DVHVAC36
It is always best to locate the fireplace in such a way that minimizes the number of offsets and horizontal vent length.
The horizontal vent run refers to the total length of vent pipe from the flue collar of the fireplace to the face of the outer wall.
Horizontal plane means no vertical rise exists on this portion of the vent assembly.
For some installations, it may be desirable to have some amount of the horizontal vent run immediately after the fireplace. A vertical rise must be used but can be located anywhere in the vent system, to meet the parameters identified in the venting graph.
•The maximum horizontal vent run is 20' (6 m) when the vertical vent rise is 7¹⁄₂' (2.3 m). (Fig. 18)
| Maximum |
|
Vertical Dimen- | 20 ft. (6.1m) |
|
sion 7¹⁄₂' (2.3m) |
| 48" |
Minimum when | 12" | (1.2m) |
Horizontal Run is | (305mm) |
|
20' (6m) | 15 ft. |
|
|
| |
| (4.6m) |
|
7.5'
(2.3m)
7TDVRT90 Elbow
CFM141
Fig. 18 Maximum number of 90° elbows is three.
•The maximum number of 90° elbows per side wall installation is three (3).
•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.
•When one (1) 90° elbow is installed directly onto another off the back of the fireplace the maximum horizontal vent length is 36" (914 mm). (Fig. 19)
•For each 45° elbow installed in the horizontal run (while maintaining a constant horizontal plane), the length of the horizontal run MUST be reduced by 18" (457 mm). This does not apply if the 45° elbows are installed on the vertical part of the vent system.
•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. 20) This does not apply if the 90° elbows are used to increase or redirect a vertical rise.
14
Example: According to the vent chart the maximum horizontal vent length is 20' (6 m) when the vertical height is 7.5' (2.3 m) from fireplace base height. If one (1) 90° elbow is required in the horizontal vent, it must be reduced to 17' (5.2 m).
•The maximum number of elbow degrees in a sys- tem is 270°. (This does not include transition elbow from rear vent to vertical vent.) (Fig. 21)
Maximum 3' (914mm)
7TDVRT90 Elbow
CFM142
Fig. 19 Maximum horizontal vent run with 90° elbows directly off back of unit.
|
|
| B |
|
|
| 7' |
|
|
| (2.1m) |
A |
|
|
|
10' |
|
|
|
(3m) |
|
|
|
7' 6" | A + B = 17' (5.2m) Max. | ||
(2.3m) |
|
|
|
|
|
| CFM147 |
Fig. 20 Maximum vent run with elbows. | |||
Sample: |
|
| 4 |
Elbow 1 | = | 90° | |
Elbow 2 | = | 45° |
|
Elbow 3 | = | 45° |
|
Elbow 4 | = | 90° |
|
Total angular variation | = | 270° |
|
1 + 2 + 3 + 4 = 270o |
| ||
3 
2
1
CFM132
Fig. 21 Maximum number of elbows.
10001195
