Unit Controls

036-21502-002-A-0303

internally 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 expansion devices.

b.Filter drier/strainer to eliminate any moisture or for- eign matter.

c.Accessible service gage connections on both suc- tion and liquid lines to charge, evacuate, and mea- sure 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.

a.Unit shall be complete with self-contained low-volt- age control circuit protected by a resetable circuit breaker on the 24-volt transformer side.

b.Unit shall incorporate a lockout circuit which pro- vides 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.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.

g.Unit shall incorporate “AUTO RESET” compressor over temperature, over current protection.

h.Unit shall operate with conventional thermostat designs and have a low voltage terminal strip for easy hook-up.

i.Unit control board shall have on-board diagnostics and fault code display.

j.Standard controls shall include anti-short cycle and low voltage protection, and permit cooling operation down to 0°F.

k.Control board shall monitor each refrigerant safety switch independently.

l.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

Shall be designed with induced draft combustion with post purge logic, energy saving direct spark ignition, and redun-

dant 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 con- tain 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. 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 motor speed sensor.

c.Flame roll out switch (manual reset).

d.Flame proving controls.

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 heat- ers and 20 KW and above on 460 and 575 volt heaters. The heating section shall have a primary limit control(s) and auto- matic reset to prevent the heating element system from oper- ating 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

a.Unit shall be capable of starting and running at

125°F outdoor temperature, exceeding maximum load criteria of ARI Standard 210/240. The compres- sor, with standard controls, shall be capable of oper- ation 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

Unitary Products Group