accordance with the
ANSI/AHRI (Air-Conditioning, Heating and Refrigeration Institute) Standard 390-2003 (Single
Package Vertical Units). All AVPA and HVPA units meet or exceed the efficiency requirements of
ANSI/ASHRAE/IESNA 90.1.2007. Classic heat pumps are listed by ETL and tested to UL standard
1995, 2nd Edition. Classic heat pumps are commercial units and are not intended for use in residential
applications.
AVPA Model Identification
A
VP A HP ••• •
Special Option Code
Electric Heat (kW)
000 = No Heat 040 = 4 kW 050 = 5 kW 060 = 6 kW 090 = 9 kW 100 = 10 kW 120 = 12 kW 150 = 15 kW
Power Supply
A = 208/230V, 1 Ph, 60 Hz C = 208/230V, 3 Ph, 60 Hz D = 460V, 3 Ph, 60 Hz
System Type
Heat Pump
Nominal Cooling*
24 = 24,000 BTUH 30 = 30,000 BTUH 36 = 36,000 BTUH 42 = 42,000 BTUH 48 = 48,000 BTUH 60 = 60,000 BTUH
A
ir Source Vertical Package
R = Electric Reheat Dehumidification U = Scroll Compressor G = HGR (Hot Gas Reheat)
Ventilation Code
N = 0-15% fresh air with manual damper, no presure relief
Y = 0 to 450 cfm* of outside air, field adjustable, manual damper, no pressure relief
Z = 0 to 450 cfm* of outside air, field adjustable, manual damper, includes pressure relief
B = Motorized two position damper (open & closed) capable of 0 to 450 cfm* of outside air, includes pressure relief
C = Economizer - 100% rated airflow of outside air used for cooling when outside conditions are suitable
H = GreenWheel® Energy Recovery Ventilator
J = PowerVent with motorized damper. Includes pressure relief.
••S
R410-A Refrigerant
Refrigerant
Two-Stage Compressor

6Classic Manual 4/2012 rev. 4
HVPA Model Identification
HVPAHP ••• •
Special Option Code
Electric Heat (kW)
000 = No Heat 040 = 4 kW 050 = 5 kW 060 = 6 kW 090 = 9 kW 100 = 10 kW 120 = 12 kW 150 = 15 kW
Power Supply
A = 208/230V, 1 Ph, 60 Hz C = 208/230V, 3 Ph, 60 Hz D = 460V, 3 Ph, 60 Hz
System Type
Heat Pump
Nominal Cooling*
24 = 24,000 BTUH 30 = 30,000 BTUH 36 = 36,000 BTUH 42 = 42,000 BTUH 49 = 49,000 BTUH 60 = 60,000 BTUH
High Efficiency Vertical Package
•
Series
R = Electric Reheat Dehumidification U = Scroll Compressor G = HGR (Hot Gas Reheat)
Ventilation Code
N = 0-15% fresh air with manual damper, no presure relief
Y = 0 to 450 cfm* of outside air, field adjustable, manual damper, no pressure relief
Z = 0 to 450 cfm* of outside air, field adjustable, manual damper, includes pressure relief
B = Motorized two position damper (open & closed) capable of 0 to 450 cfm* of outside air, includes pressure relief
C = Economizer - 100% rated airflow of outside air used for cooling when outside conditions are suitable
H = GreenWheel® Energy Recovery Ventilator
Q = GreenCube ERV
J = PowerVent with motorized damper. 0-450 cfm of outside air
••S
R410-A Refrigerant
Refrigerant
Two-Stage Compressor
Serial Number Date Code
A = January
B = February
C = March
D = April
E = May
F = June
G = July
H = August
J = September
K = October
L = November
M = December
L = 2000
M = 2001
N = 2002
P = 2003
R = 2004
S = 2005
T = 2006
U = 2007
V = 2008
Y = 2009
Z = 2010
A = 2011
B = 2012
C = 2013
1.2 Air Flow, Weights and Filter Sizes.
Table 1a. Air Flow (Cubic Feet per Minute) AVPA
MODEL External Static Pressure (WET COIL)
0.10 0.20 0.25 0.30 0.40 0.50
AVPA24 860 810 740 670
AVPA30 1100 1000 960 920 810
AVPA36 1310 1220 1185 1150 1060
AVPA42 1650 1585 1520 1450 1360
AVPA48 1900 1830 1760 1700 1620
AVPA60 1900 1830 1760 1700 1620
Air flow ratings of 208-230v. Units are at 230v. Air flow ratings of 480 v. units are at 460 volts. Operation of units at a different
voltage from the rating point will affect air flow.
Table 1b. Air Flow (Cubic Feet per Minute) HVPA & HVPSA
MODEL External Static Pressure (WET COIL)
0.10 0.20 0.25 0.30 0.40 0.50
HVPA24 800 770 725 680 600 500
HVPA30 1200 1100 1050 1000 900 800
HVPA36/HVPSA36 1290 1170 1115 1060 1000 920
HVPA42/HVPSA42 1500 1360 1295 1230 1160 1070
HVPA48/HVPSA48 1900 1800 1700 1600 1500 1350
HVPA60/HVPSA60 2200 2100 2000 1900 1800 1650
Air flow ratings of 208-230v. Units are at 230v. Air flow ratings of 480 v. units are at 460 volts. Operation of units at a different
voltage from the rating point will affect air flow.
Table 2a. Ship Weight (lbs) - Model AVPA
MODEL 24 30/36 42 48 60
Classic with "N" Ventilation Conguration 285 375 515 545 590
Classic with "Y", "Z", "B", "J" & "C"
Ventilation Conguration 315 405 545 575 590

