nate 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. D. The unit shall have two independent refrigerant circuits, equally split in 50% capacity increments.
Unit Controls: A. unit shall be complete with self-contained low-voltage control circuit protected by a resetable circuit breaker on the 24-volt transformer side. B. Unit shall incorpo- rate 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-protection thermostat, evaporator coil.
C. If any of the above safety devices trip, a LED (light-emit- ting diode) indicator shall flash a diagnostic code that indi- cates which safety switch has tripped. D. Unit shall incorporate “AUTO RESET” compressor over temperature, over current protection. E. Unit shall operate with conven- tional thermostat designs and have a low voltage terminal strip for easy hook-up. F. Unit control board shall have on- board diagnostics and fault code display. G. Standard con- trols shall include anti-short cycle and low voltage protection, and permit cooling operation down to 0 °F. H. Control board shall monitor each refrigerant safety switch independently. I. 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 (IF EQUIPPED)
Heat exchanger and exhaust system shall be constructed of aluminized steel or optional stainless steel. 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 (or optional 304 stainless steel) for corrosion resistance and allowing minimum mixed air enter- ing temperature of 40 °F. Burners shall be of the in-shot type, constructed of aluminum-coated steel. All gas piping shall enter the unit cabinet at a single location, 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 pro- vided 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. Unit shall have two independent
stages of capacity (60% 1st stage, 100% 2nd stage).
ELECTRIC HEATING SECTION (IF REQUIRED)
An electric heating section, with nickel chromium elements, shall be provided in a range of 9 thru 54 KW, offering two stages of capacity all sizes. The heating section shall have a primary limit control(s) (automatic reset) to prevent the heat- ing element system from operating at an excessive tempera- ture. 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).
036-21484-001-B-0103
UNIT OPERATING CHARACTERISTICS
Unit shall be capable of starting and running at 125 °F out- door 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 tempera- ture. 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):
1.ELECTRONIC ENTHALPY AUTOMATIC ECONO- MIZER – Outdoor and return air dampers that are inter- locked and positioned by a fully-modulating, spring- return damper actuator. The maximum leakage rate for the outdoor air intake dampers shall not exceed 2% when dampers are fully closed and operating against a pressure differential of 0.5 IWG. A unit-mounted potenti- ometer shall be provided to adjust the outdoor and return air damper assembly to take in outdoor air to meet the minimum ventilation requirement of the conditioned space during normal operation. During economizer oper- ation, 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 con- trol 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 or power exhaust.
2.MOTORIZED OUTDOOR AIR DAMPERS – Outdoor and return air dampers that are interlocked and positioned by a 2-position, spring-return damper actuator. The maxi- mum leakage rate for the outdoor air intake dampers shall not exceed 2% when dampers are fully closed and operating against a pressure differential of 0.5 IWG. A unit-mounted potentiometer shall be provided to adjust the outdoor and return air damper assembly to take in
