Isolated Areas:
Effective dehumidification may require that ducting
be branched to isolated, stagnant air flow areas. Use 8" or larger
diameter branch ducting to each of two or three areas, use 6" or
larger to each of four or more areas. Provisions must be made to
provide airflow from supply locations to central return location.
Proper air distribution is important to ensure even humidity control
and heat distribution throughout the structure. See Figure 1.
Connecting to existing HVAC systems:
An optional 10" check
backdraft damper is available from the factory to prevent reverse
air flow through the UA-90H. If the UA-90H is ducted to the supply
of an air handler, the check damper should be placed in the UA-
90H supply duct. Ventilation operation is controlled by the remote
controls offered with the UA-90H. These controls determine the
time/frequency that the unit introduces outside air. The amount of
outside air can be restricted by the blade damper in the 6" collar.
Some control options require a 6" motorized damper be installed in
the 6" fresh air duct.
IMPORTANT
Contact the factory when connecting to a static pressure of
greater than or equal to +.5" WG.
4.4B Ducting for Fresh Air — Option
Fresh air may be brought into the structure by connecting an
insulated duct from outside the structure to the 6" inlet of the UA-
90H. Advantages of this form of ventilation include:
1. Outside air is filtered before entering the building.
2. Outside air will be dehumidified before entering if the UA-90H
is running in dehumidification mode.
3. Drawing air from outside and blowing inside aids in slightly
pressurizing the structure. This helps prevent dirty and humid
air from entering elsewhere. It also reduces the potential for
carcinogenic radon gas to enter and provides a small amount
of make-up air for open combustion and exhaust devices like
the clothes drier, fireplace, and water heater.
4. Exhaust fans are recommended in the bath rooms and
kitchen.
In cold climates or areas where the outdoor dew point is low at
times, ventilation can be used to dehumidify the structure, making
the UA-90H capable of year-round drying. This is accomplished
by bringing the dry, low dew point air into the structure during
these times. This approach is often more economical than running
the dehumidifier to remove excess moisture from the structure.
In cold climates, it is critical to adequately ventilate to reduce the
inside moisture content to avoid moisture accumulating in the wall
cavities. For example; in a house that experiences condensation on
the interior surface of the windows during the winter, increasing the
amount of ventilation will often cure the problem.
An insulated 6" diameter duct is generally sufficient to provide up
to 75 CFM of outside air. Large quantities of outside air will impact
UA-90H performance positively or negatively, depending upon the
inside and outside air conditions.
The outside air duct should be connected to the 6" round collar on
the front of the unit. The amount of outside air can be restricted
by the blade damper in the 6" collar. These controls determine
the time/frequency that the unit introduces outside air. The
amount/frequency of ventilation should be based on the size and
occupancy of the residence. If you are unsure of your ventilation air
requirements or have need for higher air flows, consult the factory
by calling 1-800-533-7533 for assistance.
4.4C Installation in a Basement or Crawlspace with an
Existing Forced Air HVAC System.
Basement Installation:
Install a separate 10" return for the UA-
90H in a central area of the structure. Optional: Duct the supply
of the Ultra-Aire to a 10" x 10" x 10" tee/damper, adjusted to
20% open to the basement. Duct the other side of the tee to the
air supply of the existing HVAC system with a backdraft damper.
Connect a duct from outside to the 6" collar of the Ultra-Aire if you
wish to provide ventilation air. See Figure 2.
FOR HVAC INSTALLER ONLY
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Ultra-Aire 90H Installer’s & Owner’s Manual
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Ultra-Aire 90H Installer’s & Owner’s Manual