7Classic Manual 4/2012 rev. 4
1.3 General Operation
Refrigerant Cycle
The Classic heat pumps use R-410A refrigerant in a conventional vapor-compression refrigeration
cycle to transfer heat. In the cooling mode, a double blower assembly blows indoor air across the
evaporator (indoor coil). Liquid refrigerant passing through the evaporator is boiled into gas by heat
removed from the air. The warmed refrigerant gas enters the compressor where its temperature and
pressure are increased. The hot refrigerant gas condenses to liquid as heat is transferred to outdoor
air blown across the condenser (outdoor coil) by the condenser fan. Liquid refrigerant is metered
into the evaporator through a metering device to repeat the cycle. In the heating mode, the process
is reversed.
Models HVPSA have 2-stage compressors with first stage cooling capacity approximately 65% of
the total cooling capacity. The 2-stage compressor provides lower start-up amps and is able to match
more precisely the cooling capacity of the heat pump with the heat load in the building. The 2-stage
is only operational in the cooling mode. A two stage cooling thermostat is required for all 2-stage
compressors.
Heating Mode
During heating mode a special reversing valve reverses the flow of refrigerant through the system
exchanging the roles of the condenser and evaporator. Now the outdoor coil becomes the evaporator
and the indoor coil becomes the condenser. The refrigerant then flows through the outdoor coil, picks
up heat and becomes vaporized. The vapor then enters the compressor where it is compressed to a
higher temperature. Next it is pumped to the indoor coil where the heat will be released into the room.
The compressed refrigerant vapor will condense to its liquid state as it gives up heat. Finally, liquid
flows through a metering device into the evaporator where the cycle will be repeated.
Optional electric strip heat is available for all models. Please see Appendix A for instructions on field
installation of electric heat.
Table 2b. Ship Weight (lbs) - Model HVPA & HVPSA
MODEL 24 30/36/42 49 60
Classic with "N" Ventilation
Conguration 375 560 610 625
Classic with "Y", "Z", "B", "J" & "C"
Ventilation Conguration 405 590 625 640
Table 3. Filter Size (inches) - Model AVPA
MODEL FILTER TYPE INCHES MILLIMETERS PART
NUMBER
FILTERS PER
UNIT
MERV
RATING
AVPA24 Return Air Filter 25 x 16 x 1 635 x 406 x 25 80135 1 7
AVPA30/36 & HVPA24 Return Air Filter 30 x 16 x 1 762 x 406 x 25 80136 1 7
AVPA42/48/60,
HVPA30/36/42 &
HVPSA36/42
Return Air Filter 36½ x 22 x 1 927 x 559 x 25 80139 1 7
HVPA49/60 &
HVPSA49/60
Return Air Filter 18 x 24 x 1 457 x 610 x 25 81199 2 7
Intake Air Filter* 14 x 14 x 1 356 x 356 x 25 80192 1N/A
AVPA24/30/36
& HVPA24 with
GreenWheel ERV
Return Air Filter 27½ x 13½ x 1 699 x 343 x 25 80769 1 7
Intake Air Filter* 14 x 14 x 1 356 x 356 x 25 80192 1N/A
AVPA42/48/60,
HVPA30/36/42 &
HVPSA36/42 with
GreenWheel ERV
Return Air Filter 36½ x 22 x 1 927 x 559 x 25 80139 1 7
Intake Air Filter* 14 x 14 x 1 356 x 356 x 25 80192 1N/A
*Units with the GreenWheel ERV

