251933-YTG-B-0806
Unitary Products Group 9
enhanced copper tubes with all joints brazed. Special
Phenolic coating shall be available as a factory option.
b. Evaporator and Condenser coils shall be of the direct
expansion, draw-thru, design.
Refrigerant Circuit and Refrigerant Safety Components shall
include:
a. Independent fixed-orifice or thermally operated
expansion devices.
b. Filter drier/strainer to eliminate any moisture or foreign
matter.
c. Accessible service gage connections on both suction
and liquid lines to charge, evacuate, and measure
refrigerant pressure during any necessary servicing or
troubleshooting, without losing charge.
d. The refrigeration system shall provide at least 15°F of
sub-cooling at design conditions.
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.
c. Loss-of-charge/Low-pressure switch.
d. High-pressure switch.
e. Freeze-protection thermostat, evaporator coil.
f. Unit shall incorporate “AUTO RESET” compressor over
temperature, over current protection.
g. Unit shall operate with conventional thermostat designs
and have a low voltage terminal strip for easy hook-up.
h. Unit control board shall have on-board diagnostics and
fault code display.
i. Standard controls shall include anti-short cycle and low
voltage protection, and permit cooling operation down to
0°F.
j. Control board shall monitor each refrigerant safety switch
independently.
k. Control board shall retain last 5 fault codes in non volatile
memory which will not be lost in the event of a power loss.
Gas Heating Section (Single Or 2 Stage)
Shall be designed with induced draft combustion with post
purge logic, energy saving direct spark ignition, and redundant
main gas valve. Venter wheel shall be constructed of stainless
steel for corrosion resistance. 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 25°F. Burners shall be of the inshot type,
constructed of aluminum coated steel and contain air mixture
adjustments. All gas piping shall enter the unit cabinet at a
single location through either the side or curb without any field
modifications. Integrated control boards 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 motor speed sensor.
c. Flame roll out switch.
d. Flame proving controls.
e. If any of the above safety devices trip, a LED (light-
emitting diode) indicator shall flash a diagnostic code that
indicates which safety switch has tripped.
Electric Heating Section
An electric heating section, with nickel chromium elements,
shall be provided in a range of 5 thru 30 KW, offering two
stages of capacity - 16 KW and above on 208/230 volt heaters
and 20 KW and above on 460 and 575 volt heaters. The
heating section shall have a primary limit control(s) and
automatic reset to prevent 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 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°F outdoor
temperature, exceeding maximum load criteria of ARI Standard
210/240. The compressor, with standard controls, shall be
capable of operation down to 0°F 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
• Electric Heat Element 5 Years
• Other 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
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