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Make-up air direct vent installation, Air requirements – A.O. Smith 960 through 967 User Manual

Page 10

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ВТН S E R V I C E H A N D B O O K

I N S T A L L A T I O N

AIR REQUIREMENTS

MINIMUM AIR FOR COMBUSTION

10 Cubic Feet of Air Per 1000 BTUH

2.5 CU.

FT

EXCESS

AIR

Stoichiometric or theoretical complete combustion requires 10 cubic feet of air per 1000 BTUH of
gas input. The National Fuel Gas Code also recommends an additional 2.5 cu.ft. of “excess air”.

This 12.5 cu.ft. minimum supply air per 1000 BTUH input applies to natural and propane gas mod­
els.

The National Fuel Code also specifies minimum make-up air opening sizes for various building

installations (Ref: NFPA 54, ANSI Z223.1, sec 5.3).

MAKE-UP AIR

Direct Vent Installation

This model is approved for direct venting either horizontally or vertically or conventional venting

horizontal or vertical. Direct venting avoids using room air for combustion and eliminates the need

for additional air intake ducts.

A. O. Smith Water Products Co.
Ashland City, Tennessee © 2004

9

Technical Training Department

TC-044 Revision 6

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