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Hersteller: Greenheck Fan Dateigröße: 697.94 kb Dateiname: Unterrichtssprache:

(Refer to Electric Heater Application/Operation for electric preheater location). When electric preheat frost control is initiated, the electric preheater will turn on and warm the air entering the energy wheel to avoid frosting. The thermodisc temperature sensor installed has a 5°F nonadjustable set point. For custom temperature set point thermodiscs, please contact the factory. Use the following test procedure for troubleshooting. Testing: .. ........................................................................................ and the wheel pressure sensor. The heater should turn on. .. ........................................................................................................ on or temporarily jumper the airflow pressure switch in the preheater control center to avoid nuisance tripping of the pressure switch. Also check the airflow switch pressure tap located at the supply discharge blower to ensure the tubing is connected and the tap is not blocked. Remember to remove the jumpers. Modulating wheel frost control includes a variable frequency drive in addition to the thermostat and pressure sensor. When modulating wheel frost control is initiated, the variable frequency drive will reduce the speed of the wheel. Reducing the speed of the energy wheel reduces its effectiveness, which keeps the exhaust air condition from reaching saturation, thus, eliminating condensation and frosting. If the outdoor air temperature is greater than the frost threshold temperature OR the pressure differential is less than the set point, the wheel will run at full speed. If the outdoor air temperature is less than the frost threshold temperature AND the pressure differential is greater than the set point, the wheel will run at reduced speed until the pressure differential falls below the set point. The temperature and pressure differential set points are set at the factory, but are field-adjustable (refer to VFD section for more information). The variable frequency drive will be fully programmed at the factory. 14 Energy Recovery Ventilator Economizer Application/Operation The energy recovery wheel operation can be altered to take advantage of economizer operation (free cooling). Two modes are available: 1. De-energizing the wheel 2. Modulating the wheel A field supplied call for cool (Y1) is required. De-energizing the wheel is accomplished with a signal from a Temperature or Enthalpy sensor mounted in the air intake compartment. This primary sensor will de-energize the energy wheel when the outdoor air temperature (factory default is 65.F) or enthalpy (factory default is the ‘D’ setting) is below the field adjustable set point. An Override temperature sensor is also furnished in the outdoor air intake compartment to deactivate economizer mode. The Override (with field adjustable set point) is set at some temperature lower than the primary sensor (factory default is 50.F). Effectively, the two sensors create a deadband where the energy recovery wheel will not operate and free cooling from outside can be brought into the building unconditioned. Testing Temperature Sensor with Override .. .................................................. Override thermostats down as low as they go. The wheel should be rotating. .. ............................................................ Temperature as high as it goes, and keep the Sensor with Override sensor as low as it will go. Override The wheel should stop rotating. .. ............................................................................................ wheel should start rotating. .. ...................................................................................... for economizer operation to begin. Set the Override sensor at desired point for economizer operation to end (factory default is 65.F and 50.F, respectively). Enthalpy Sensor with Override .. .............................................................. C7400 Solid State Enthalpy Sensor from terminal So on the enthalpy controller. Also, disconnect the 620 ohm resistor from terminal Sr on the enthalpy controller. Enthalpy Turn unit power on. The Sensor with LED on the enthalpy Override controller should light and the energy recovery wheel should not rotate. .......................................................................... ohm resistor to terminal Sr on the Enthalpy enthalpy controller. Turn unit power on. Controller The LED on the enthalpy controller should not light and the energy recovery wheel should energize and rotate. If these steps provide the results described, the enthalpy economizer is working properly. .. ................................................................................................ Enthalpy Sensor to terminal So. Modulating the Wheel In applications in which an internal heat gain is present in the space, the rotational speed of the energy wheel may be modulated (via variable frequency drive) to avoid overheating the space during the winter. The speed of the en...

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