Horizontal plane means no vertical rise exists on this portion of the vent assembly.
•The maximum horizontal vent run is 20 ft. (6.1 m) when the vertical vent rise is 7¹⁄₂ ft. (2.3 m). (Fig. 21)
•The maximum number of 90° elbows per side wall installation is three (3).
Vertical Dimension | Maximum |
| |
20 ft. (6.1m) |
| ||
7¹⁄₂’ Minimum When |
| ||
| 48" | ||
Horizontal Run is |
| ||
12" | (1.2m) | ||
20’ | |||
(305mm) |
|
15ft.
(4572mm)
7.5'
(2.3m)
7TDVRT90 Elbow
CFM141
Fig. 21 Maximum number of 90° elbows is three (3).
•If a 90° elbow is used in the horizontal vent run (level height maintained) the maximum horizontal vent length is reduced by 36” (914 mm). (Fig. 22) This does not apply if the 90° elbows are used to increase or redirect a vertical rise. (Fig. 23)
Maximum 3' (914mm)
7TDVRT90 Elbow
CFM142
Fig. 22 Maximum horizontal vent run.
Example: According to the chart the maximum hori- zontal vent length in a system with a 7.5’ (2.3 m) ver- tical rise is 20’ (6 m) and if a 90° elbow is required in the horizontal vent it must be reduced to 17’ (5.2 m). In Figure 23 Dimension A plus B must not be greater than 17’ (5.2 m).
•The maximum number of 45° elbows permitted per side wall installation is two (2). These elbows can be installed in either the vertical or horizontal run.
•For each 45° elbow installed in the horizontal run, the length of the horizontal run MUST be reduced by
LDVR Series Direct Vent Gas Fireplace
7 ft.
(2134 mm)
10 ft.
(3048 mm)
90° Elbow = 3 ft.
A + B = 17 ft. (Max.)
7 ft. 6 in.
(2286 mm)
CFM147
Fig. 23 Maximum vent run with elbows.
18” (45cm). This does not apply if the 45° elbows are installed on the vertical part of the vent system.
•The maximum number of elbow degrees in a system is 270°. (Fig. 24)
Example: |
|
|
|
Elbow 1 | = | 90˚ | 4 |
Elbow 2 | = | 45˚ | |
Elbow 3 | = | 45˚ |
|
Elbow 4 | = | 90˚ |
|
Total angular variation = 270˚
1 + 2 + 3 + 4 = 270o
3 
2
1
CFM132
Fig. 24 Maximum number of elbows.
•IMPORTANT• Minimum clearance between vent pipes and combustible materials is one (1”) inch (25 mm) on bottom, sides and top.
Twist Lock Vent Starter Kit 7TDVSK, plus Transition Elbow 7TDVRT90 must be used in Vertical Sidewall installations. The 4” pipe must be centered inside the 7” pipe coming off the transition elbow. Canadian & USA Installations:
The venting system must conform with local codes, or in the absence of local codes, with National Fuel Gas Code, ANSI Z223.1/NFPA 54 - latest edition, or CSA B149.1 Installation Code.
Only CFM Corporation venting components specifically approved and labelled for this fireplace may be used.
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