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Round Pipe Chart: Combustion Air From Inside of Building

This document provides instructions for calculating the required size of combustion air openings and ventilation for a room with a gas appliance based on the room size and BTU rating of the appliance. It specifies that a room of 25 feet by 40 feet by 8 feet tall with a 140,000 BTU appliance would require a metal grill sized at least 12 inches by 12 inches or wooden grill at least 20 inches by 20 inches including at least 35 square inches and 46.667 square inches of opening for outside combustion air respectively. It also provides a chart for determining the required size of round ventilation pipes based on the total square inches of opening needed.

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rexluther
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299 views1 page

Round Pipe Chart: Combustion Air From Inside of Building

This document provides instructions for calculating the required size of combustion air openings and ventilation for a room with a gas appliance based on the room size and BTU rating of the appliance. It specifies that a room of 25 feet by 40 feet by 8 feet tall with a 140,000 BTU appliance would require a metal grill sized at least 12 inches by 12 inches or wooden grill at least 20 inches by 20 inches including at least 35 square inches and 46.667 square inches of opening for outside combustion air respectively. It also provides a chart for determining the required size of round ventilation pipes based on the total square inches of opening needed.

Uploaded by

rexluther
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as XLS, PDF, TXT or read online on Scribd
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Calculating Room Size Total cu. ft.


Length Width Height In room

25 40 8 8000 READ ALL


Insert Numbers Then Hit "Enter" Key INSTRUCTIONS
Additional
Total cu. ft. cu. ft.
Enter Btu's needed needed
140,000 7000 -1000

COMBUSTION AIR FROM INSIDE OF BUILDING


Calculation of square inches of Grill Size 1
square inch for every 2000 BTU's

Using Metal Grill Using Wooden Grill


Square Inches Needed 186.66667 Square Inches Needed 560
Size of Metal Grill needed 13.662601 BY 13.662601 Size of Wooden Grill Needed 23.664319 BY 23.66432
12" x 12" minimum size grill 20" x 20 " minimum size grill

Obtaining Outside Combustion Air


Hole Only ----- Sq. Inches of Hole Needed in ceiling and floor or
Size of Vertical Round Pipe Size without Grill When Using Metal Grill- Size Needed -
wall Without a Grill 12" of top and one 12" of bottom- Air
(one 12" of top & one 12" of bottom) (one 12" of top & one 12" of bottom)
Openings shall not be less than 3 inches
BTU'S

Sq. Inches Hole Size Sq. Inches Grill Size Sq. Inches
140,000 Needed 35 Needed 35 Needed 46.66667
see chart below 5.9160798 BY 5.91608 6.8313005 BY 6.831301
One Permanent Opening Installation
Square Inches of Horizontal Ducts
1 square inch per 3000 BTU's
1 square inch per 2000 BTU's
(1" clearance on Sides & Back & 6" on Front of
appliances) Ducts to be Installed Top & Bottom with Metal Grill

Sq. Inches Sq. Inches


Needed
62.22222 Needed 93.333333
Opening Size 7.8881 BY 7.888106 Duct Size 9.6609178 BY 9.660918

Round Pipe Chart


without a grill

Round Round
Total Square Inches Required Pipe Size Total Square Inches Required Pipe Size
0 thru 7 3" 132.8 thru 153.9 14"
7.1 thru 12.5 4" 154 thru 176.7 15"
12.6 thru 19.6 5" 176.8 thru 201 16"
19.7 thru 28.2 6" 201.1 thru 226.9 17"
28.3 thru 38.5 7" 227 thru 254.4 18"
38.6 thru 50.3 8" 254.5 thru 283.5 19"
50.4 thru 63.6 9" 283.6 thru 314.1 20"
63.7 thru 78.5 10" 314.2 thru 346.3 21"
78.6 thru 95 11" 346.4 thru 380.1 22"
95.1 thru 113 12" 380.2 thru 415.4 23"
113.1 thru 132.7 13" 415..5 thru 452.3 24"

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