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37
Model
Venting
Category
Certified Venting
Material
Vent Size
(inches)
Maximum Vent
Length (feet)
Combustion Air
Intake Pipe
Material
Air Inlet
Size
(inches)
Max. Air
Intake Length
(feet)
ADB-751
w/CHX
IV
UL 1738 Certified
Venting Material e.g.
AL29-4C Stainless
Steel PVC*, CPVC*
8
35
Subtract 10 ft per
elbow, Max. 3
elbows
Galvanized
Steel
PVC, ABS
CPVC
6
35
Subtract 10 ft
per elbow,
Max. 3 elbows
ADB-1001
w/CHX
IV
UL 1738 Certified
Venting Material e.g.
AL29-4C Stainless
Steel PVC*, CPVC*
10
35
Subtract 10 ft per
elbow, Max. 3
elbows
Galvanized
Steel
PVC, ABS
CPVC
6
35
Subtract 10 ft
per elbow,
Max. 3 elbows
ADB-1501
w/CHX
IV
UL 1738 Certified
Venting Material e.g.
AL29-4C Stainless
Steel PVC*, CPVC*
12
35
Subtract 10 ft per
elbow, Max. 3
elbows
Galvanized
Steel
PVC, ABS
CPVC
8**
35
Subtract 10 ft
per elbow,
Max. 3 elbows
*Contact the manufacturer for details.
**If the boiler is direct vented, a 6 to 8 in. adapter must be installed at the blower inlet.
Fig. 27: Horizontal Thru-Wall Direct Venting/Combustion Air with Add-on
Condensing Heat Exchanger (Category IV)
Table Q: Horizontal Thru-wall Direct Venting with Add-on
Condensing Heat Exchanger