Page. 9
Ductwork Preparation
Discharge Direction
The exhaust air is discharged upwards through a duct or
directly through the outside wall into the open.
Ducting Recommendations
Proper performance is dependent upon proper ducting.
Local building codes may require the use of make-up air
systems when using ducted ventilation systems greater
than specified cubic feet per minute (CFM) of air
movement. The specified CFM varies from locale to
locale. It is the responsibility of the owner and the installer
to determine if additional requirements and/or standards
apply to specific installations.
DO NOT USE FLEXIBLE DUCT;
it creates back pressure/
air turbulence and reduces performance. Always install a
metal vent cover where the ductwork exits the house.
Hood must be vented to the outside of building only.
COLD WEATHER
installations should have an additional
backdraft damper installed to minimize backward cold air
flow and a nonmetallic thermal break to minimize
conduction of outside temperatures as part of the
ductwork. The damper should be on the cold air side of
the thermal break. The break should be as close as
possible to where the ducting enters the heated portion
of the house.
MAKE-UP AIR:
Local building codes may require the use
of make-up air systems when using ducted ventilation
systems greater than specified CFM of air movement. The
specified CFM varies from locale to locale. It is the
responsibility of the owner and the installer to determine if
additional requirements and/or standards apply to specific
installations.
To reduce risk of fire and to properly exhaust air, be sure
to duct air outside. Do not vent exhaust air in spaces with
walls or ceilings or into attics, crawl spaces or garages.
The unit cannot be used in conjunction with a recirculation
unit.
Thermador recommends not exceeding 50 ft
(15.24 m) equivalent of duct.
Keep duct runs as short and straight as possible. Elbows
and transitions fittings reduce air flow efficiency. Back to
back elbows and “S” turns give very poor delivery and are
not recommended.
A short, straight length of duct at the inlet of a remote
blower gives the best delivery.
Hoods are supplied with a 10" (254 mm) transition. A
locally supplied transition is required for other sizes.
Use the
“Equivalent Duct Lengths for Commonly Used
Transitions”
table to compute permissible lengths for duct
runs to outdoors.