8Classic Manual 4/2012 rev. 4
Ventilation Options
• Manual damper capable of up to 15% of rated airflow of outside air; field adjustable, no pressure
relief. (Standard - Ventilation Configuration N)
• Manual damper capable of 0 to 450 cfm (maximum of 40% of rated airflow) of outside air; field
adjustable, no pressure relief. (Optional - Ventilation Configuration Y)
• Manual damper capable of 0 to 450 cfm (maximum of 40% of rated airflow) of outside air; field
adjustable, includes pressure relief. (Optional - Ventilation Configuration Z)
• Motorized, two position damper (open and closed) capable of 0 to 450 cfm (maximum of 40%
of rated airflow) of outside air; includes pressure relief. A 24-volt actuated motor controls the
damper from an external input such as: a time clock, CO2 sensor, energy management system or
manual switch. (Optional - Ventilation Configuration B)
• PowerVent with motorized damper capable of 0-450 cfm of outside air, not to exceed 40% of
rated airflow. Includes pressure relief. Ventilation intake and exhaust blowers with single motor
controller. Optional second controller for exhaust air. (Optional - Ventilation Configuration J)
GreenWheel® ERV Operation (Ventilation Option "H")
The Marvair® GreenWheel® ERV is a total energy (both sensible and latent) wheel that reduces both
construction and operating cost while ventilating the classroom to ASHRAE 62-1999 requirements.
The use of the GreenWheel ERV reduces the energy load of the outside air. Exhausting stale, inside
air keeps indoor pollutants and harmful gases to a minimum. The Marvair GreenWheel ERV has
been tested and certified according to ARI Standard 1060.
How It Works
During the summer, cool dry air from the classroom is exhausted through the GreenWheel® ERV
to the outside. As the air passes through the rotating wheel, the desiccant becomes cooler and drier.
Simultaneously, hot humid air is being pulled across the rotating wheel. The cool, dry desiccant
absorbs moisture and heat from the incoming air. The cooler, drier air is mixed with the return air
from the classroom and distributed throughout the room.
In the winter, warm moist air is exhausted through the GreenWheel® ERV to the outside. As the air
passes through the rotating wheel, the desiccant becomes warmer and absorbs moisture. Simultaneously,
cold dry air is being pulled across the rotating wheel. The cold, dry air absorbs heat and moisture
from the desiccant. The warmed air is mixed with the return air from the classroom and distributed
throughout the room.
Quality Components
The GreenWheel® module consists of a desiccant wheel, two blowers and the drive motor and belt.
The two blowers simultaneously pull fresh air from outside and exhaust air from the classroom
through the rotating wheel. Two variable speed blowers ensure that up to 450 CFM of outside air
can be brought into the room and the indoor air is properly exhausted. Variable speed blowers permit
that the desired quantity of outside air is delivered into the room. Optional independent exhaust air
blower control allows positive pressurization of the classroom, i.e., more outside air can be introduced
through the GreenWheel® ERV than is exhausted.
GreenCube ERV (Ventilation Option “Q”)
The Marvair GreenCube ERV is an enthalpy plate heat exchanger that transfers both sensible and

9Classic Manual 4/2012 rev. 4
latent energies between outgoing and incoming air streams in a cross flow arrangement. Except
for two air movers, it has no moving parts. The media is impregnated with a RC134 polymeric
desiccant that exchanges water by direct vapor transfer using molecular transport without the need
of condensation. The GreenCube ERV will operate at temperatures as low as 10°F without a defrost
mechanism. In addition, the desiccant is a bactericide. Two MERV 6 type filters are used on both
sides of the enthalpy core. The fresh air and exhaust motors have independent speed controllers to
permit each of the motors to be regulated independently.
The GreenCube ERV is available in heat pumps with nominal cooling capacities of 36,000 thru 60,000
BTUH. All Classic heat pumps with the GreenCube ERV are in the HVPA49/60 cabinet.
Hot Gas Reheat (HGR) Dehumidification Mode (Special Option “G”)
When the HGR is in the dehumidification mode, the hot gas reheat (HGR) coil is energized. The
cooled, dehumidified air exits the evaporator coil and is blown through the HGR coil. This coil is
sized to the sensible capacity of the unit. The heat in the HGR coil is transferred to the air stream.
The use of the HGR coil allows the indoor humidity of the classroom to be maintained at or below a
certain set humidity set point without over cooling the classroom. These units can not add humidity
to the classroom.
The operation of the HGR coil is controlled by a humidity controller. If the humidity rises above the
set point on the controller and the temperature in the classroom is satisfied, both mechanical cooling
and the HGR coil operate to temper the air and lower the humidity. If the temperature in the classroom
rises above or falls below the set point of thermostat and the unit is operating in the dehumidification
mode, the need for cooling or heating will override the call for dehumidification and the HGR coil
is disengaged until the thermostat is satisfied. This assures the classroom temperature is maintained
as first priority and humidity control is second.
The humidity controller or BAS control is required for proper operation of the HGR coil.
Economizer Operation - Cooling Cycle
(Classic Heat Pump with Economizer only)
The economizer is a regulated damper system with controls. The damper regulates the circulation
of outside air into the enclosure (when the outdoor air conditions are suitable) to reduce the need
for mechanical cooling, save energy, and extend compressor life.
Depending upon the options selected, the damper responds to either enthalpy or dry bulb temperature
of the outdoor air. On a call for cooling from a space thermostat, it operates as follows:
When the enthalpy of the outdoor air is below the set point, the outdoor air damper is proportioned
open (and return air damper is proportioned closed) to maintain between 50oF and 56oF at the mixed/
discharge air sensor.
When the enthalpy of the outdoor air is above the set point, the outdoor air damper closes to its
minimum position. A call for cooling from the space thermostat brings on mechanical cooling.
An optional built-in adjustable minimum position potentiometer, p/n 70012, controls the amount of
outdoor air admitted to meet minimum ventilation requirements.
1.4 Standard Controls- PC Board
Description of Operation
The PC board controls the operation of the indoor blower, the compressor and the reversing valve

