A.O. Smith T-H3S-DV Installation Manual And Owner's Manual page 18

This is a Category IV appliance and must be vented accordingly. The vent system must be sealed airtight.
All seams and joints without gaskets must be sealed with high heat resistant silicone sealant or UL listed
aluminum adhesive tape having a minimum temperature rating of 160 °F. For best results, a vent system
should be as short and straight as possible.
• The Indoor models are a Category IV appliance and must be vented accordingly with any 4" vent
approved for use with Category III/IV or Special BH type gas vent.
• The manufacturer recommends the NovaVent line. However, the following are also UL listed
manufacturers: ProTech Systems Inc. (FasNSeal), Metal-Fab Inc., and Heat-Fab Inc. (Saf-T Vent).
• Follow the vent pipe manufacturer's instructions when installing the vent pipe.
• The maximum length of exhaust vent piping must not exceed 100 ft. (30.5 m) (deducting 5 ft. (1.5
m) for each elbow used in the venting system). Do not use more than 5 elbows.
• When the horizontal vent run exceeds 5 ft. (1.5 m), support the vent run at 3 ft. (0.9 m) intervals
with overhead hangers.
Diameter
4 in. (102 mm)
*For each elbow added, deduct 5 ft. (1.5 m) from max. vent length.
No. of Elbows
0
1
2
3
4
5
Excludes vent terminators, termination elbows, or rain caps.
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-Exhaust vent (Stainless steel vent)-
Max. No. of Elbows Max. Vertical and Horizontal (Total) Vent Length
5
Max. Vertical or Horizontal Vent Length
18
100 ft. (30.5 m )
100 ft. (30.5 m)
95 ft. (29.0 m)
90 ft. (27.4 m)
85 ft. (25.9 m)
80 ft. (24.4 m)
75 ft. (22.9 m)
Page
Installation Manual
Installation