Duct Sizing:
For total duct lengths up to 25', use a
minimum 8" diameter round or equivalent rectangular. For longer
lengths, use a minimum 10" diameter or equivalent. Grills or
diffusers on the duct ends must not excessively restrict air flow.
Isolated Areas:
Effective dehumidification may require that ducting
be branched to isolated, stagnant areas. Use 6" or larger diameter
branch ducting to each of two or three areas; use 4" or larger to
each of four or more areas.
3.4C Ducting for Fresh Air
Fresh air can be brought into the structure by connecting a duct
from outside to the 6" Ultra-Aire inlet and by turning on the fan
switch or activating the humidity control on units with the humidity
control panel. Activate the ventilation timer on units with the
ventilating & humidity control panel to bring in fresh air. 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 Ultra-
Aire is running.
3. Drawing air from outside and blowing inside aids in slightly
pressurizing the structure. This helps prevent unfiltered and
undehumidified air from entering elsewhere. It also reduces
the potential for carcinogenic radon gas to enter and provides
makeup air for open combustion and exhaust devices like the
clothes drier, fireplace, and water heater.
4. The need for an alternate ventilation device may be eliminated.
An insulated 6" diameter duct is generally sufficient to provide up
to 125 CFM of outside air. Large quantities of outside air will impact
Ultra-Aire performance positively or negatively, depending upon the
difference between inside and outside air conditions. Consult the
factory by calling 1-800-533-7533 for recommendations regarding
the use of higher flows with your specific application.
The outside air duct should be connected to the 6" round collar
on top of the unit. The 6" round collar includes a manual damper.
Adjust the manual damper to provide the desired amount of fresh air
for ventilation. The amount of fresh air should be based on the size
and occupancy of the residence. If you are unsure of your ventilation
air requirements, consult the factory by calling 1-800-533-7533 for
assistance.
3.4D Installation in a Basement or Crawlspace with an
Existing Forced Air HVAC System.
If the structure in which the Ultra-Aire is to be installed has an
existing forced air HVAC system, utilize the HVAC system to make
the Ultra-Aire installation easier.
If the existing system has multiple returns, select one to disconnect
from the existing forced air system and use it for the dedicated
Ultra-Aire return. Always select a return from a central location
in the structure in an area that is always open to the rest of the
structure. Do not use a return from a room that may have its door
closed much of the time.
Basement Installation:
Locate a separate return for the Ultra-Aire
in a central area of the structure. Duct the supply of the Ultra-Aire
to a 8" x 8" x 8" tee/damper that is 30% open to the basement.
Duct the other side of the tee to the air return of the existing HVAC
system. If the existing HVAC system has a central return, duct the
other side of the tee to the air supply of the existing HVAC system.
Connect a duct from outside to the 6" collar of the Ultra-Aire if you
wish to provide fresh make-up air.
Crawlspace Installation:
Locate a separate return for the Ultra-
Aire in a central area of the structure. Duct the supply of the
Ultra-Aire to a 8" x 8" x 8" tee/damper that is 30% open to the
FOR HVAC INSTALLER ONLY
4
Ultra-Aire 100V Installer’s & Owner’s Manual
