Aprilaire 1750A, 1770A Vent-Timed,HVAC Initiates Ventilation, Dehumidification During Ventilation

VENTILATION oR Air Cycling (continued)

SEQUENCE OF OPERATION

Vent-Timed, HVAC Initiates Ventilation

•Ventilation will occur whenever there is an HVAC fan (Gs) or heat (W) call and will continue until the ventilation time has met the set Cycle

Time during the set Cycle Period.. During ventilation the dehumidifier damper output turns on, the ventilation damper opens, the dehumidifier blower turns on, and the Status LED flashes..

•When the HVAC heat or fan call has ended or when the ventilation time requirement has been met, the dehumidifier damper output turns off, the ventilation damper closes, and the dehumidifier blower turns off along with the green Status LED..

•Two minutes must elapse following the end of a HVAC fan or heat call before the dehumidifier can initiate a ventilation cycle.

Vent-Timed, Dehumidifier Initiates Ventilation

•When the amount of time remaining in the Cycle Period is equal to the amount of Cycle Time required, the HVAC fan turns on, the dehumidifier damper output turns on, the ventilation damper opens, the dehumidifier blower turns on, and the Status LED flashes..

•When the ventilation time requirement has been met, the HVAC fan turns off, the dehumidifier damper output turns off, the ventilation damper closes, and the dehumidifier blower turns off along with the green Status LED..

•To prevent short cycling the fan, a ventilation cycle will not start unless there are at least 2 minutes remaining in the Cycle Period.

Dehumidification During Ventilation

When not controlled by the Model 70 Living Space Control or third-party control, the dehumidifier will continually measure the conditions of the incoming air during ventilation..

•The dew point of the air is measured 3 minutes after the dehumidifier blower is turned on and every 15 seconds while the blower is running.

•If the dew point of the air is above the setting on the control knob, the compressor turns on and the green Status LED switches to solid illumination..

•When the dew point of the air falls below the control knob set point, the compressor turns off and the Status LED flashes.

Vent-Auto

Ventilation in the Vent-Auto configuration is functionally the same as Vent-Timed operation, with the exception of the temperature limits applied to the incoming air..

•If the incoming air temperature is greater than or equal to 100°F, the ventilation damper closes. If the temperature drops to 95°F or lower during the same ventilation cycle, the ventilation damper will open..

•If the incoming air temperature is less than or equal to 0°F, the ventilation damper closes. If the temperature increases to 5°F or higher during the same ventilation cycle and the ventilation cycle was initiated by a HVAC heat (W) call, the ventilation damper will open..

•If the air temperature is less than or equal to 20°F and above 0°F, the ventilation damper will close unless a HVAC heat (W) call is initiated during the ventilation cycle.. If the air temperature drops to 0°F or below during the same ventilation cycle, the ventilation damper closes.. If the temperature rises to 25°F or higher during the same ventilation cycle, the ventilation damper will open..

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