Refrigerant Circuit And Refrigerant Safety Components Shall Include; Unit Controls; Gas Heating Section; Electric Heating Section - York ZT SERIES Technical Manual

Refrigerant Circuit and Refrigerant Safety Components shall include:

a. Independent fixed-orifice or thermally operated expansion devices.
b. Solid core filter drier/strainer to eliminate any moisture or foreign matter.
c. Accessible service gage connections on both suction and discharge lines to charge, evacuate, and measure refrigerant
pressure during any necessary servicing or troubleshooting, without losing charge.

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 combustion
with post purge logic, energy saving direct spark ignition, 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, constructed of aluminum-coated steel. All gas piping shall enter the unit cabinet at a single loca-
tion, through either the side or bottom, 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 following 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 through 54KW. The heating section
shall have a primary limit control(s) (automatic reset) to prevent the heating element system from operating at an excessive tem-
perature. The Heating Section assembly shall slide out of the unit for easy maintenance and service. Units with Electric Heating Sec-
tions 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 Standard 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):
Johnson Controls Ducted Systems
5167821-YTG-K-1118
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