Daikin RDT Installation And Maintenance Manual

Also see for RPS: Installation and maintenance manual Installation and maintenance manual Installation manual Manual

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Daikin RDT Installation And Maintenance Manual Manual pdf 50 page image

IM 893-10 • ROOFPAK SINGLEZONE UNITS 50 www.DaikinApplied.comsequenCes of oPeraTIonEconomizer OperationRefer to Figure 66. When the outdoor air is suitable for freecooling, the switch in enthalpy sensor OAE is in position “3”(line 248, Figure 66) energizing analog input AIX5. WhenAIX5 energizes, the economizer is enabled. (Note: If selectedfrom the keypad, the enthalpy decision can be made basedon outdoor temperature. In that condition, if the outdoorair temperature is less than or equal to the changeover setpoint, the economizer is enabled.) If cooling is required, theeconomizer dampers (ACT3) are modulated to maintain thedischarge air temperature setpoint. Analog input AIX5 drivesthe outdoor air dampers toward the open and closed (line256) position. If the outdoor air dampers are wide open andmore cooling is required, the dampers hold their positions andmechanical cooling is activated.When the outdoor air is not suitable for free cooling, the switchin enthalpy sensor OAE is in position “1,” de-energizing analoginput AIX5. (Alternatively, the outdoor air temperature is abovethe changeover setpoint plus the economizer changeoverdifferential). When the economizer is disabled, the dampersare held at their minimum position.Fixed Speed Compressor Operation4-Compressor/4-Stage UnitRefer to Figure 67 on page 65 and Figure 68: RPS061 Condensing Unit Control (With Fixed Speed ScrollCompressors) on page 67 as you read this sequenceof operation. In this configuration there are four equallysized compressors and two cooling circuits. In the followingdescription, compressor #1 is lead. However, if Auto Lead/LagStaging is selected on the keypad, the lead compressor is theone in the lead circuit with the least number of run hours.NOTE: Lead lag is not available with the variable speedinverter compressor.When the unit disconnect is closed, 115 V (ac) power issupplied directly from control transformer T1 to the compressorcrankcase heaters, HTR-1, 2, 3, and 4 (lines 836 - 848, 853)and motor protectors MP1, 2, 3, and 4 (lines 836 - 848, 854).This same 115 V (ac) source also goes through:• System switch, S1 (line 203, Figure 68 on page 64)• The optional phase voltage monitors, PVM1 and 2 (lines203, 802, not shown)• The optional ground fault relays, GFR1 and 2 (lines 203,802, not shown)Compressors are staged by 115 V (ac) power supplied to thefollowing:• Frost protect FP1 to CCB1-BI8 (line 812, not shown)—Optional when no hot gas bypass is ordered on the unit• Frost protect FP2 to CCB2-BI8 (line 823, not shown)—Optional when no hot gas bypass is ordered on the unit• HP relay R1 to CCB1-BI7 (lines 812)• HP relay R2 to CCB2-BI7 (lines 823)• Compressor contactor status M1 to CCB1-BI9 (line 812)• Compressor contactor status M2 to CCB2-BI9 (line 823)• Compressor contactor status M3 to CCB1-BI10 (line 814)Cross Circuit LoadingSee line 812, Figure 68. During a call for cooling, if HP1 issatisfied, then DO1 closes. If MMP1 and MP1 are satisfied,then M1 compressor contactor is energized to bring oncompressor 1 on refrigerant circuit 1 (line 708 - 710, Figure 63.The M1 auxiliary brings on:• Required condenser fans (line 854)• Liquid line drop solenoids (lines 855 and 856)The drop solenoids are electrically energized by compressorcontactor auxiliary contacts. They open when the firstcompressor turns ON and they close when the last compressorturns OFF.Compressor 2 (refrigerant circuit 2) is the 2nd stage of coolingand is brought on in the same manner (line 823, Figure 68 andlines 708 - 710, Figure 63).Circuit 2 condenser fans and solenoids are controlled in thesame manner on lines 861 - 865).The 3rd stage of cooling is controlled by DO2 (line 814) andbrings on compressor 3 if MMP3 and MP3 are satisfied.The 4th stage of cooling is controlled by DO4 (lines 826) andbrings on compressor 3 if MMP3 and MP3 are satisfied.Lead Circuit LoadingThe loading and unloading process is similar except that bothcompressors in the lead cooling circuit 1 energize beforeenergizing any compressors in lag circuit 2.HeatingGas Furnace, Super Modulating Burner (20:1Turndown)Refer to Figure 66 on page 63 for a sequence of operation.