Ventilation Guide

8 | Wolf Customer Care 800.222.7820
Step 1: Determine the Duct Run
IMPORTANT NOTE: Consult a qualified HVAC professional
for specific installation and ducting applications.
Check local codes: Consult a qualified HVAC professional
to ensure all applicable codes are followed. Refer to the
installation guide for your specific Wolf ventilation product.
Minimize the duct run: The length of the duct run and
number of elbows and transitions can have a significant
eect on ventilation performance. Keep the duct run as
short as possible and limit the number of elbows and tran-
sitions. Do not use flexible metal ducting.
Elbows and transitions: Do not place elbows and tran-
sitions back-to-back. Whenever possible, include a
minimum 15"
(381) straight ducting between elbows and
transitions to increase ventilation performance.
Use recommended duct sizes: Depending on the specific
ventilation product, Wolf recommends 6"
(152), 8" (203), or
10"
(254) ducting. Smaller duct sizes will significantly reduce
ventilation performance.
Cold weather installations: Cold weather installations may
require an additional backdraft damper to minimize back-
ward flow of cold air. All Wolf ventilation hoods, except
low-profile wall hoods, come with a backdraft damper
connected to the transition. Downdraft systems do not
have a backdraft damper.
High altitudes: Ventilation systems are less eective at
altitudes above 5,000'
(1524 m). At these altitudes, you
should estimate a 20–25% reduction in CFM performance.
A higher CFM blower and increasing the duct size is rec-
ommended.
Make-up air: Make-up air may be required to replace air
removed by the ventilation system. Consult a qualified
HVAC professional for specific applications.
Determine the Duct Run
Equivalent duct length: Determine the equivalent length of
the duct run using the equivalent duct lengths for com-
monly used ducting listed in the chart on the following
page. Follow these steps and use the chart to calculate the
equivalent duct length:
1 Compute the length of all straight ducting.
2 Compute the equivalent duct length of all elbows,
transitions and caps.
3 Add equivalent lengths for all sections of the duct run.