Technical Guide
528150-YTG-T-0514
14 Johnson Controls Unitary Products
be of the tubular type, constructed of T1-40 aluminized steel for
corrosion resistance and allowing minimum mixed air entering
temperature of 40 ºF. Burners shall be of the in-shot type, con-
structed of aluminum-coated steel. All gas piping shall enter the
unit cabinet at a single location, through either the side or bot-
tom, without any field modifications. An integrated control board
shall provide timed control of evaporator fan functioning and
burner ignition. Heating section shall be provided with the fol-
lowing minimum protection:
a. Primary and auxiliary high-temperature limit switches.
b. Induced draft pressure sensor.
c. Flame roll out switch (manual reset).
d. Flame proving controls.
e. All two stage gas units shall have two independent
stages of capacity (70% or 75% 1st stage, 100% 2nd
stage) 3 through 5 ton and (60% 1st stage, 100% 2nd
stage) 6-1/2 through 12-1/2 ton.
ELECTRIC HEATING SECTION (IF EQUIPPED)
An electric heating section, with nickel chromium elements,
shall be provided in a range of 3 thru 54KW. The heating sec-
tion shall have a primary limit control(s) (automatic reset) to pre-
vent the heating element system from operating at an
excessive temperature. The Heating Section assembly shall
slide out of the unit for easy maintenance and service. Units
with Electric Heating Sections shall be wired for a single point
power supply with branch circuit fusing (where required).
UNIT OPERATING CHARACTERISTICS
Unit shall be capable of starting and running at 125 ºF outdoor
temperature, exceeding maximum load criteria of AHRI Stan-
dard 340/360. The compressor, with standard controls, shall be
capable of operation down to 0 ºF outdoor temperature. Unit
shall be provided with fan time delay to prevent cold air delivery
before heat exchanger warms up. (Gas heat only)
ELECTRICAL REQUIREMENTS - All unit power wiring shall
enter unit cabinet at a single factory provided location and be
capable of side or bottom entry to minimize roof penetrations
and avoid unit field modifications. Separate side and bottom
openings shall be provided for the control wiring.
STANDARD LIMITED WARRANTIES - Compressor – 5 Years,
Heat Exchanger – 10 Years, Elect. Heat Elem. – 5 Years,
Parts – 1 Year
OPTIONAL OUTDOOR AIR (Shall be made available by either/
or):
• ELECTRONIC ENTHALPY AUTOMATIC ECONOMIZER
- Outdoor and return air dampers that are interlocked and
positioned by a fully-modulating, spring-return damper
actuator. The maximum leakage rate for the outdoor air
intake dampers shall be designed to meet ASHRAE 90.1-
2010, AMCA 511 Class 1A damper, and the International
Energy Conservation Code (IECC) certification
requirements by achieving leakage rates of 3 cfm/sq. ft. at
1" of static pressure. During economizer operation, a
mixed-air temperature control shall modulate the outdoor
and return air damper assembly to prevent the supply air
temperature from dropping below 55°F. Changeover from
compressor to economizer operation shall be provided by
an integral electronic enthalpy control that feeds input into
the basic module. The outdoor intake opening shall be
covered with a rain hood that matches the exterior of the
unit. Water eliminator/filters shall be provided.
Simultaneous economizer/compressor operation is also
possible. Dampers shall fully close on power loss.
Available with barometric relief and power exhaust.
• MOTORIZED OUTDOOR AIR DAMPERS - Outdoor and
return air dampers that are interlocked and positioned by
a 2- position, spring-return damper actuator. A unit-
mounted potentiometer shall be provided to adjust the
outdoor and return air damper assembly to take in the
design CFM of outdoor air to meet the ventilation
requirements of the conditioned space during normal
operation. Whenever the indoor fan motor is energized,
the dampers open up to one of two pre-selected positions
- regardless of the outdoor air enthalpy. Dampers return to
the fully closed position when the indoor fan motor is de-
energized. Dampers shall fully close on power loss.
ADDITIONAL FACTORY INSTALLED OPTIONS
• ALTERNATE INDOOR BLOWER MOTOR – For
applications with high restrictions, units are available with
optional indoor blower motors that provide higher static
output and/or higher airflow.
• VARIABLE AIR VOLUME (VAV) - The VAV option using
a variable frequency drive (VFD) shall be available on
6-1/2 through 12-1/2 ton models for applications requiring
a constant supply-duct static pressure. Units equipped for
VAV shall be controlled by a duct pressure transducer
with a 0 - 5" WC pressure range. The pressure transducer
shall provide a 0 - 5 VDC output signal to a VAV control
board which, in turn shall provide a 2 - 10 VDC speed
reference signal to the VFD. The VAV control board shall
operate using factory-installed Supply Air, Return Air and
Outside Air Temperature Sensors with a nominal
resistance of 10,000 Ohms. Units equipped with VFD's
shall have factory-installed manual bypass as an option.
• CONVENIENCE OUTLET (POWERED/NON-POWERED)–
Unit can be provided with an optional 120VAC GFCI outlet
with cover on the corner of the unit housing the compressors.
• ELECTRIC HEAT - Electric Heaters range from 3kW to
54kW and are available in all the voltage options of the
base unit.
• PHASE MONITOR - Designed to prevent damage in out-
of-phase condition.
• COIL GUARD - Designed to prevent condenser coil
damage.
• BAS CONTROLS - Include supply air sensor, return air
sensor, dirty filter indicator and air proving switch.
• DIRTY FILTER SWITCH – This kit includes a differential
pressure switch that energizes the fault light on the unit