Bard WA381 Installation Instructions Manual

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Bard WA381 Installation Instructions Manual Manual pdf 17 page image

Manual 2100-398Page 15SEQUENCE OF OPERATIONCOOLING – Circuit R-Y makes at thermostat pullingin compressor contactor, starting the compressor andoutdoor motor. The G (indoor motor) circuit isautomatically completed on any call for coolingoperation or can be energized by manual fan switch onsubbase of constant air circulation. On all 230 voltunits there is a one minute off delay on the blowermotor. 460 volt models do not have an off delay. On acall for heating, circuit R-W1 make at the thermostatpulling in heat contact for the strip heat and bloweroperation. On a call for second stage heat, R-W2 makesbringing on second heat contactor, if so equipped.COMPRESSOR CONTROL MODULEThe compressor control module is standard on theWA391, WA484, WA491and WA602 models coveredby this manual and is optional on the WA423 model.The compressor control is an anti-short cycle/lockouttimer with high and low pressure switch monitoring andalarm relay output.Adjustable Delay On Make And Break TimerOn initial power up or any time power is interrupted tothe unit 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 pressureswitch (and low pressure switch if employed) is closed,the compressor contactor is energized. Upon shutdownthe delay or break timer starts and prevents restart untilthe delay on break and delay on make periods haveexpired.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 relaycircuit will energize. Recycling the wall thermostatresets the manual lockout.Low Pressure Switch, Bypass, and LockoutSequenceIf 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 manuallockout.Alarm Relay OutputAlarm terminal is output connection for applicationswhere alarm relay is employed. This terminal ispowered whenever compressor is locked out due toHPC or LPC sequences as described.NOTE: Both high and low pressure switch controls areinherently automatic reset devices. The highpressure switch and low pressure switch cut outand cut in settings are fixed by specific airconditioner or heat pump unit model. Thelockout features, both soft and manual, are afunction of the Compressor Control Module.ADJUSTMENTSAdjustable Delay on Make and Delay on BreakTimerThe potentiometer is used to select Delay on Break timefrom 30 seconds to 5 minutes. Delay on Make (DOM)timing on power-up and after power interruptions isequal to 2 minutes plus 10% of Delay on Break (DOB)setting:0.5 minute (30 seconds) DOB = 123 second DOM1.0 minute (60 seconds) DOB = 126 second DOM2.0 minute (120 seconds) DOB = 132 second DOM3.0 minute (180 seconds) DOB = 138 second DOM4.0 minute (240 seconds) DOB = 144 second DOM5.0 minute (300 seconds) DOB = 150 second DOMDuring routine operation of the unit with no powerinterruptions the compressor will operate on demandwith no delay.Typical Settings for Dual Unit Installation:Unit 1: DOB set at 2 minutes, and DOM is 132 secondsUnit 2: DOB set at 4 minutes, and DOM is 144 secondsPRESSURE SERVICE PORTSHigh and low pressure service ports are installed on allunits so that the system operating pressures can beobserved. A pressure table can be found later in themanual covering all models. It is imperative to matchthe correct pressure table to the unit by model number.