Vermont Casting 20DVT Twist Lock Pipes, How to Use the Vent Graph, Vertical Sidewall Applications

Brookhaven Direct Vent Gas Fireplace

Twist Lock Pipes

When using CFM Corporation twist-lock pipe it is not necessary to use sealant on the joints. The only areas of the venting system that need to be sealed with high temperature silicone sealant are the sliding joints of any telescopic vent section used in the system.

To join the twist lock pipes together, simply align the beads of the male end with the grooves of the female end, then while bringing the pipe together, twist the pipe until the flange on the female end contacts the external flange on the male end. It is recommended that you secure the joints with three (3) sheet metal screws, however this is not mandatory with twist lock pipe.

To make it easier to assemble the joints we suggest putting a lubricant (Vaseline or similar) on the male end of the twist lock pipe prior to assembly.

Male End Female End

Screw Holes TWL100

Fig. 9 Twist-lock pipe joints.

How to Use the Vent Graph

The vent chart should be read in conjunction with the following vent installation instructions to determine the relationship of the vertical and horizontal dimensions of the vent system.

1.Determine the height of the center of the horizontal vent pipe exiting through the outer wall. Using this dimension on the Sidewall Vent Graph (Fig. 10) locate the point intersecting with 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 fireplace is 11’ (3.4 m) the horizontal run to the face of the outer wall must not exceed 14’ (4.3 m).

Example B:

If the vertical dimension from the floor of the unit is 7’ (2.14 m), the horizontal run to the face of the outer wall must not exceed 8¹⁄₂’ (2.6 m).

30
29
28
27
26
25						Vertical
24					tothe
23
22
21					center of thehorizontalventpipe	dimension fromtheflooroftheunit
7
20
19
18
17
16
15
14
13
			eg:	A
12
11
10
9
8
6	eg:	B
5
4
3

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Horizontal dimension from the outside face of the

wall to the center of the fireplace vent flange

Sidewall vent graph showing the relationship between vertical

and horizontal dimensions for a Direct Vent flue system.

Fig. 10 Sidewall venting graph. (Dimensions in feet)

Vertical Sidewall Applications

Since it is very important that the venting system maintain its balance between the combustion air intake and the flue gas exhaust, certain limitations as to vent configurations apply and must be strictly adhered to.

The Vent Graph shows the relationship between vertical and horizontal side wall venting and will help to deter- mine the various dimensions allowable.

Minimum clearance between vent pipes and com- bustible materials is 1”(25 mm) on top, bottom and sides unless otherwise noted.

When vent termination exits through foundations less than 20” below siding outcrop, the vent pipe must flush up with the siding. 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.

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