DECTRON
Dectron, Inc. March 2012
Owner’s Manual
DSH/DSV/RSH/DBH/RBH Series Dehumidifier
Door & Window Design Building Construction
Data subject to change without notice.
Glass set to outside of
frame. Glass just
under cross-members
will sweat.
SUPPLY DUCT
DIFFUSER
DIFFUSER
Warm, dry supply
air flows evenly
along entire
surface.
SEE THE INSTALLATION
SECTION FOR MORE
DETAILS.
Glass set to inside
of frame remains
dry.
Exterior Wall
Thermal breaks in
frames reduce
heat transfer &
sweating.
Multiple-glazing
reduces heat
transfer &
sweating.
SUPPLY DUCT
Each cross-member
acts as an air dam.
Supply air covers only
part of the surface.
Other surfaces will not
be covered with supply
air and will sweat.
NOT
RECOMMENDED
RECOMMENDED
Exterior Wall
Window Design
Special attention must be paid to the exterior glass components such as windows and patio doors. Due to their
low insulation values, windows are usually the building element with the lowest inside-surface temperature. In
cold climates, windows and exterior glass doors should
1. be double-paned or even triple-paned (to reduce heat transfer through the glass),
2. have frames with thermal breaks (to reduce heat transfer through the frames), and
3. be glazed to the inside of frames and walls (to allow smooth airflow along the inner surfaces).
Even a triple-pane window can have an inside-surface temperature below the room dew point. The entire sur-
face area of exterior windows MUST be blanketed with warm supply air from the perimeter air-distribution system
to raise the window’s inside surface temperature above the dew point and thus prevent condensation. Windows
must be designed to allow unobstructed air movement on the inside surface. Avoid windows with panes recessed
to the outside. Avoid heavy window frames which protrude to the inside. Both of these prevent proper air move-
ment and result in condensation.
See “Coanda effect” in ASHRAE Handbook of Fundament
als.
Other building elements which create thermal bridges must either be avoided or be blanketed with warm air to
prevent condensation damage. Skylights are especially vulnerable to condensation, since precipitation falling on
the skylight causes rapid cooling and a direct warm-air supply can be difficult to achieve.
BUILDING
CONSTRUCTION
21
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