York Predator ZT037 Technical Manual page 12

5167821-YTG-J-0518
Unit Controls:
a. Unit shall be complete with self-contained low-voltage
control circuit protected by a resettable circuit breaker on
the 24-volt transformer side.
b. Unit shall incorporate a lockout circuit which provides
reset capability at the space thermostat or base unit,
should any of the following standard safety devices trip
and shut off compressor.
1. Loss-of-charge/Low-pressure switch.
2. High-pressure switch.
3. Freeze condition sensor on evaporator coil. If any of
these safety devices trip, the LCD screen will display
the alarm message.
c. Unit shall incorporate "AUTO RESET" compressor over
temperature, over current protection.
d. Unit shall operate with conventional thermostat designs
and have a low voltage terminal strip for easy hook-up.
e. Unit control board shall have on-board diagnostics and
fault message display.
f. Standard controls shall include anti-short cycle and low
voltage protection, and permit cooling operation down to
a selectable value as low as 0 °F.
g. Control board shall monitor each refrigerant safety switch
independently.
GAS HEATING SECTION (IF EQUIPPED)
Heat exchanger and exhaust system shall be constructed of
aluminized steel and shall be designed with induced draft com-
bustion with post purge logic, energy saving direct spark igni-
tion, and redundant main gas valve. The heat exchanger shall
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).
ELECTRIC HEATING SECTION (IF EQUIPPED)
An electric heating section, with nickel chromium elements,
shall be provided in a range of 3 thru 24KW. The heating sec-
tion shall have a primary limit control(s) (automatic reset) to pre-
vent the heating element system from operating at an
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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
FACTORY INSTALLED OPTIONAL OUTDOOR AIR (Shall be
made available by either/or):
• DRY BULB 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, 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. 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
Johnson Controls Ducted Systems