262260-YTG-E-1008
4
Johnson Controls Unitary Products
FEATURES
All models are available with a wide variety of factory-
mounted options such as stainless steel heat exchangers,
phase monitor, dirty filter switch, and coil guard to make them
suitable for almost every application.
All units are self-contained and assembled on full perimeter
base rails with holes in the four corners for overhead rigging.
Every unit is completely piped, wired, charged and tested at
the factory to simplify the field installation and to provide
years of dependable operation.
All models (including those with an economizer) are suitable
for either bottom or horizontal duct connections.
Models with
factory installed power exhaust are suitable for bottom
duct connections only
. For bottom duct, you remove the
sheet metal panels from the supply and return air openings
through the base of the unit. For horizontal duct, you replace
the supply and return air panels on the rear of the unit with a
side duct flange accessory.
All models are available with these “factory mounted” outdoor
air damper options:
•
Single enthalpy economizer with or without power
exhaust
•
BAS-ready economizer with or without power exhaust
•
Motorized outdoor air damper
•
Barometric Relief Damper
A fixed outdoor air intake assembly will be shipped in the
return air compartment of all units ordered without an econo-
mizer or motorized outdoor air damper option. The assembly
includes a rain hood with a damper that can be set for 10, 15
or 25% outdoor air. With bottom duct connections, the intake
damper assembly should be mounted over the opening in the
return air panel. With horizontal ductwork, it should be
mounted on the return air duct.
All supply air blowers are equipped with a belt drive that can
be adjusted to meet the exact requirements of the job. A high
static drive option is available for applications with a higher
CFM and/or static pressure requirement. A variable air volume
(VAV) option using a variable frequency drive is available for
applications requiring a constant supply duct pressure. A dif-
ferential pressure transducer is used to monitor supply duct
static pressure and return a speed reference signal to the VFD
to control the output of the indoor blower motor.
All compressors include scroll compressors and internal pres-
sure relief. Every refrigerant circuit includes an expansion
valve, a liquid line filter-drier, a discharge line high pressure
switch and a suction line with a freezestat and low pressure/
loss of charge switch to protect all system components. A hot
gas bypass option, consisting of an adjustable compressor
discharge bypass valve, is available for low cooling load
applications.
•
Simplicity
®
Controls
-
Simplicity
®
control boards have
standardized a number of features previously available
only as options or by utilizing additional controls.
•
Low Ambient
- An integrated low-ambient control
allows all units to operate in the cooling mode down
to 0°F outdoor ambient without additional assis-
tance. Optionally, the control board can be pro-
grammed to lockout the compressors when the
outdoor air temperature is low or when free cooling
is available.
•
•
Anti-Short Cycle Protection
- To aid compressor
life, an anti-short cycle delay is incorporated into the
standard controls. Compressor reliability is further
ensured by programmable minimum run times. For
testing, the anti short cycle delay can be temporarily
overridden with the push of a button.
•
Lead-Lag
- An integrated Lead-Lag option allows
equal run time hours on all compressors, thereby
extending the life of all compressors. This option is
selectable on the unit control board.
•
Fan Delays
- Fan on and fan off delays are fully pro-
grammable. Furthermore, the heating and cooling
fan delay times are independent of one another. All
units are programmed with default values based
upon their configuration of cooling and heat.
•
Safety Monitoring
- The control board monitors the
high and low-pressure switches, the freezestats, the
gas valve, if applicable, and the temperature limit
switch on gas and electric heat units. The unit con-
trol board will alarm on ignition failures, compressor
lockouts and repeated limit switch trips.
•
Nuisance Trip Protection and Strikes
- To prevent
nuisance trouble calls, the control board uses a
“three times, you’re out” philosophy. The high and
low-pressure switches and the freezestats must trip
three times within two hours before the unit control
board will lock out the associated compressor.
•
On Board Diagnostics
- Each alarm will energize a
trouble light on the thermostat, if so equipped, and
flash an alarm code on the control board LED. Each
high and low-pressure switch alarm as well as each
freezestat alarm has its own flash code. The control
board saves the five most recent alarms in memory,
and these alarms can be reviewed at any time.
Alarms and programmed values are retained
through the loss of power.
The
Simplicity
® control board used in this product will
effectively operate the cooling system down to 0°F
when this product is applied in a comfort cooling
application for people. An economizer is typically
included in this type of application. When applying this
product for process cooling applications (computer
rooms, switchgear, etc.), please reference applications
bulletin AE-011-07 or call the applications department
for Unitary Products @ 1-877-UPG-SERV for
guidance. Additional accessories may be needed for
stable operation at temperatures below 30°F.