10 Classic Manual 4/2012 rev. 4
while providing high pressure, loss of charge protection with an integral defrost function. Upon a
call for mechanical cooling or heating, the controller will energize the compressor when a 24 VAC
signal is applied to the “Y” terminal provided that all time delays and fault conditions are satisfied. It
will energize the indoor blower when a 24 VAC signal is applied to the “G” terminal. The reversing
valve will be energized when a 24 VAC signal is applied to the “O” terminal. Electric heat (EH) will
be energized when a 24 VAC signal is applied to the “W2” terminal. The control will monitor the
status of the loss of charge switch and the high pressure switch. If either of these inputs recognize
a fault, the compressor will turn off and the anti-short cycle delay will be initiated. If any of these
faults occur twice within a one hour period, the control will lock the compressor out until the power
is reset manually. Note: 24 VAC power must be continuously applied to “R” and “C”.
The board will also monitor the defrost sensor. If the defrost sensor senses a temperature of 32°F while
in the heat mode, it will initiate a pin selectable 30, 60, or 90 minute delay period. (Factory set at 60
minutes). If the sensor is still calling for defrost at the end of this delay period, it will de-energize
the outdoor fan and energize the reversing valve through the RV terminals. The defrost cycle will
terminate on time or temperature. It will have a maximum defrost run time of 10 minutes, however,
if the defrost sensor registers a temperature of 50°F or higher before the 10 minute maximum run
time, the defrost cycle will terminate. The EH terminals will also be energized during a defrost cycle
if the EHDD (Electric Heat During Defrost) jumper is in the “Yes” position.
The board also provides the ability to vary the speed of the indoor blower motor (electronically
commutated motors excepted) and to select the number of seconds the blower will run after the
compressor has turned off (Post Purge). The user can select whether the compressor and electric heat
operate simultaneously (the S-Circuit) and if electric heat operates during the defrost mode (EHDD).
The board can control the operation of a two position motorized damper to provide fresh air for
ventilation (DRO/DRC). In conjunction with an optional temperature sensor, the board will modulate
the speed of the outdoor fan motor to allow cooling during low ambient temperatures.
LED’s indicate power, operating status and high pressure or loss or charge lockout.
Functions
Lockout Protection
If either of the fault conditions (LPS or HPS) occurs twice within one hour, the control board will
enter into and indicate the lockout mode. In the lockout mode, the compressor is turned off. If there
is a call for indoor air flow “G”, the blower remains energized, the alarm output is energized and the
red LED will blink to indicate which fault has occurred. When the lockout condition is cleared, the
unit will reset if the thermostat is turned “Off” and back to “On” or when the power to the heat pump
is reset. With the control board, the user can select either normally closed or normally open contacts.
The heat pump is factory wired to be normally open.
Delay on Break
The board has an integral three minute delay on break (anti-short cycle) timer. This timer initiates
every time the compressor turns off to prevent a short cycle condition.
Loss of Charge (LPS) By-Pass Timer
The control includes a fixed, three minute Loss of Charge Switch (LPS) bypass timer. If the Loss of
Charge Switch is open on initial power up or while the compressor is running, the control will ignore
the fault for three minutes. If the fault still exists after three minutes, the control will de-energize the
compressor, register a loss of charge fault, and initiate the three minute anti-short cycle timer.

11 Classic Manual 4/2012 rev. 4
User Selectable Settings
The control board has three potentiometers (pots) that allow the user to select settings to optimize
the installation. See Figure 1 for location of the pots.
Delay on Make
The control has a pot settable 0.03 to10 minute delay on make timer that initiates upon initial power
up only. The factory set time is three minutes.
Post Purge Potentiometer
The board includes a pot settable 10-90 second post purge timer. When the signal at the “G” terminal
is removed, the indoor blower will remain energized for the amount of time selected by the pot. The
pot is factory set at ninety seconds.
Indoor Blower Motor Speed Control Potentiometer
The control has a speed control potentiometer for the indoor fan blower. The user can vary the speed
of the fan using this potentiometer from approximately 40% to 100% of rated air flow. Caution
should be used when slowing the speed of the indoor blower; sufficient air flow is critical to the
proper operation of the heat pump. Note: the indoor blower motor speed control is not functional on
the HVPA and HVPSA units with electronically commutated (EC) motors.
The control board has four operational modes that can be defined by the installer. These modes are
selected with jumpers. See Figure 1 for location of the jumpers. To change the factory setting, gently
pull the jumper and slide it onto the desired setting.
Damper Relay (Damper Relay Open-DRO /Damper Relay Closed-DRC)
The board has a two position, motorized fresh air damper (ventilation option “B”) from the “G” input
when this option is selected. It is pin selectable using a jumper to select “Yes” to enable it. When
“Yes” is selected, the control will energize the Damper Relay Open terminal when “G” is calling for
the damper to open. When the “G” signal is not present, the control will energize the Damper Relay
Closed terminal to close the damper. When “No” is selected, this feature is disabled. The factory
setting for the damper relay option is “No”.
Defrost Mode
The board has an integral defrost cycle that will be initiated by the Defrost Sensor (DS). If the
defrost sensor registers a temperature of 32°F while in the heat mode, it will initiate a pin selectable
30, 60, or 90 minute delay. The factory setting is 60 minutes. If the sensor is still calling for defrost
at the end of this delay, it will de-energize the outdoor fan, energize the reversing valve through
the RV terminals, and keep the compressor energized. The defrost cycle will terminate on time or
temperature. It will have a maximum defrost run time of 10 minutes, however, if the defrost sensor
registers a temperature of 50°F or higher before the 10 minute maximum run time, the defrost cycle
will terminate. If “Yes” has been selected for Electric Heat During Defrost (EHDD) and “No” selected
for the S-Circuit, the electric heat (EH) output will be energized during a defrost cycle to supply heat
while the coil defrosts.
Electric Heat During Defrost (EHDD)
The board provides the option of running the electric heat (EH) during a defrost cycle. There are

