Alternate Vertical Concentric Venting - Smith XWH 150 Instruction Manual

ALTERNATE VERTICAL CONCENTRIC VENTING

This appliance may be installed with a concentric vent
arrangement where the vent pipe is routed through an existing
unused venting system; or by using the existing unused venting
system as a chase for vent and combustion air routing.
CONCENTRIC VENTING ARRANGEMENT
The venting is to be vertical through the roof. The annular space
between the O.D. of the vent pipe and the I.D. of the existing
unused venting system is utilized for the combustion air source.
The minimum size of the existing vent system required to achieve
enough annular space for combustion air can be found in Table
19 below.
The upper and lower termination as well as any other unsealed
joints in the existing vent system must be sealed to ensure that
all combustion air is drawn from under the vent cap as shown in
Figure's 51 and 52.
Approved venting materials must be used as specified in Table
8 on Page 19.
Follow all vent / air termination and clearance requirements per
this section to the appropriate example. Installation must comply
with local requirements and with the National Fuel Gas Code.
The maximum allowable equivalent vent and air intake lengths
for this venting arrangement are to be determined from the
Venting Installation section.
If an existing unused venting system is converted for use with
this method of concentric venting, the installer must ensure that
the existing venting system is clean and free from particulate
contamination that will harm this appliance and cause increased
nuisance calls or maintenance. Refer to Page 11 for a list of
corrosive contaminants and sources.
Two example scenarios of a concentric venting arrangement are
shown for illustrative purposes in Figure's 51 and 52.
Table 19. Alternate Vertical Concentric Vent / Chase Sizes
MODEL VENT/ AIR
INLET SIZE
150 - 200 3"
285 - 600 4"
700 - 800 6"
Figure 51. Concentric Vent Example 1
MINIMUM EXISTING
VENT / CHASE SIZE
5"
7"
10"
Figure 52. Concentric Vent Example 2
EXISTING VENT AS A CHASE
Follow all existing termination and clearance requirements and
allowable pipe lengths. Use only approved venting materials
listed in the Venting Installation section of this manual.
Figure 53. Existing Vent as a Chase
35