York ZR Series Installation Manual

Also see for ZR SERIES: Technical guide Wiring diagrams Installation manual

Contents

275864-YIM-F-021328 Johnson Controls Unitary Products• RH - a 0-10 VDC analog input provided by a field-installedreturn air relative humidity sensor for dual enthalpyeconomizer configuration (used with OH).• IAQ - a 0-10 VDC analog input provided by a field-installedcarbon dioxide sensor which monitors indoor air quality(CO2 concentration) and enables call for DemandVentilation mode for units installed with economizer option.• OAQ - a 0-10 VDC analog input provided by a field-installed carbon dioxide sensor which monitors outdoor airquality (CO2 concentration) and, along with IAQ, enablescall for Differential Demand Ventilation mode for unitsinstalled with economizer option.• APS - a 24 VAC binary input provided by a field-installedair proving switch which monitors the pressure differenceacross the indoor blower.• PUR - a 24 VAC binary input for building purge calls froman external source.• OCC - a 24 VAC binary input used to set the buildingoccupancy status for the control.• LIMIT 2 - a 24 VAC binary input which either confirms2nd-stage gas heat operation or receives an error signalfrom the variable frequency drive.Outputs:• FAN - a 2-10 VDC analog output signal sent to the VFD tomodulate the speed of the indoor blower motor.• ECON - a 2-10 VDC analog output signal sent to theeconomizer actuator to modulate position of the return airand outdoor air dampers (optional).• EXH ~ - a 24 VAC binary output signal used to turn on/offthe power exhaust relay (optional).• VAV BOX (gas/electric heat only) - a normally openrelay contact connected to a terminal block, used todrive the building's VAV boxes to full-open during heatingoperation.Programmable set points:The duct static set point is the pressure that the drive willmaintain when operating the unit in VAV mode. The set-point isadjustable between 0" WC and 5" WC with the default setting of1.5" WC.The duct static high-limit set point is the maximum allowableduct pressure to prevent damage from over-pressurization ofthe ductwork in the event of either a drive or damper failure.The high-limit set-point is adjustable between 0" WC and 5" WCwith the factory default setting of 4.5" WC. If the duct staticpressure reaches the high-limit set point, then the supply fanmotor will be shutdown.NOTE: Either of the set points described above can bechanged through the unit control board (UCB) with theuse of a USB-to-RS485 converter, personal computeror PDA and a down-loaded copy of the Simplicity®software available at the UPGnet Commercial ProductCatalog website.Factory-installed VFDThe factory-installed VFD is mounted in the Blower AccessCompartment above the blower assembly. The drive comeswired from the factory to include both 3-phase power andcontrol connections (run permit signal, speed reference signal &fault signal).All required drive parameters are pre-programmed at the factory,except in the case of 208-volt applications, in which theparameter that defines motor nameplate voltage must bechanged to a value of 208.00 and the parameter that definesmotor-rated current must be changed to the appropriate valueappearing on the motor's nameplate. Refer to the enclosed drivematerial or access the UPGnet Commercial Product Catalogwebsite for instructions on changing parameter settings.For units also equipped with gas/electric heat, a terminalblock located in the unit's control box and connected tothe VAV board's "VAV BOX" terminal, must be field wiredto the building's VAV boxes to ensure fully open dampersduring heating operation.Manual BypassAn optional, factory-installed manual bypass switch availablewith factory-installed VFD can be found in the Blower MotorAccess compartment and has the following three positions:• DRIVE - routes power through the VFD for modulatingcontrol of the indoor blower motor.• LINE (or BYPASS) - routes power directly to the motorwhich provides full-speed motor operation and completeelectrical isolation of the drive.• TEST - routes power to the VFD but not to the motor toallow for drive programming and/or diagnostics.If a drive failure occurs, the unit does not automatically switch tobypass mode. The LINE/DRIVE/TEST switch must be manuallyswitched to the LINE (BYPASS) position. If there is a call for thefan, the indoor blower motor will run at full-speed while in thebypass mode.The customer must be aware of the duct pressuredesign limit, and what the duct pressure sensor isreading when the peak pressure is reached (i.e. thepressure transducer sensing tube may not be located atthe place of highest pressure in the system).