12 Classic Manual 4/2012 rev. 4
two options for the EHDD, “Yes” and “No”. If “Yes” is selected, the board will energize the EH
terminals during a defrost cycle. If “No” is selected, the EH terminals will not be energized during
a defrost cycle. The factory setting for EHDD is “No”. If the S-circuit is in the “Yes” position, the
EHDD function will be disabled.
S-Circuit
The S-Circuit prevents the compressor and electric heat from operating simultaneously. The S-Circuit
is pin selectable using a jumper to select “Yes” to enable this feature or “No” to disable it. When
“Yes” is selected, the control will not allow the compressor to run when there is a call for electric
heat at the W2 input. It will turn the compressor off until the call for W2 is satisfied. The factory
setting for the S-Circuit is “No”.
Test Mode
A jumper selectable test mode can be used by technicians for trouble shooting purposes. The test
mode reduces the delay on make and anti-short cycle timers to ten seconds, and the LPS bypass
becomes two minutes.
Internal Head Pressure Control (Requires optional coil sensor)
The control has an internal, fixed set point head pressure control designed to maintain a constant
head pressure under low ambient conditions. It will monitor a coil sensor that is inserted into the
condenser fan coil and modulate the speed of the fan motor accordingly to maintain a constant coil
temperature in turn stabilizing the head pressure. The fixed set point that the control will maintain is
100°F. The motor will have a minimum operating speed of 20%-30% of the full speed. It will also
incorporate a fixed hard start time of one second during which the condenser fan motor will turn on
full speed for one second at start up.
High Pressure Switch (HPS)
The high pressure switch is mounted on the compressor liquid line. The HPS terminals are on the
high pressure switch input. This input monitors the status of the high pressure switch and determines
when this fault condition is present. If the HPS is open on the initial “Y” call, the control board will
not allow the compressor to operate. If the HPS opens while the compressor is running, the control
board will turn the compressor off, register the first HPS fault, and initiate the 3 minute anti-short cycle
timer. If two HPS faults occur within a one hour period, the control will enter a HPS lockout condition
and energize the alarm contacts. The RED status LED will blink once to indicate this condition. The
lockout condition will only be reset by manually cycling power to the control to prevent destructive
short cycling. To reset the switch, turn primary power off, then back on or turn thermostat system
switch off, then back on.
The high pressure switch opens at 620 psig and closes at 420 psig.
Loss of Charge Switch (LPS)
The loss of charge switch is mounted on the compressor’s liquid line. The LPS terminals are the loss
of charge switch input. This input will be used to monitor the status of the loss of charge switch and
determine when a LPS fault is recognized. There is 3 minute loss of charge switch bypass timer. If
the LPS is open on the initial “Y” call or while the compressor is running, the control will ignore
the status of the LPS and not recognize a fault for 3 minutes. If the LPS is still open after 3 minutes,

