valutazioni - 5, GPA: 4.6
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Facilità d'uso
The same equation can be used to determine the occupied or maximum ventilation rate to the building. For example, an output of 3.6 volts to the actuator provides a base ventilation rate of 5% and an output of 6.7 volts provides the maximum ventilation rate of 20% (or base plus 15 cfm per person). Use Fig. 38 to determine the maximum setting of the CO2 sensor. For example, a 1100 ppm set point relates to a 15 cfm per person design. Use the 1100 ppm curve on Fig. 38 to find the point when the CO2 sensor output will be 6.7 volts. Line up the point on the graph with the left side of the chart to determine that the range configuration for the CO2 sensor should be 1800 ppm. The EconoMi$er IV controller will output the 6.7 volts from the CO2 sensor to the actuator when the CO2 concentration in the space is at 1100 ppm. The DCV set point may be left at 2 volts since the CO2 sensor voltage will be ignored by the EconoMi$er IV controller until it rises above the 3.6 volt setting of the minimum position potentiometer. Once the fully occupied damper position has been determined, set the maximum damper demand control ventilation potentiometer to this position. Do not set to the maximum position as this can result in over-ventilation to the space and potential high-humidity levels. CO2 Sensor Configuration The CO2 sensor has preset standard voltage settings that can be selected anytime after the sensor is powered up. (See Table 7.) TR1 24 Vac COM TR 24 Vac HOT 1 2 3 4 5 EF EF1 + _ P1 T1 P T N EXH 2V 10V EXH Set Set 2V 10V 2V 10V DCV DCV Free Cool B C A D SO+ SR+ SR SO AQ1 AQ DCV Min Pos Open Max N1 C06038 Fig. 37 ---EconoMi$er IV Control CO2 SENSOR MAX RANGE SETTING 0 1000 2000 3000 4000 5000 6000 800 ppm 900 ppm 1000 ppm 1100 ppm RANGE CONFIGURATION (ppm) 2345678 DAMPER VOLTAGE FOR MAX VENTILATION RATE C06039 Fig. 38 ---CO2 Sensor Maximum Range Setting Use setting 1 or 2 for Bryant equipment. (See Table 7.) 1. Press Clear and Mode buttons. Hold at least 5 seconds until the sensor enters the Edit mode. 2. Press Mode twice. The STDSET Menu will appear. 3. Use the Up/Down button to select the preset number. (See Table 7.) 4. Press Enter to lock in the selection. 5. Press Mode to exit and resume normal operation. The custom settings of the CO2 sensor can be changed anytime after the sensor is energized. Follow the steps below to change the non-standard settings: 1. Press Clear and Mode buttons. Hold at least 5 seconds until the sensor enters the Edit mode. 2. Press Mode twice. The STDSET Menu will appear. 3. Use the Up/Down button to toggle to the NONSTD menu and press Enter. 4. Use the Up/Down button to toggle through each of the nine variables, starting with Altitude, until the desired setting is reached. 5. Press Mode to move through the variables. 6. Press Enter to lock in the selection, then press Mode to continue to the next variable. 30 Dehumidification of Fresh Air with DCV Control Information from ASHRAE indicates that the largest humidity load on any zone is the fresh air introduced. For some applications, a device such as an energy recovery unit can be added to reduce the moisture content of the fresh air being brought into the building when the enthalpy is high. In most cases, the normal heating and cooling processes are more than adequate to remove the humidity loads for most commercial applications. If normal rooftop heating and cooling operation is not adequate for the outdoor humidity level, an energy recovery unit and/or a dehumidification option should be considered. Step 7 —Adjust Evaporator- --Fan Speed Adjust evaporator-fan speed to meet jobsite conditions. Tables 8 and 9 show fan rpm at motor pulley settings for the 551C 024- --060 and 551B 036- --072 units. Tables 10 and 13 show maximum amp draw of belt-drive motor. Table 12 shows sound data. Refer to Tables 14-33 for performance data. See Table 34 for accessory static pressure drop. See Fig. 39 for the Perfect Humidity™ system static pressure drops. For units with electric heating, required minimum cfm is 900 for 551B/C 036; 1200 for 551B/C 048; 1500 for 551B/C 060 and 1800 for 551B 072 and 600 for 551C 024. Belt Drive Motors Fan motor pulleys are factory set for speed shown in Table 1. Check pulley alignment and belt tension prior to start-up. To change fan speed: 1. Shut off the unit power supply and tag disconnect. 2. Loosen the belt by loosening the fan motor mounting nuts. (See Fig. 40.) 3. Loosen movable pulley flange setscrew (See Fig. 41). 4. Screw movable flange toward fixed flange to increase speed and away from fixed flange to decrease speed. Increasing fan speed increases load on motor. Do not exceed maximum speed specified in Table 1. 5. Set movable flange at nearest keyway of pulley hub and tighten setscrew. (See Table 1 for speed change for each full turn of pulley flange.) 6. Adjust belt tension and align fan and motor pulleys per guidance below. NOTE: Once the required flange position is determined for the correct blower rpm, it is r...
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