Vermont Castings DBT33, Installation Instructions & Homeowner'S Manual

DBT33/DBT36/DBT39 

-12- 

10002789/0

V

ERTICAL

 S

IDEWALL

 A

PPLICATIONS

Since it is very important that the venting system 

maintain its balance between the combustion air 

intake and the ue gas exhaust, certain limita-

tions as to vent congurations apply and must 

be strictly adhered to.

The Vent Graph showing the relationship between vertical and 

horizontal side wall venting will help to determine the various 

dimensions allowable.  

Minimum clearance between vent pipes and 

combustible materials is one 1"(25mm) on top, 

bottom and sides unless otherwise noted.

When vent termination exits through foundations less than 20" 

below siding outcrop, the vent pipe must ush up with the 

siding.  
It is always best to locate the replace 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 ue collar of the replace to the face of the outer 

wall.
Horizontal plane means no vertical rise exists on this portion 

of the vent assembly.
•  The maximum number of 90º elbows per side wall instal-

lation is three (3).  

•  If a 90º elbow is tted directly onto the replace ange 

the maximum horizontal vent run before the termination  

is 36" (914 mm).

•  If a 90º 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 90º elbows are used to increase or redirect a vertical 

rise (Fig. 21).

Example:  According to the chart the maximum horizontal 

vent length in a system with a 7.5' vertical rise is 20' (6 m) 

and if a 90º elbow is required in the horizontal vent it must 

be reduced to 17' (5.2 m).

In Fig. 20 Dimension A plus B must not be greater than 

17' (5.2 m).

•  The maximum number of 45º elbows permitted per side 

wall installation is two (2). These elbows can be installed 

in either the vertical or horizontal run. 

•  For each 45º elbow installed in the horizontal run, the 

length of the horizontal run MUST be reduced by 18" 

(45cm). This does not apply if the  45º elbows are 

installed on the vertical part of the vent system.

•  The maximum number of elbow degrees in a system is 

270º (See Fig. 21).

Example:  In Figure 21

Elbow 1  = 

90º

Elbow 2  = 

45º

Elbow 3  = 

45º

Elbow 4  = 

90º

Total angular variation  =  270º

Fig. 18

Fig. 19

Fig. 20

Fig. 21