Specifications

AVPA & HVEA PDS 1/2012 rev.1 2
A Marvair
®
First – Factory Installed Economizer
Marvair’s ComPac
®
II air conditioner has been the industry standard since its introduction in 1986. Tens of
thousands of ComPac II air conditioners are in operation from the metropolitan areas of North America to the
deserts of the Mid-East to the Siberian tundra. Here’s how the economizer works:
On a signal from the wall mounted indoor thermostat that cooling is required, either mechanical cooling
with the compressor or free cooling with the economizer is provided. A factory installed enthalpy controller
determines whether the outside air is sufficiently cool and dry to be used for cooling. If suitable, the
compressor is locked out and the economizer damper opens to bring in outside air. Integral pressure relief
allows the interior air to exit the shelter, permitting outside air to enter the shelter. The temperature at
which the economizer opens is adjustable from 53°F (12°C) at 50% Relative Humidity to 78°F (26°C) at 50%
Relative Humidity.
After the enthalpy control has activated and outside air is being brought into the building, the mixed air
sensor measures the temperature of the air entering the indoor blower and then modulates the economizer
damper to mix the right proportion of cool outside air with warm indoor air to maintain 50-56°F (10 - 13°C)
air being delivered to the building. This prevents shocking the electronic components with cold outside air.
The compressor is not permitted to operate when the economizer is functioning.
If the outside air becomes too hot or humid, the economizer damper closes completely, or to a minimum
open position with an optional minimum position potentiometer, and mechanical cooling is activated.
Unlike other economizers, the Marvair 100% economizer cycle provides the same quantity of outside air
(CFM) as is provided in mechanical cooling (compressor operation). The 100% economizer increases the
savings by taking full advantage of using outside air to cool the shelter.
Standard Features
Designed for Operation in Low
Ambient Conditions
• Lowambientcontrolcycles
condenser fan to maintain proper
refrigerant pressures. Allows
operation in mechanical cooling
(compressor) down to 0ºF
(-18ºC). Note: low temperature
operation is affected by ambient
conditions, e.g. wind and humidity.
• Threeminuteby-passofthe
low pressure switch for start-
up of compressor when outdoor
temperatures are below 55°F
(13°C).
• Factorybuilt-ineconomizer.*
High Efficiency
• Highefficiencycompressor.
• Lancedfinsandrifledtubingon
many condenser & evaporator
coils.
Built-in Reliability
• Highpressureswitchandlow
pressure switch with lockout
protects refrigerant circuit.
• Threeminutedelayonmakefor
short cycle protection.
Remote Alarm Capability
• Drycontactscanbeusedfor
remote alarm or notification upon
air conditioner lockout.
Ease of Installation
• Slopedtopwithflashingeliminates
need of rainhood.
• Built-inmountingflangesfacilitate
installation and minimize chance
of water leaks.
• Supplyandreturnopenings
exactly match previous models.
• Factoryinstalleddisconnectonall
units.
Rugged Construction
• Coppertube,aluminumfin
evaporator & condenser coils.
• Factoryinstalledheaterson
discharge side of evaporator coil
(optional)
• Bakedonneutralbeigefinishover
galvanneal steel for maximum
cabinet life. (Other finishes are
available.)
Ease of Service
• Serviceaccessvalvesare
standard.
• Standard2”(50mm)pleated
filter with a MERV rating of 7
changeable from outside.
• Allmajorcomponentsarereadily
accessible.
• FrontControlPanelallowseasy
access and complies with NEC
clearance codes on redundant
side-by-side systems.
• LEDsindicateoperationalstatus
and fault conditions.
*ComPac
®
II air conditioner only
33