Submittal Sheet
FIELD CONTROLS, LLC - CONTRACTOR PRODUCTS DRAFT CONTROLS
Control Size
Nominal Cross-
Sectional Area (Sq. In.)
6" 28
7" 38
8" 50
9" 63
10" 78
12" 113
14" 154
16" 201
18" 255
20" 314
24" 452
28" 616
32" 804
Choosing The Right Size
(Sizing the Control)
Simple rules of thumb to guide size selections:
1. Use a draft control the same size as the flue pipe, that is, a 6" control for a 6" round
pipe, a 12" control for a 12" pipe, etc.
2. For intermediate sizes of smoke pipe, use the next larger size draft control to
provide ample capacity. It is a simple matter to install a round control on a pipe an
inch or so larger or smaller than the control.
3. If the flue pipe or breaching is square, use the round equivalent. For example - on a
14" x 14" breaching use a 14" control. Little flow occurs in the corners of a square
pipe so its capacity is approximately the same as a round pipe of the same diameter.
4. If the breaching is rectangular or oval, compute its cross-sectional area and select a
draft control having the same or a greater nominal cross-sectional area. A breaching
14" high x 10" wide would have a cross-sectional area of 140 square inches. From the
table, select a 14" control with a cross-sectional area of 154 square inches.
5. Where a control larger than 32" is required, use more than one regulator with
combined cross-sectional areas equal to or greater than that of the breaching. When
chimneys are of an unusual height or if the draft to be maintained is either very high or
very low, it is advisable to deviate from the rules of thumb outlined here. Refer to the
larger table.
Diameter of
Flue or
Breeching
If Chimney
Height is
Use This
Size
Control
If Chimney
Height is
Use This
Size
Control
If Chimney
Height is
Use This
Size
Control
4 15' or less 4" 16' or more 5"
5 15' or less 5" 16' or more 6"
6 15' or less 6" 16' or more 7"
7 15' or less 7" 16' or more 8"
8 15' or less 8" 16' or more 9"
9 15' or less 9" 16'-30' 10" 31' or more 12"
10 20' or less 10" 21'-40' 12" 41' or more 14"
11 20' or less 12" 21'-40' 12" 41' or more 14"
12 20' or less 12" 21'-40' 14" 41' or more 16"
13 22' or less 14" 23'-45' 16" 46' or more 18"
14 22' or less 14" 23'-45' 16" 46' or more 18"
15 22' or less 16" 23'-45' 16" 46' or more 18"
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