Bard WA3S1 Installation Instructions Manual

Contents

Bard WA3S1 Installation Instructions Manual Manual pdf 16 page image

Manual 2100-451EPage 16 of 24COMPRESSOR CONTROL MODULEThe compressor control module is standard on the modelscovered by this manual. The compressor control is ananti-short cycle/lockout timer with high and low pressureswitch monitoring and alarm relay output.Adjustable Delay On Make And Break TimerOn initial power up or anytime power is interrupted to theunit, the delay on make period begins, which will be 2minutes plus 10% of the delay on break setting. Whenthe delay on make is complete and the high pressure andlow pressure switches are closed, the compressorcontactor is energized. Upon shutdown the delay orbreak timer starts and prevents restart until the delay onbreak and delay on make periods have expired.During routine operation of the unit with no powerinterruptions, the compressor will operate on demandwith no delay.High Pressure Switch and Lockout SequenceIf the high pressure switch opens, the compressorcontactor will de-energize immediately. The lockouttimer will go into a soft lockout and stay in soft lockoutuntil the high pressure switch closes and the delay onbreak time has expired. If the high pressure switchopens again in this same operating cycle, the unit will gointo manual lockout condition and the alarm relay circuitwill energize. Recycling the wall thermostat resets themanual lockout.Low Pressure Switch, Bypass and Lockout SequenceIf the low pressure switch opens for more than 120seconds, the compressor contactor will de-energize andgo into a soft lockout. Regardless the state of the lowpressure switch, the contactor will reenergize after thedelay on make time delay has expired. If the lowpressure switch remains open, or opens again for longerthan 120 seconds the unit will go into manual lockoutcondition and the alarm relay circuit will energize.Recycling the wall thermostat resets the manual lockout.Optional Low Ambient ControlAn optional low ambient control is available for bothfactory and field installed options. The low ambientcontrol is to be applied to the WA3S/WA4S/WA5Smodels when operation below 50°outdoor conditions areanticipated. Without this device, the evaporating pressurewould fall off, and the indoor coil would ice over.The fan cycling control cycles the fan motor on, once theliquid refrigerant pressure reaches 350 psig, and off, onceit has dropped to 225 psig. It will continue to cyclebetween these parameters depending on outdoortemperatures and the load/stage of the system.This cycling maintains a minimum liquid pressureaffecting the minimum suction pressure. This effectinsures an evaporating temperature that is slightly abovethe point of ice formation on the evaporator.SERVICE HINTS1. Maintain clean air filters at all times. Also, do not closeoff or block supply and return air registers. This reducesair flow through the system, which shortens equipmentservice life as well as increasing operating costs.2. Check all power fuses or circuit breakers to be sure theyare the correct rating.3. Periodic cleaning of the outdoor coil to permit full andunrestricted airflow circulation is essential.Frequency of coil cleaning will depend on duty cycle ofequipment, type of use and installation site variables.Telecommunication type installations in high trafficareas or in areas none too frequent to airborne debris,will require more frequent coil maintenance than thosein areas not subject to those conditions.SEQUENCE OF OPERATIONNON-ECONOMIZERStage 1 (Y1) cooling call activates Step 1 (partialcapacity, 66%) of compressor capacity.Stage 2 (Y2) cooling call activates Step 2 (full capacity,100%) of compressor capacity.WITH ECONOMIZERStage 1 (Y1) cooling call goes to economizer controls fordecision:- If Enthalpy Control decides outdoor conditionsare suitable for free cooling, the economizer willoperate.• If Stage 2 cooling call is issued duringeconomizer operation, the economizer willclose and the compressor will go straight toStep 2 full capacity operation.- If Enthalpy Control decides outdoor conditionsare not suitable for free cooling, the economizerwill not operate (or close) and Step 1 of thecompressor will operate.• If Stage 2 cooling call is issued, thecompressor will shift to Step 2 full coolingcapacity operation.BLOWER TIME DELAY DISABLEIn certain applications, there is a requirement/desire todisable the blower one-minute delay (where blower runsfor 1 minute after thermostat has satisfied). This could bein a situation that has requirements for fire dampers, orjust otherwise desirable.To disable the blower time delay on the WA*S models, itcan be done by simply disconnecting a single wire at theCompressor Control Module (CCM). Disconnect powerto the unit, remove both the inner and outer control panelcovers, locate the CCM (left side of control panel abovelow voltage box). Next, locate the “gray” wire attached tothe “R” terminal of the CCM. Remove the “gray” wireand tape the end off.Reverse the steps installing the inner and outer controlpanel covers, and turn the power back on.