Instruction manual
© 2014 Pentair Equipment Protection
89074139
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TECHNICAL INFORMATION
SEQUENCE OF OPERATION
The air conditioner comes standard with two internally mounted thermostats or remote access control. There
are two modes of operation; heating and cooling. During heating and cooling modes the evaporator fan will be
running.
HEATING
When the enclosure temperature is below the heating thermostat setpoint, power is applied to the
heaters. When the enclosure temperature is 10 degrees above the setpoint the heater is powered off.
COOLING
When the enclosure temperature is above the cooling thermostat setpoint, power is applied through the
thermostat. The compressor is then energized either directly or through a contactor if unit requires one.
The condenser impellers will start immediately if the unit is not equipped with an optional head pressure
control switch. If the unit is equipped with an optional head pressure control switch, the condenser
impellers will start once the refrigerant pressure reaches the setting of the switch. Component specific
information is listed below.
Operating the air conditioner below the minimum ambient temperature or above the maximum ambient
temperatures indicated on the nameplate voids all warranties. DO NOT set the enclosure thermostat to a
temperature lower than 70 F. Doing so can increase the likelihood of frost buildup on the evaporator coil.
The moisture that the enclosure air can contain is limited. If moisture flows from the drain tube
continuously this can only mean that ambient air is entering the enclosure. Be aware that frequent
opening of the enclosure’s door admits humid air that the air conditioner must then dehumidify.
STANDARD AND OPTIONAL COMPONENT OPERATION
THERMOSTAT
The standard G28 air conditioner uses our standard 10-1061-16 thermostat. The thermostat setpoint
equals the temperature that the air conditioner turns off. The thermostat has a 10 F differential from
setpoint until it calls for cooling or heating. An example of operation is shown below.
FOR COOLING (75100 F RANGE):
• Thermostat setpoint = 80 F
• Cooling turns on at 90 F
• Cooling turns off at 80 F
FOR HEATING (5565 F RANGE):
• Thermostat setpoint = 55 F
• Heating turns on at 55 F
• Heating turns off at 65 F
NOTE: For testing purposes only, the thermostat stop screw may be removed (on units so
equipped) to allow settings below 70 F. After testing, replace the stop screw and verify that
the thermostat cannot be set below 70 F. Extended operation below 70 F can cause coil freeze
ups resulting in reduced load and/or unit damage.
REMOTE ACCESS CONTROL (OPTIONAL)
See REMOTE ACCESS CONTROL (optional) on page 12
HEAD PRESSURE CONTROL (OPTIONAL)
Unit is set at the factory, no adjustment necessary.
At a saturated condenser temperature of 82 F (95 psig), the condenser fans will power off. At a saturated
condenser temperature of 105 F (165 psig), the condenser fans will power on.
200V TO 230V TRANSFORMER (N280425GXXX ONLY)
The 230V from this transformer powers the compressor only.
115V/230V TO 10V TRANSFORMER (OPTIONAL)
This transformer powers the thermal display on thermostat controlled units only.
115V/230V TO 24V TRANSFORMER AND RELAY (OPTIONAL)
The transformer and relay are used to operate the condenser blower and compressor by using a customer
supplied, remote mounted door switch. This is not a safety door switch, but rather, only helps to reduce
condensation at the evaporator coil if the door is opened. The unit will remain electrified when the door
switch is operated with the evaporator fan continuing to operate, and potentially, if temperatures are low
enough, the heater may continue to operate on outdoor models.