Aprilaire 1750A-1770A How Does the Dehumidifier Work?, How Does the Optional Ventilation Work?

Optional – two zone dehumidification

The dehumidifier can be installed to dehumidify just one area or zone (i.e. the whole home) or, as shown in the illustration to the right, can be installed to dehumidify two separate areas or zones (i.e. the home and the basement) independently. Each zone can have its own humidity level setting/control when installed with the Model 76 Control or Model 8910 Home Comfort Control™, or the two zones can share the same setting/control. You and your installing contractor determine which zone is the most important to control and this becomes the “Primary” zone while the other is the “Secondary” zone. The dehumidifier will turn

on and open/close dampers to direct the dry air and satisfy the needs of the Primary zone. If there is no demand from the Primary zone, the Secondary zone will be dehumidified. Contact your installing contractor for details about Primary/Secondary Zoned Dehumidification.

DAMPERS

TO

SECONDARY

ZONE

TO/FROM

PRIMARY ZONE

DAMPERS

FROM

SECONDARY

ZONE

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How Does the Dehumidifier Work?

When the dehumidifier turns on, the blower circulates the air for three (3) minutes before measuring the humidity level of the air. The green status light below the control setting flashes when the dehumidifier is circulating the air. If the humidity of the air is higher than the setting, the compressor turns on and the green Status light is lit continuously. The dehumidifier turns off after the humidity level of the air has dropped below the setting.

Optional – Heating and Cooling System Blower Operation

Your installing contractor may have configured the dehumidifier to turn on the heating and cooling system blower when the dehumidifier turns on to allow for improved circulation of the dry air.

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How Does the Optional Ventilation Work?

With the ventilation option installed (if you are unsure if this option has been installed, contact your installing contractor), the dehumidifier will bring in outside air for the amount of time set on the Cycle Time adjustment during the set Cycle Period.

Your dehumidifier will work with your heating and cooling system blower to satisfy the ventilation requirements that have been set. For example, if the Cycle Time is set for 20 minutes and the Cycle Period for 1 hour, you will get outdoor air introduced to your home for 20 minutes every hour. When your heating and cooling system blower operates the dehumidifier blower will turn on and will open a normally-closed damper in the duct that brings in outdoor air. If it is getting close to the end of the Cycle Period and your heating and cooling system blower has not operated, the dehumidifier will turn on the system blower. Using the 20 minute per hour settings as an example, if the heating or cooling comes on for only 10 minutes, the dehumidifier control will turn on the system blower for the final 10 minutes of the 1-hour cycle period to deliver the required amount of fresh air.

Outdoor air that is brought in will mix with the air circulating through your heating and cooling system. The dehumidifier will monitor the air in your home and if the humidity level gets higher than the setting, it will turn on the compressor to remove the moisture.

An outdoor sensor, if installed with the ventilation option, will monitor the temperature of the outdoor air and if the temperature exceeds 100°F (38°C) or drops below 0°F (-18°C) ventilation will not occur. If the outdoor temperature is between 20°F (-7°C) and 0°F (-18°C), ventilation will only occur when your heating system operates.

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