Aprilaire 1750A Installation Instructions Manual page 13

TWO ZONE – PRIMARy AND SECONDARy ZONED INSTAllATION
SEQUENCE Of OPERATION
• T he Primary Zone takes priority during dehumidifier operation. Primary Zone sampling occurs at the end of each Cycle Period and Secondary
Zone sampling occurs at the beginning of each Cycle Period . If the dehumidifier is actively dehumidifying the Primary Zone at the beginning of
the Cycle Period, Secondary Zone sampling will not occur during that Cycle Period . Primary Zone sampling will also override a Secondary Zone
dehumidification demand .
• I f a Model 76, Model 8910 Home Comfort Control
Primary Zone will occur on-demand . Secondary Zone sampling will occur at the beginning of each Cycle Period unless actively dehumidifying
the Primary Zone . A Primary Zone demand will override a Secondary Zone demand .
• A t the onset of Primary Zone sampling, the dehumidifier damper output turns on, the dehumidifier blower turns on, and the green Status LED
flashes . After three minutes, the dew point of the incoming air is measured and compared to the setting on the control knob . If the dew point
of the incoming air is above the setting, the compressor turns on and the green Status LED switches to solid illumination . If the dew point is
below the setting, the dehumidifier damper output turns off and the green Status LED begins flashing as the dehumidifier begins Secondary
Zone sampling . After three minutes of Secondary Zone sampling, the dew point of the incoming air is measured and compared to the setting
on the control knob . If the dew point of the incoming air is above the setting, the compressor turns on and the green Status LED switches
to solid illumination . If the dew point is below the setting, the dehumidifier blower turns off along with the green Status LED . (See page 19,
MODEL 76 EXTERNAL CONTROL for Primary Zone dehumidification sequence when a Model 76 is installed.)
• T he dew point of the incoming air is continuously monitored during compressor operation. When the dew point of the incoming air falls below
the setting on the control knob, the dehumidifier damper output turns off and the dehumidifier compressor and blower turn off along with the
green Status LED .
• A fter the dehumidifier blower has turned off, one minute must elapse before it can be turned on again (i.e., following a Primary Zone
sampling) . If one minute has not elapsed, the Status LED will flash and the dehumidifier blower will turn on after one minute .
, or other Third-Party Control is installed in the Primary Zone, dehumidification of the
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(CONTINUED)
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