Vent Length And No. Of Elbows; Indoor Installation Diagrams - A.O. Smith 910 Installation Manual And Owner's Manual

This is a Category III 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 350 °F (177 °C). For best results, a vent system should be as short
and straight as possible.
This water heater is a Category III appliance and must be vented accordingly with any 5 in. (127 mm) vent
approved for use with Category III or Special BH type gas vent.
Follow the vent pipe manufacturer's instructions when installing the vent pipe.
Do not common vent this appliance with any other vented appliance. (Do not terminate vent into a
chimney. If the vent must go through the chimney, the vent must run all the way through the chimney
with Category III approved or Special BH vent pipe.)
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.
The maximum length of exhaust vent piping must not exceed 50 ft (15.2 m).* Deduct 5 ft (1.5 m) for each
90° elbow used in the venting system. Do not use more than 5 elbows. A 45° elbow is equivalent to 2.5
ft. of vent length.
Standard Vent Terminations
Vent type Diameter
Intake 5 in. (127 mm)
Exhaust 5 in. (127 mm)
*For each 90° elbow added, deduct 5 ft. (1.5m) from max. vent length.
Max. Vertical or Horizontal
No. of Elbows
0
1
2
Excludes elbow termination, rain caps, or the 5 in. (127 mm) Concentric termination.
Hanger
Vertical
condensation
drain**
Backflow
preventer*
*Backflow preventer (Recommended for freezing weather conditions:
36 °F (2 °C) and below).
**Vertical condensation drain must be installed in accordance with
local codes.

-Vent length and No. of Elbows-

Max. No. of Elbows Max. Vertical and Horizontal (Total) Vent Length
5
5
Vent Length
50 ft (15.2 m)
45 ft (13.7 m)
40 ft (12.2 m)

-Indoor installation diagrams-

Single Pipe with Room-Air Intake
Wall
Sidewall vent
17
Page
50 ft (15.2 m )*
50 ft (15.2 m )*
Max. Vertical or Horizontal
No. of Elbows
3 35 ft (10.7 m)
4
5
Roof
Hanger
Vertical
condensation
drain**
Backflow
preventer*
Vent Length
30 ft (9.1 m)
25 ft (7.6 m)
Rain cap
Roof
Fire stop