Carrier 50TCQD14 Installation Instructions Manual

Also see for 50TCQD: Installation instructions

Contents

40TEMPERATUREENTHALPYRA TEMPABSOLUTE HUMIDITYECONOMIXINGAVAILABLENOT AVAILABLEES5 ES4 ES3 ES2 ES1 HLDUAL ENTHALPYHIGH LIMITSINGLE ENTHALPYP2 (T,RH)P1(T,RH)R AHUM(%RH)C12015Fig. 47 -- Single Enthalpy Curve and BoundariesTable 21 – Single Enthalpy and Dual Enthalpy High Limit Curves (EN Units)EnthalpyCurveTemp.Dry---Bulb (_F)Temp.Dewpoint (_F)Enthalpy(btu/lb/da)Point P1 Point P2Temp. (_F) Humidity %RH Temp. (_F) Humidity %RHES1 80.0 60.0 28.0 80.0 36.8 66.3 80.1ES2 75.0 57.0 26.0 75.0 39.6 63.3 80.0ES3 70.0 54.0 24.0 70.0 42.3 59.7 81.4ES4 65.0 51.0 22.0 65.0 44.8 55.7 84.2ES5 60.0 48.0 20.0 60.0 46.9 51.3 88.5HL 86.0 66.0 32.4 86.0 38.9 72.4 80.3Enthalpy SettingsWhen the OA temperature, enthalpy and dew point arebelow the respective setpoints, the outdoor air can be usedfor economizing. Fig. 47 shows the new single enthalpyboundaries in the W7220. There are 5 boundaries(setpoints ES1 through ES5), which are defined by drybulb temperature, enthalpy and dew point.Refer to Table 21 for ENTH CURVE setpoint values.The W7220 calculates the enthalpy and dew point usingthe OA temperature and humidity input from the OAenthalpy sensor. When the OA temperature, OA humidityand OA dew point are all below the selected boundary, theeconomizer sets the economizing mode to YES,economizing is available.When all of the OA conditions are above the selectedboundary, the conditions are not good to economize andthe mode is set to NO.Fig. 47 shows the 5 current boundaries. There is also ahigh limit boundary for differential enthalpy. The highlimit boundary is ES1 when there are no stages ofmechanical cooling energized and HL (high limit) when acompressor stage is energized.Table 21 provides the values for each boundary limit.Two--Speed Fan OperationThe W7220 controller has the capability to work with asystem using a 2--speed supply fan. The W7220 does notcontrol the supply directly but uses the following inputstatus to determine the speed of the supply fan andcontrols the OA damper to the required position.State Fan SpeedOCC LowY1 LowY2 HighW HighThe W (heating mode) is not controlled by the W7220 butit requires the status to know where to position the OAdamper for minimum position for the fan speed.The 2 speed fan delay is available when the system isprogrammed for 2 speed fan (in the System Setup menuitem). The 2 speed fan delay is defaulted to 5 minutes andcan be changed in the Advanced Setup menu item. Whenthe unit has a call for Y1 In and in the free cooling modeand there is a call for Y2 In, the 2--speed fan delay startsand the OA damper will modulate 100% open, the supplyfan should be set to high speed by the unit controller.After the delay one of two actions will happen: