York ECO R-407C User Manual

YORK INTERNATIONAL26ControlsGENERALThe control system for the YORK eco 2 Packaged Roof-top Unit is fully self-contained and based around anOptiLogic™ rooftop unit controller. To aid in unit setup,maintenance, and operation, the OptiLogic™ rooftopunit controller is equipped with a user interface that isbased around a 4 line x 20 character backlit LCD dis-play. The LCD displays plain language text in a menu-driven format to facilitate use. In addition to the display,the OptiLogic™ user interface is also equipped with anLED indicator light, which will warn of any abnormaloperation of the equipment or communication failures.For the maximum in system flexibility, the YORK ECO 2Packaged Rooftop Unit can be operated by either atypical 7-wire thermostat (2 cool / 2 heat), a space tem-perature sensor, or stand-alone (VAV only). Note, a fieldwiring terminal block is provided to facilitate unit setupand installation.In lieu of the hard-wired control options, the OptiLogic™rooftop unit controller can be connected to and oper-ated by a Building Automation System (BAS). If re-quired, the OptiLogic™ rooftop unit controller can beequipped with an optional BACNet IP communicationcard, which allows communication, via Ethernet, to aBACNet IP based BAS.UNOCCUPIED / OCCUPIED SWITCHINGDepending on application, the unit can be indexed be-tween unoccupied and occupied modes of operationby one of three methods, hard-wired input, internal timeclock, or BAS. A contact-closure input is provided forhard-wiring to an external indexing device such as acentral time clock, thermostat with built in scheduling,or a manual switch. The unit controller is also equippedwith a built in 7-day time clock which can be used, inlieu of the contact closure input, to switch the unit be-tween Unoccupied and Occupied modes of operation.The internal time clock is fully configurable via the userinterface and includes Holiday scheduling. In additionto the hard-wired input or the internal time clock, theunit can also be indexed between unoccupied and oc-cupied modes of operation via a BAS command.Note a unit operated from a space sensor can beequipped to temporarily override an unoccupied modeof operation. This Unoccupied Override feature is fullyconfigurable via the OptiLogic™ user interface.ECONOMIZER OPERATIONThe unit can be equipped with one of three types ofoptional economizers, dry bulb, single enthalpy, or com-parative enthalpy. When the unit controller determinesthat Outside Air is suitable for economizing, the unitcontroller will control the outside air damper(s) open toprovide economizer cooling. If economizer cooling aloneis insufficient for the cooling load, the unit controllershall stage up compressors, one at a time, to meetdemand.The control logic for the three types of economizers isas follows:Dry Bulb EconomizerThe dry bulb economizer is the default economizer con-trol scheme. With the dry bulb economizer, the unit con-troller monitors the Outside Air temperature only andcompares it to a reference temperature setting. OutsideAir is deemed suitable for economizing when the Out-side Air temperature is determined to be less than thereference temperature setting. This method of econo-mizing is effective, but is prone to some changeover in-efficiencies due to the fact that this method is based onsensible temperatures only and does not take OutsideAir moisture content into consideration.Single Enthalpy EconomizerWith the optional single enthalpy economizer, the unitcontroller monitors the Outside Air enthalpy in additionto the Outside Air temperature and compares it to areference enthalpy setting and a reference tempera-ture setting. Outside Air is deemed suitable for econo-mizing when the Outside Air enthalpy is determined tobe less than the reference enthalpy setting and the Out-side Air temperature is less than the reference tem-perature setting. This method of economizing allowsthe reference temperature setting to be set higher thanthe DB Economizer and is consequently a more effi-cient packaged rooftop economizer.Comparative Enthalpy EconomizerWith the optional comparative enthalpy economizer, theunit controller monitors and compares the Outside Airand Return Air enthalpies in addition to comparing theOutside Air temperature to the reference temperaturesetting. Outside Air is deemed suitable for economiz-ing when the Outside Air enthalpy is determined to beCONTROL SEQUENCES FOR ALL UNITS