Ductwork Preparation; Ducting Recommendations - Thermador PROFESSIONAL SERIE Operating And Installation Manual

Ductwork Preparation

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 speci ed cubic feet per minute (CFM) of air
movement. The speci ed 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 use metal
ductwork.
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.
English 6
For safety reasons, ducting should vent directly outdoors
(not into an attic, underneath the house, into the garage or
into any enclosed space).
The unit cannot be used in conjunction with a recirculation
unit.
®
THERMADOR recommends not exceeding 50 equivalent
length (ft) (15.24 m) 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) round transition. A
locally supplied transition is required for other sizes.
Use Table 1 on page 7 to compute permissible lengths for
duct runs to outdoors.