Ductwork Planning Guide
General Information:
• The ductwork transports air born pollutants, moisture and very importantly heat out of the building.
• In addition to good ductwork planning and installation, it is vitally important that your fat filter is washed on a
regular basis.
• The length of ductwork and the number of elbows should be kept to a minimum in order not to degrade the efficiency of your range hood.
• Use duct tape to seal all joints and do not use flexible ducting as this not only creates air turbulence but also provides pockets for moisture and fat residue to condense - this poses a serious fire and health hazard . Flexible
ducting effectively double all of the EL’s below.
• Do not under any circumstances use plastic dryer ducting or 4” vent caps
Worksheet for calculating the Effective Duct Length
Duct Components
6” Round Straight
3- 1/4” x 10”
Straight
6” 90 deg Elbow
6” 45 deg Elbow
3- 1/4” x 10”
90 deg Elbow
3- 1/4” x 10”
45 deg Elbow
3- 1/4” x 10”
90 deg Flat Elbow
6” round to 3- 1/4” x
10” transition
3- 1/4” x 10” to 6”
round transition
6” round to 3- 1/4” x
10” 90 deg transition
3- 1/4” x 10” to 6”
round transition elbow
6” round wall cap
damper
3 1/4”x10” wall
cap damper
Round roof cap
EL* Q* TEL*
1
1
15
9
15
9
20
1
5
5
15
30
30
26
Legend:
EL* = Effective Length:
By assigning a penalty value to a particular fitting it is possible to arrive at a very
good approximation of the effective length
of the ducting run.
Q* = Quantity of that component used
TEL* = Total Effective Length
Multiply the EL of each component by the
quantity and total the column - this should
not exceed 100 ft
Your notes:
Round roof vent
Total of all TEL’s
Ductwork Rough Drawing:
With compliments of Sirius Range Hoods Ltd - www.siriushoods.com Tel: 866 528 4987
24