6 For optimum flame appearance and stove performance, keep the vent length and number of elbows to a minimum. The air terminal must remain unobstructed at all times. Examine the air terminal at least once a year to verify that it is unobstructed and undamaged.
SPECIAL INSTALLATION EXAMPLE
When a horizontal offset is required in a 
The maximum horizontal run is 34 inches with a 90° elbow located 29" above the stove. FIGURE 4.
The maximum horizontal run with a 57 inch vertical rise immediately above the stove is 20 feet . Figures 5.
FIGURE 4
In an installation as shown in FIGURE 7, lengths A and C are known based on room height and roof requirements.
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 cal- culated 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 subtracted from this maximum vertical length.
A
B
C
FIGURE 7
FIGS 5
The maximum allowable horizontal run that "B" can be is:
40 ft. (maximum vertical run length)
- 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.
OFFSET INSTALLATION EXAMPLE
FIGURE 8
HORIZONTAL RUN NOT TO EXCEED VERTICAL RISE
If vertical rises greater than 57 inches are necessary, the increased rise must be deducted from the maxi- mum horizontal run.
Use chart, Figure 6, to calculate horizontal runs for vertical rises between 29 and 57 inches.
When calculating maximum run lengths, include 10 feet for each 90° elbow or 5 feet for each 45° elbow.
Do not include the first elbow directly off the unit.
R E Q U I R E D
V E R T I C A L
RISE FROM
FIREPLACE
TO FIRST EL-
BOW IN
INCHES
FIGURE 6
CALCULATED HORIZONTAL VENT RUN IN FEET
If a first run of 72 inches is re- quired, using the "First Vent Run" on the chart shows that a maxi- mum second run of 48 inches is allowable.
IF NECESSARY, THE FIRST RUN AND THE SECOND RUN MAY BE REVERSED.
57"
48" |
| ||
second | run |
| |
| run | ||
first | |||
| |||
72" |
| ||
FIGURE 9