13 Classic Manual 4/2012 rev. 4
the control will de-energize the compressor, register the first LPS fault, and initiate the 3 minute
anti-short cycle timer. If two LPS faults occur within a one hour period, the control will enter a LPS
lockout condition and energize the alarm contacts. The RED status LED will blink twice to indicate
this condition. The lockout condition will only be reset by manually cycling power to the control.
To reset the switch, turn primary power off, then back on or turn thermostat system switch off, then
back on.
The loss of charge switch opens at 40 psig and closes at 60 psig.
Status LED Blink Codes
There are two LEDs on the board. The green LED is used as a power indicator. The red LED is used
to indicate the two fault lockout conditions. During a HPS lockout, the red LED blinks once. During
a LPS lockout, the red LED blinks twice.
COLOR TYPE STATUS DESCRIPTION
Color Type Status Description
Green Power Constant On 24 VAC power has been applied
Green Status Constant On Normal Operation
Red Status 1 Blink High pressure switch has opened twice
Red Status 2 Blinks Loss of charge switch has opened twice
Red Status 3 Blinks Faulty or disconnected defrost sensor
Board Inputs
R and C. The R and C terminals are the input power terminals for the control. They will accept any
voltage between 19-32 VAC.
Y The “Y” terminal is the compressor input from the thermostat. Given that all time delay and fault
conditions are satised, the control will energize the compressor contactor through the “CC” terminals
when there is a 24 VAC signal present at the “Y” terminal.
W2 The “W2” terminal is the electric heat input from the thermostat. When the control receives a
call for “W2” from the thermostat, it will energize the EH terminal. When the S-Circuit is selected by
placing the jumper in the Yes position, the control will not allow the compressor to run simultaneously
with electric heat. The default setting for the S-Circuit is “No”. If “Yes” is selected for the S-circuit,
the EH output will not energize during defrost.
O The “O” terminal is the reversing valve input from the thermostat. When there is a 24 VAC signal
present at the “O” terminal, the control will energize the reversing valve through the “RV” terminals.
The control will also energize the “RV” terminals in heat mode during a defrost cycle.
G The “G” terminal is the indoor blower input from the thermostat. When there is a 24 VAC signal
present at the “G” terminal, the control will energize the indoor blower. When the signal at the “G”
terminal is removed, the fan will remain energized for the pot settable 10-90 second post purge period.
When the damper relay option is selected by placing the jumper in the “Yes” position, the control
will energize the DRO terminal with every “G” call to open the damper. When the “G” call is not
present, the control will energize the DRC terminal to close the damper. The default setting for the
damper relay option is “No”.

14 Classic Manual 4/2012 rev. 4
HPS High Pressure switch terminals are the high pressure switch input.
LPS Loss of Charge switch terminals are the loss of charge switch input.
DS The DS terminals are the defrost sensor input.
CS The CS terminals are the coil sensor (optional) input. This input will monitor the condenser
coil temperature to allow the head pressure control to modulate the speed of the fan and maintain a
constant head pressure.
Red Status LED
Damper Open/Damper Close S-Circuit
Electric Heat During Defrost
Test
Defrost Time Delay
(30-60-90 Minutes)
Green Power LED
Delay on Make PotIndoor Blower Speed Control Pot
Post Purge Pot
FS DS CS
Indoor Fan
Line 1
Line 2
Condenser Fan
Line 1
Line 2
1NC
1COM
1NO
DRC
DRO
EH
RV
CC
HPS Y LPS W2 O G
1Contacts
for Remote
Alarms
Figure 1 - PC Control Board
1.5 Options
Low Ambient Control
The low ambient control permits mechanical cooling when outdoor ambient temperatures are low.
The control uses a reverse-acting high pressure switch to cycle the condenser fan motor according
to liquid refrigerant pressure conditions. Switch closure and fan operation occurs when the pressure
reaches 400 PSIG. The switch opens again when the refrigerant pressure falls to 245 PSIG. Therefore,
the outdoor fan always starts after the compressor, and it will cycle frequently during normal
operation at low outdoor conditions.
Hard Start Kit
Used on single phase equipment to give the compressor higher starting torque under low voltage
conditions. Field installed only. (Not generally recommended for use on scroll compressor.)
Adjustable Outdoor Thermostat
Will not allow electric resistance heat to be energized unless the outdoor temperature is below the
desired set point. Field or factory installed. Available on all Classic units. P/N 93934
Single Point Feed

15 Classic Manual 4/2012 rev. 4
When multiple internal disconnects are used, single point feed permits only one field power supply
to heat pump. Field installed only. Available on all Classic units.
Energy Management System (EMS)
Relay to control the heat pump. Available in 24, 120 or 240 VAC. Field or factory installed.
Electric Reheat for Dehumidification
Control provides simultaneous operation of compressor when in cooling mode and the electric
elements to provide dehumidification without over cooling the room. The electric element (kW) must
be properly sized for each model for proper operation. Factory installed. Available on all Classic
units. Consult factory for details.
Hot Gas Reheat (HGR)
Marvair® heat pumps equipped with the Hot Gas Reheat (HGR) allow the indoor humidity of the
controlled environment to be maintained at or below a certain humidity set point. These units do not
have the ability to add humidity to the classroom.
Dehumidification is achieved by operating mechanical cooling in conjunction with a hot gas reheat
coil. The coil is sized approximately to the sensible capacity of the total tonnage of the machine.
Speed Control for GreenWheel®ERV Exhaust Blower
For separate control of the exhaust blower. When used, the standard speed controller operates the
intake blower and the optional second controller the exhaust blower. Individual blower control allows
positive pressurization of the classroom. Can be factory or field installed.
1.6 Economizer Operation and Components
Damper Actuator
The damper actuator is a motor that modulates the position of the damper blade. It is controlled by
the enthalpy controller and powered by the 24 VAC control transformer. 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.
Controls
The economizer is controlled by an enthalpy sensor or optional dry bulb sensor.
Economizer Changeover Control
The enthalpy sensor responds to the total heat content of the outdoor air to provide changeover to
outside air for free cooling. The change point is adjustable from 63°F @ 50% RH (full CCW) to 73°F
@ 50% RH (full CW). Refer to Figure 3.
Once the enthalpy sensor has selected outside air, the mixed air sensor will limit the air temperature
delivered to the space by modulating the damper blade to "mix in" a quantity of inside air to provide
a constant 50° to 63°F. (Adjustable minimum potentiometer is optional.)
The sensor modulates the position of the outside air damper in response to input from the enthalpy
and mixed air sensors. The controller is designed to maintain the supply air temperature between 50o
to 56oF by mixing warm indoor air with cooler outdoor air.
On a call for cooling from the wall-mounted thermostat, if outdoor conditions are suitable, the sensor
will open the damper and admit outside air (i.e., economizer cooling). If the outdoor ambient is too
hot or humid, the sensor will place the actuator in the closed or minimum open position and activate
mechanical cooling. The compressor is locked out during the economizer cooling mode.

