9
Preparation and Setup
The fan factory default direction is through top
A
of the
hood. However,
the fan can be rotated
to vent through the
rear
B
of the hood.
When planning new ductwork, always find the shortest,
most direct route to the outside.
Duct Length Calculation Table
The maximum straight duct length for the hood is deter-
mined by the type of duct used. See the chart below.
Duct Size
Maximum Duct Run
8-inch Round
60 feet
10-inch Round
50 feet
3 1/4-in x 10-in Rectangular
50 feet
For each elbow and transition added, a certain length must
be subtracted from the maximum duct run to compensate
for wind resistance.
To determine your maximum length:
1. Start with the total max. length of your duct run, then
2. Subtract all of the ductwork equivalent lengths (see
chart below).
Ductwork Equivalent Lengths
Piece
Subtract
Piece
Subtract
8-inch
90° Elbow
7 feet
10-inch 90° Elbow
5 feet
8-inch
45° Elbow
3 feet
10-inch 45° Elbow
2 feet
3-in x 10-inch
to Round 90°
Transition
25 feet
3¼ in x 10 in to 8
in / 10 in Round
Transition
4 feet
Roof Cap
*
Wall Cap with
Damper
*
* The equivalent lengths of roof and wall caps vary with
model and configuration.
A
B
Planning the Ductwork
WARNING
• To prevent combustion by-products, smoke or odors
from entering the home and to improve efficiency, tape
all duct joints securely.
• Range hoods may interrupt the proper flow of smoke
and combustion gases from furnaces, gas water heat-
ers, and fireplaces. To avoid drawing lethal gases into
the home, follow the manufacturer’s recommendation
for these devices and consult NFPA and ASHRAE rec-
ommendations.
• Failure to install a remote blower or proper ductwork
may result in a backdraft and/or insufficient venting of
smoke and fumes.
•
DO NOT
install an additional in-line or external blower
to increase the length of the duct run. Even small dif-
ferences between blower air flow rates can greatly
reduce the air draw by the hood.
CAUTION
To reduce the risk of fire and to properly exhaust air, be
sure to duct air outside the house or building. Do not vent
exhaust air into spaces within walls or ceilings or into
attics, crawl spaces or garages.
• Local building codes may require the use of makeup air
systems with ventilation systems that move air greater
than the specified movement rate (CFM).
The specified rate varies based on locale. Consult a
qualified HVAC specialist when designing the system
for the requirements in your area and to assure optimal
performance.
• All ductwork materials (including screws and foil tape)
must be purchased separately.
• Make sure ductwork does not interfere with floor joists
or wall studs.
• Fasten all joints with sheet metal screws and seal with
certified duct tape or foil tape.
• Two 8-inch exhausts may be merged into one 10-inch
duct using Dacor transition kit AHT10. See page 18
for details.
Vent Direction Options
WARNING
During duct installation, make sure there are no
obstructions that keep the damper flaps on the top of the
hood from opening.
Summary of Contents for Distinctive DTHP30
Page 30: ...28 Notes ...
Page 31: ......
