Vermont Casting BHDT36 - Manual (Page 11)

- 11 -
If a 90 degree elbow is used in the horizon-
tal vent run (level height maintained) the
maximum horizontal vent length is reduced
by 36 inches. Fig. 15. This does not apply if
the 90 degree elbows are used to increase
or redirect a vertical rise.
The maximum number of elbow degrees in a system is
270º.
Sample: 1 - 90º
2 - 45º
3 - 45º
4 - 90º
Total 270º
Fig. 15
HOW TO USE THE VENT GRAPH
1. Determine the height of the centre of the horizontal
vent pipe exiting through the outer wall. Using this
dimension on the Sidewall Vent Graph (Fig. 17),
locate the point it intersects with the slanted graph
line.
2. From the point of this intersection, draw a vertical
line to the bottom of the graph.
3. Select the indicated dimension, and position the
fireplace in accordance with same.
EXAMPLE A:
If the vertical dimension from the floor of the unit is 11
feet (3352mm) the horizontal run to the face of the outer
wall must not exceed 14 feet (4267mm).
EXAMPLE B:
If the vertical dimension from the floor of the unit is 7 feet
(2133mm), the horizontal run to the face of the outer wall
must not exceed 8-1/2 feet (2590mm).
Example: According to the vent chart the maximum
horizontal vent length is 20' when the vertical height is 7.5'
from fireplace base height. If one 90 degree elbow is
required in the horizontal vent it must be reduced to 17'.
Fig. 16
VERTICAL SIDEWALL VENTING GRAPH
(Dimensions in Feet)
SEE PAGE 14 FOR VENTING
REQUIREMENTS FOR SNORKELS.
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
eg: A
eg: B
VERTICAL DIMENSION FROM THE FLOOR OF THE UNIT
TO THE CENTRE OF THE HORIZONTAL VENT PIPE
Fig. 17
90"
2286mm
84"
2134mm
120"
3048mm
90 º elbow=3'