The Aprilaire 4655 manual digital control humidistat is designed to be used with low voltage service to offer control of your humidification equipment, and is made to be used with the Aprilaire humidifier 4655 500. The Aprilaire manual humidistat is designed to be installed on the cold air return duct or on an interior wall in the living area of the home.

To determine the relative humidity in the home, slowly turn the knob on the control clockwise and counterclockwise and listen for 2 clicks. The actual relative humidity in the home is between the 2 clicks. It is important to anticipate a drop in outdoor temperature and reduce the humidity setting in order to avoid excess condensation. The excess condensation occurs because the indoor relative humidity is higher than what the home can support for the current outdoor temperature. To adjust the humidity setting, simply rotate the control knob to the desired setting. Provided the HVAC system fan is operating and the humidification level is lower than the new set point, the manual humidistat will activate the humidifier.

• The indoor humidity should be set to match the outdoor temperature to prevent water from running down the sides of your windows
• When the relative humidity reverses the Aprilaire 4655 manual digital control humidistat will close the control switch. The Aprilaire 4655 manual digital control humidistat can either be wall mounted or mounted on the return Plenum
• This even water distribution ensures maximum evaporation from your humidifier

Shipping Note: Shipping to Alaska or Hawaii is not available for this item.

Warranty: 90 Day Woot Limited Warranty