Filter
Top Products
8
W415-0158 / E / 02.19.04
When a horizontal offset is required in a through-the-roof
installation, the following procedure for vent length calcula-
tions must be followed:
In an installation as shown in FIGURES
9 & 12, lengths A and C are known
based on room height and roof require-
ments.
Length C must never be less than 29
inches. Any 90° and 45° elbows must
be calculated as 5 feet of venting
each.
The allowable horizontal run can be
calculated using these parameters. In
this example, the total vertical height is
20 feet (length "A" is required to be 11
feet while length "C" needs to be 9 feet).
The maximum vertical length is 40 feet
and all runs and elbows must be sub-
tracted from this maximum vertical
length.
The maximum allowable horizontal run that "B" can be is:
40 ft. (maximum vertical run length)
-11 ft. (through the roof vertical rise "A")
-10 ft. (2 - 90° elbow)
- 9 ft. (vertical run "C")
10 ft. (maximum allowable horizontal length for "B")
The length of "B" must never be greater than the length
of "A" and "C" combined.
The maximum allowable horizontal run that "A" in Figure 13
can be is:
40 ft. (maximum vertical run length)
- 7 ft. (horizontal run "B")
33 ft. (maximum allowable vertical length for "A")
If a first run of 120 inches is re-
quired, using the "First Vent Run"
on the chart shows that a maxi-
mum second run of 60 inches
is allowable.
IF NECESSARY, THE FIRST
RUN AND THE SECOND
RUN MAY BE REVERSED.
FIGURE 10
FIGURE 11
FIGURE 9
FIGURE 12
FIGURE 13
SPECIAL INSTALLATION EXAMPLE
OFFSET INSTALLATION EXAMPLE