Dacor RV30 - Duct Work Design Tips

9
Equivalent Number of Feet -
Duct Elbows and Transitions
45° elbow
8 Inch
3 feet
3 ¼” X 10
45° elbow
7 feet
45° elbow
10 Inch
2 feet
3 ¼” X 10
90° elbow
15 feet
90° elbow
8 Inch
7 feet
3 ¼” X 10
90° flat elbow
20 feet
90° elbow
10 Inch
5 feet
3 ¼” X 10
to 8” round
transition
4 feet
90° 3 ¼” X 10
to 8” round
transition
25 feet
3 ¼” X 10
to 10” round
transition
4 feet
Roof cap* **
Wall cap with
damper*
**
* Not applicable for REMP series blowers.
** The equivalent lengths of roof and wall caps vary with
model and configuration. For equivalent length, contact the
manufacturer or a qualified HVAC specialist.
Blower
Used
Blower Maximum Duct Straight Length
8 Inch Duct 10 Inch Duct
3 ¼” X 10”
Duct
CABP3
50 feet
(15.2 meters)
40 feet
(12.2 meters)
40 feet
(12.2 meters)
ILHSF8
60 feet
(18.3 meters)
50 feet
(15.2 meters)
50 feet
(15.2 meters)
ILHSF10
70 feet
(21.3 meters)
80 feet
(24.4 meters)
70 feet
(21.3 meters)
REMP3
60 feet
(18.3 meters)
50 feet
(15.2 meters)
50 feet
(15.2 meters)
REMP16
70 feet
(21.3 meters)
80 feet
(24.4 meters)
70 feet
(21.3 meters)
Installation Specifications
Calculating the Maximum Duct Run Length
Do not use duct work that is smaller in cross-sectional •
area than the required duct sizes in the table to the
right.
For best performance, keep the duct run as short as •
possible and never exceed the maximums stated at the
right.
The maximum straight duct length for the raised vent •
system depends on the model of blower used with the
vent system and the number of elbows and transitions
used. The Equivalent Number of Feet for each elbow
and transition (see table) must be subtracted from the
maximum straight length to compensate for wind resis-
tance. To determine the maximum allowable length of
the duct work, subtract all of the equivalent lengths of
the elbows and transitions from the Blower Maximum
Duct Straight Length.
For example, for a raised vent system using 3 1/4” X
10” rectangular duct, two (2) 3 1/4” X 10” 90° elbows, a
3 1/4” X 10” rectangular to 10” round transition with a
REMP16 remote blower:
From the • Blower Maximum Duct Straight Length
table, the maximum length without transitions and
elbows is 60 feet.
The equivalent length of each 90• ° elbow is 15 feet.
The equivalent length of 45• ° elbow is 2 feet.
The equivalent length of the transition is 4 feet.•
The total equivalent length of the above components is: •
15 feet + 15 feet + 4 feet + 2 feet = 36 feet.
The maximum amount of straight duct that can be used •
with a REMP16 and the above components is: 60 feet -
34 feet = 24 feet.