16 Classic Manual 4/2012 rev. 4
Figure 2 - Enthalpy Sensor Temperature Control Points
Mixed Air Sensor
The mixed air sensor is a thermistor mounted on a bracket adjacent to the right side of the blower
assembly. The thermistor senses the air temperature entering the structure, and provides a signal
to the economizer controller for modulating the position of the damper. Nominal resistance of the
sensor at 77°F is 3000 ohms.

17 Classic Manual 4/2012 rev. 4
Installation
WARNING
Failure to observe and follow Warnings and Cautions and these Instructions could
result in death, bodily injury or property damage. Read this manual and follow its
instructions and adhere to all Cautions and Warnings in the manual and on the Marvair
unit.
2.1 Equipment Inspection
Concealed Damage
Inspect all cartons and packages upon receipt for damage in transit. Remove cartons and check for
concealed damage. Important: Keep the unit upright at all times. Remove access panels and examine
component parts. (Note: The bottom bracket is stored in the condenser air compartment. Remove them
before replacing the side screen). Inspect refrigerant circuit for fractures or breaks. The presence of
refrigerant oil usually indicates a rupture. If damage is apparent, immediately file a claim with the
freight carrier.
Units that have been turned on their sides or tops may have concealed damage to compressor motor
mounts, to the oil system or to other components. If the unit is not upright, immediately file a claim
for concealed damages and follow these steps:
1. Set unit upright and allow to stand for 24 hours with primary power turned on.
2. Attempt to start the compressor after 24 hours.
3. If the compressor will not start, makes excessive noise, or will not operate, return the unit to the
freight carrier.
General
1. Inspect unit for completeness. Check for missing parts (e.g. hardware). Refer to the installation
kit information in section 2.3.
2. Remove access panels and check for loose wires. Tighten screw connections.
3. Complete and mail the warranty registration card.
2.2 Installation Requirements
You must consider all of the following when choosing the installation site:
1. Noise. Install the unit so that the least amount of noise will be transmitted to inhabited spaces.
2. Condensate Drainage. Condensate produced during operation must be discharged to a suitable
drain.
3. Defrost Drainage. Ice build up sometime occurs during the heating cycle while in heat pump
operation. The automatic reversal (defrost control) of the heat pump cycle causes the ice to melt
so that the heat pump may operate efciently. Please keep this in mind while locating unit.
4. Placement.
A) Place the unit in a shaded area, if possible.
B) Install it above ground for protection against flooding.

18 Classic Manual 4/2012 rev. 4
C) The unit exhausts air. Be sure that the airflow is not impeded by shrubbery or other
obstructions.
D) When installing multiple units, please note the recommended clearances noted in Table 4.
5. Airflow Requirements:
Note the minimum CFM requirements (section 2.4). Keep duct lengths as short as possible. Do not
obstruct airflow through the unit.
Applications using duct work should be designed and installed in accordance with all applicable
safety codes and standards. Marvair® strongly recommends referring to the current edition of the
National Fire Protection Association Standards 90A and 90B before designing and installing duct
work. 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, and adequate return and filter areas. Duct work must be of correct material and
must be properly insulated. Duct work must be constructed of galvanized steel with a minimum
thickness of .019". Duct work must be firmly attached, secured, and sealed to prevent air leakage.
See section 2.4 for additional duct work requirements.
6. Clearances:
When facing the unit from the outside, the minimum clearances are found below. Note the minimum
clearances required for proper operation and service (Tables 4a & 4b below).
MODEL
Min. Clearance
From the Front
Min. Clearance
Around Sides
(Single Unit)
Min. Clearance
Between Sides
(Two Units)
Min. Space
Above Unit
24 42 inches 30 inches 18 inches 24 inches
30/36 42 inches 30 inches 18 inches 24 inches
42/48/60 42 inches 30 inches 30 inches 24 inches
Table 4a - AVPA Minimum Clearances
MODEL
Min. Clearance
From the Front
Min. Clearance
Around Sides
(Single Unit)
Min. Clearance
Between Sides
(Two Units)
Min. Space
Above Unit
24 42 inches 30 inches 18 inches 24 inches
30/36 42 inches 30 inches 30 inches 24 inches
42/49/60 42 inches 30 inches 30 inches 12 inches
Table 4b - HVPA Minimum Clearances
7. Codes:
Make sure your installation conforms to all applicable electrical, plumbing, building, and municipal
codes. Some codes may limit installation to single story structures.

