Features

All Series 20 J**DJ models are available with a wide variety of factory-mounted options such as stainless steel heat exchangers, phase monitor, dirty filter switch, and coil guard to make them suitable for almost every application.

All units are self-contained and assembled on full perimeter base rails with holes in the four corners for overhead rigging. Every unit is completely piped, wired, charged and tested at the factory to simplify the field installation and to provide years of dependable operation.

All models (including those with an economizer) are suitable for either bottom or horizontal duct connections. Models with factory installed power exhaust are suitable for bottom duct connections only. For bottom duct, you remove the sheet metal panels from the supply and return air openings through the base of the unit. For horizontal duct, you replace the supply and return air panels on the rear of the unit with a side duct flange accessory.

All models are available with these “factory mounted” outdoor air damper options:

•Single enthalpy economizer with or without power exhaust

•BAS-ready economizer with or without power exhaust

•Motorized outdoor air damper

•Barometric Relief Damper

A fixed outdoor air intake assembly will be shipped in the return air compartment of all units ordered without an econo- mizer or motorized outdoor air damper option. The assembly includes a rain hood with a damper that can be set for 10, 15 or 25% outdoor air. With bottom duct connections, the intake damper assembly should be mounted over the opening in the return air panel. With horizontal ductwork, it should be mounted on the return air duct.

All supply air blowers are equipped with a belt drive that can be adjusted to meet the exact requirements of the job. A high static drive option is available for applications with a higher CFM and/or static pressure requirement. A variable air vol- ume (VAV) option using a variable frequency drive is available for applications requiring a constant supply duct pressure. A differential pressure transducer is used to monitor supply duct static pressure and return a speed reference signal to the VFD to control the output of the indoor blower motor.

All compressors include scroll compressors and internal pres- sure relief. Every refrigerant circuit includes an expansion valve, a liquid line filter-drier, a discharge line high pressure switch and a suction line with a freezestat and low pressure/ loss of charge switch to protect all system components. A hot gas bypass option, consisting of an adjustable compressor discharge bypass valve, is available for low cooling load applications.

•Advanced Controls - Unit control boards have stan- dardized a number of features previously available only as options or by utilizing additional controls.

349687-JTG-A-1007

•Low Ambient - An integrated low-ambient control allows all units to operate in the cooling mode down to 0ºF outdoor ambient without additional assis- tance. Optionally, the control board can be pro- grammed to lockout the compressors when the outdoor air temperature is low or when free cooling is available.

•Anti-Short Cycle Protection - To aid compressor life, an anti-short cycle delay is incorporated into the standard controls. Compressor reliability is further ensured by programmable minimum run times. For testing, the anti short cycle delay can be temporarily overridden with the push of a button.

•Lead-Lag- An integrated Lead-Lag option allows equal run time hours on all compressors, thereby extending the life of all compressors. This option is selectable on the unit control board.

•Fan Delays - Fan on and fan off delays are fully pro- grammable. Furthermore, the heating and cooling fan delay times are independent of one another. All units are programmed with default values based upon their configuration of cooling and heat.

•Safety Monitoring - The control board monitors the high and low-pressure switches, the freezestats, the gas valve, if applicable, and the temperature limit switch on gas and electric heat units. The unit con- trol board will alarm on ignition failures, compressor lockouts and repeated limit switch trips.

•Nuisance Trip Protection and Strikes - To prevent nuisance trouble calls, the control board uses a “three times, you’re out” philosophy. The high and low-pressure switches and the freezestats must trip three times within two hours before the unit control board will lock out the associated compressor.

•On Board Diagnostics - Each alarm will energize a trouble light on the thermostat, if so equipped, and flash an alarm code on the control board LED. Each high and low-pressure switch alarm as well as each freezestat alarm has its own flash code. The control board saves the five most recent alarms in memory, and these alarms can be reviewed at any time. Alarms and programmed values are retained through the loss of power.

All units have long lasting powder paint cabinets with 750 hour salt spray test approval under ASTM-B117 procedures.

All models are CSA approved.

•Warranty - All models include a one-year limited parts warranty on the complete unit. Compressors and electric heater elements carry a five-year warranty. Gas heat exchangers carry a 10-year parts warranty.

•Gas Heat Operation - All gas heat units are built with two heating sections for two equal stages of capacity control. Each section includes a durable heat exchanger

4	Johnson Controls Unitary Products