How To Use The Vent Graph; Venting Guidelines - Heat & Glo MISSION-BAY Owner's Manual

D. How to Use the Vent Graph
1. Measure the distance from the top of appliance to the
center of the 90° elbow. On the graph below, draw a
horizontal line from that measurement on the vertical
axis across until it intersects with the slanted line.
2. From the point of this intersection, draw a vertical line to
the bottom of the graph.
3. The point at which this line meets the bottom line of the
graph is the maximum length of the horizontal run.
Example 1: If the vertical dimension from the top of the
appliance to the center of the 90° elbow is 7 ft. (21m), the
horizontal run to the outer wall flange must not exceed 13
ft.-3 in. (4m).
.
Example 2: If the vertical dimension from the top of the
appliance is 21 ft. (6m), the horizontal run to the outer wall
flange must not exceed 4 ft.-3 in. (1m).
4. Each 90° elbow is equivalent to 3 ft. (914mm) of vent
pipe and each 45° elbow is equivalent to 1 ft. (305mm)
of vent pipe, and must be subtracted from vent pipe
run. A single vertical to horizontal 90° elbow is already
calculated into the allowable 15 ft. (5m) run. Each
additional 90° elbow reduces the maximum horizontal
distance by 3 ft. (914mm).
Example: The use of three elbows would reduce the
allowable horizontal run to 9 ft. (3 - 1 = 2 elbows
x 3 ft. = 6 ft.; 15 ft. max. - 6 ft. = 9 ft. max.)
VERTICAL DISTANCE
FROM APPLIANCE TO THE
90° ELBOW
Figure 5.2
July 12, 2006
40'
38'
36'
34'
32'
100%
30'
28'
26'
24'
EX. 2
22'
20'
18'
16'
14'
12'
10'
EX 1
8'
6'
4'
2'
0'
11" 2' 4'
TOTAL HORIZON TAL RUN TO OUTSIDE OF EXTERIOR WALL (EXCLUDING ELBOWS )
Heat & Glo · Mission Bay · 250-7512F
E. Venting Guidelines
Notes:
• The maximum horizontal vent run is 15 ft. (5m) when the
vertical vent rise is 10 ft. (3m).
• Horizontal sections require a 1/4 in. (6mm) rise for every
12 in. (305mm) of horizontal travel.
• Exterior vent diameter = 6-5/8 in. (168mm); Inner vent
diameter = 4 in. (102mm).
• Horizontal sections require noncombustible support every
3 ft. (914mm) , e.g. wall straps.
• For any vertical termination a minimum of 6 ft. (2m)
vertical must be used.
EXCEPTIONS FOR HORIZONTAL INSTALLATIONS:
*The maximum horizontal vent run is 30 in. (762mm).
*The maximum horizontal vent run with a 45° elbow is
18 in. (457mm).
*No external minimum rise is required.
*The minimum horizontal vent run is 6 in. (152mm).
80-90%
60 - 70%
Closed
50% Closed
6' 8' 10' 12' 14' 15'
(MAX
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