19 Classic Manual 4/2012 rev. 4
8. Electrical Supply:
The power supply must have the appropriate voltage, phase, and ampacity for the model selected.
Voltage must be maintained above minimum specified values listed below. Refer to the unit data
plate for ampacity requirements.
Electrical Rating Designations* A C D
Nominal Voltage 208/230 208/230 460
Phase 1 3 3
Minimum Voltage 197 197 414
Maximum Voltage 253 253 506
* Letters refer to model number code designations. Refer to page 5.
Table 5 - Voltage Limitations
2.3 Installation Materials
Installation Kits
The Classic Heat Pumps have built-in mounting flanges that function as side brackets. All models
require and are shipped with a bottom mounting bracket. On units with the "N" ventilation option,
there is a fresh air hood factory installed behind the lower front panel.
Standard Kit Components
1. One 12 Ga. “L”-shaped bottom bracket
Accessories:
The package may include other factory-supplied items (optional ) listed on this and the following
page:
PART # DESCRIPTION
50107 Digital thermostat. 2 stage heat, 2 stage cool. 7 day programmable. Fan switch: Auto & On.
Auto-change over. Status LED’s. Backlit display. Programmable fan. Non-volatile program
memory. Title 24 compliant - no batteries needed.
50252 Digital thermostat. 2 stage heat, 2 stage cool. Non-programmable. Fan switch: Auto & On.
Manual or auto changeover system switch: Cool-Off-Heat-Emergency Heat. Status LED’s.
°F or °C. Permanent retention of settings on power loss. Field adjustable temperature
calibration. Adjustable maximum setpoint for heating and minimum adjustable set points
for cooling. Adjustable temperature differential. Keypad lockout.
50248 Digital, 7 day, 2 occupied & 2 unoccupied periods for each day of the week programmable
thermostat. Three stage heat/Three stage cool. Manual or auto changeover. Fan: Auto & On.
Ten year retention of programming settings and 48 hour clock and day settings on power loss.
Adjustable max. setpoint for heating and min. adjustable setpoints for cooling. Adjustable
temperature differential. Keypad lockout. Status LED. °F or °C selectable. Optional remote
sensors for outdoor air, supply air and humidity. Title 24 compliant.

20 Classic Manual 4/2012 rev. 4
PART # DESCRIPTION
50254 Humidity Controller is a wall mounted remote control used when the reheat dehumidification
option is chosen on the Heat Pump. The humidity controller controls the heat pump system
when cooling or heating requirements are satisfied, and the need exists to dehumidify the
conditioned space. When cooling or heating is required the thermostat controls the heat
pump system operation.
50092 Thermostat Guard. For use with the 50107 and the 50252.
Supply Grilles
80674 20" x 8" Adjustable, Aluminum, Double Deflection Supply Grille for AVPA 24
80675 28" x 8" Adjustable, Aluminum, Double Deflection Supply Grille for AVPA 30-36 and
HVPA 24
80676 30" x 10" Adjustable, Aluminum, Double Deflection Supply Grille for AVPA 42-48-60 and
HVPA 30-36-42-49-60
Return Grilles
80677 20" x 12" Aluminum Return Grille for AVPA 24
80678 28" x 14" Aluminum Return Grille for AVPA 30-36 and HVPA 24
80679 30" x 16" Aluminum Return Grille for AVPA 42-48-60 and HVPA 30-36-42-49-60
Return Air Filter Grille
80672 28" x 14" Return Air Filter Grille. Required for use with the AVPA24/30/36 & HVPA24
units with the Greenwheel ERV
Additional Items Needed:
Additional hardware and miscellaneous supplies (not furnished by Marvair®) are needed for installation.
For example, the list below contains approximate quantities of items typically needed for mounting a
unit on a wood frame wall structure with standard full length mounting bracket or flanges. Concrete
or fiberglass structures have different requirements.
(10) 3/8" mounting bolts or lag screws for side brackets and anchors, if required for side brackets.
(20) 3/8" washers
(10) 3/8" hex nuts
(6) 3/8" x 2-1/2" lag screws for bottom bracket
• Silicone Sealer to seal around cracks and openings
• 7-conductor low voltage multi-colored wire cable (i.e. thermostat wire)
• Appropriate electrical supplies such as conduit, electrical boxes, fittings, wire connectors,
etc.
• High voltage wire, sized to handle the MCA (minimum circuit ampacity) listed on the data
plate.
• Over-Current Protection Device sized in accordance with the MFS (maximum fuse size) listed
on the unit data plate.
Duct materials usually are also needed in addition to the mounting hardware. To save time, design
the duct work before mounting the unit.