Direct Venting - For Btpv Models - A.O. Smith 650A, 740A Installation & Operation Manual

DIRECT VENTING - FOR BTPV MODELS

All exhaust vent terminal, flue reducer, and intake vent terminal
are supplied with any unit intended for direct venting. These
parts must be installed without alteration.
This heater is category III appliance when used in a direct vent
application. All national and local codes pertaining to the
installation of such an appliance must be followed.
Horizontal portions of the exhaust vent system must be installed
with a minimum upward slope of 1/4" (6.35 mm) per foot of
length.
Selkirk metalbestos model PS or G vent is approved for use as
exhaust venting on these models. Model PS is a double-wall
vent with a 1" (25.4 mm) air space between pipes. Model G is a
single-wall variation of model PS for use where combustible
clearance is not a concern, see Table 4.
TABLE 4.
Selkirk Metalbestos Model PS
Clearance to Combustibles
Interior
Exterior
8" diameter PVC or galvanized pipe is approved for use as
intake venting on these models. Class 63, 100, 125, 200, and
schedule 40 pipe may be used for PVC pipe. Intake venting
must be adequately supported to avoid unnecessary stress on
vent hood, venting, or burner.
See Table 5 limitations on venting system design for direct vent
installations.
FIGURE 6.
6" (152.4 mm)
6" (152.4 mm)
Dimension in
Inches (mm)
Flue Outlet Dia.
Flue Reducer Dimension
(Supplied)
Min. Exhaust Vent Dia. Inch (mm)
Min. Intake Vent Dia. Inch (mm)
Maximum Number Of
Elbows, Intake
Maximum Number Of
Elbows, Exhaust
Total Intake Vent
Length, Equiv. Ft.
Total Exhaust Vent
Length, Equiv. Ft.
Note: Barometric draft control is not used in direct vent installations
as the venting system must be sealed.
When calculating the equivalent length of a venting system each
90 elbow is equivalent to 10 feet of straight pipe. Each 45 elbow
is equivalent to 5 feet (1.5 m) of straight pipe. Do not exceed the
maximum number of elbows as shown in Table 5. In no case may
the sum of the straight pipe lengths and the equivalent lengths of
the elbows exceed the valves in Table 5.
VENT TERMINAL LOCATIONS-EXHAUST
See "Horizontal Venting" in this manual for acceptable locations
for exhaust hoods.
VENT TERMINAL LOCATIONS-INTAKE
When considering locations for the intake terminal, bear in mind
that the terminal:
9
TABLE 5.
BTPV
540A -740A
9 (229)
9 x 8
(229 x 203)
8 (203)
8 (203)
90° 4
45° 8
90° 4
45° 8
Max. 75 (23 m)
Min. 3 (1 m)
Max. 75 (23 m)
Min. 6 (1.8)