Bard W18HB-A Installation Instructions Manual

Also see for W18HB-A: Installation instructions

Manual 2100-703Page 21 of 40High and Low Pressure SwitchAll W**H Series wall-mounted heat pump modelsare supplied with a remote reset for the high and lowpressure switch. If tripped, this pressure switch may bereset by turning the thermostat off then back on again.Three Phase Scroll Compressor StartUp InformationScroll compressors, like several other types ofcompressors, will only compress in one rotationaldirection. Direction of rotation is not an issue withsingle phase compressors since they will always startand run in the proper direction.However, three phase compressors will rotate in eitherdirection depending upon phasing of the power.Since there is a 50-50 chance of connecting powerin such a way as to cause rotation in the reversedirection, verification of proper rotation must be made.Verification of proper rotation direction is made byobserving that suction pressure drops and dischargepressure rises when the compressor is energized.Reverse rotation also results in an elevated sound levelover that with correct rotation, as well as substantiallyreduced current draw compared to tabulated values.Verification of proper rotation must be made at the timethe equipment is put into service. If improper rotationis corrected at this time, there will be no negativeimpact on the durability of the compressor. However,reverse operation for over 1 hour may have a negativeimpact on the bearing due to oil pump out.NOTE: If compressor is allowed to run in reverserotation for several minutes, the compressor’sinternal protector will trip.All three phase ZP compressors are wired identicallyinternally. As a result, once the correct phasing isdetermined for a specific system or installation,connecting properly phased power leads to the sameFusite terminal should maintain proper rotationdirection.The direction of rotation of the compressor may bechanged by reversing any two line connections to theunit.Phase MonitorAll units with three phase scroll compressors areequipped with a three phase line monitor to preventcompressor damage due to phase reversal.The phase monitor in this unit is equipped with twoLEDs. If the Y signal is present at the phase monitorand phases are correct, the green LED will light.If phases are reversed, the red fault LED will be lit andcompressor operation is inhibited.If a fault condition occurs, reverse two of the supplyleads to the unit. Do not reverse any of the unit factorywires as damage may occur.Condenser Fan OperationNOTE: Certain models may be equipped with a lowambient control (LAC), and if so, the condenser fanmotor will have a delayed start until system refrigerantoperating pressure builds up. After starting, the fanmotor may or may not cycle depending upon ambientconditions. This is normal operation.Sequence of OperationCoolingCircuit R-Y1 makes at thermostat pulling in compressorcontactor, starting the compressor and outdoor motor.(See NOTE under CONDENSER FAN OPERATIONconcerning models equipped with low ambient control.)The G (indoor motor) circuit is automatically completedon any call for cooling operation or can be energized bymanual fan switch on subbase for constant air circulation.HeatingA 24V solenoid coil on reversing valve controls heatingcycle operation. Two thermostat options, one allowing“Auto” changeover from cycle to cycle and the otherconstantly energizing solenoid coil during heatingseason—thus eliminating pressure equalization noiseexcept during defrost, are to be used.On “Auto” option a circuit is completed from R-B/W1 andR-Y1 on each heating “on” cycle, energizing reversingvalve solenoid and pulling in compressor contactorstarting compressor and outdoor motor. R-G also makestarting indoor blower motor. Heat pump heating cyclenow in operation.The second option has no “Auto” changeover position, butinstead energizes the reversing valve solenoid constantlywhenever the system switch on subbase is placed in“Heat” position, the “B” terminal being constantlyenergized from R. A thermostat demand for heatcompletes R-Y1 circuit, pulling in compressor contactorstarting compressor and outdoor motor. R-G also makestarting indoor blower motor.On a call for 2nd stage heating, circuit R-W2 makesat the thermostat pulling in the heat contactor for thestrip heat and blower operation. On a call for thirdstage heat, R-B/W1 breaks, dropping out heat pump,and R-W3 makes, bringing on second heat contactor, ifso equipped.Balanced ClimateTM ModeBalanced Climate™ is a great comfort feature that caneasily be applied under any normal circumstances.If the Bard air conditioning system is being set upin a typical environment where 72°F is the lowestcooling setpoint, remove the Y1/Y2 jumper and installa 2-stage cooling thermostat. This will increase thehumidity removal up to 35% and provide a much morecomfortable environment.This mode will also increase the supply temperaturewhen in heating mode. When Balanced Climate mode