Clearances (Exterior) - A.O. Smith SERIES 120 Service Handbook

INSTALLATION CONSIDERATIONS
Table 2
MINIMUM CLEARANCES TO COMBUSTIBLE SURFACES
"A" - Right Side "B" - Left Side "C" - Back
5" (12.7 cm) 5" (12.7 cm) 5" (12.7 cm)
A, B, and C clearances to non-combustible surfaces is "0" inches. A 20" clearance to cover remains unchanged.

CLEARANCES (EXTERIOR)

The illustration below shows the required clearances for venting units using natural draft venting.
The vent must extend at least 3 feet above the highest point where it passes through a
roof of a building and at least 2 feet higher than any portion of a building within a horizontal
distance of 10 feet (for vents of 12 inches in diameter or less).
Reference: NFPA 54 ANSI Z 223.1.
Figure 6
Servicing should only be performed by a Qualifi ed Service Agent
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