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Vent Restrictor Sizing Guidelines
The restrictor sizing tables in this section determine the recommended restrictor for your vent configuration. These tables show Ortal's
recommendations only. The Environment, gas type and other factors may affect the best restrictor choice.
How to use the "Recommended Restrictor" tables:
1.
Find the total vertical rise in your vent configuration along the y-axis.
2.
Find the horizontal run in your vent configuration along the x-axis.
3.
Follow the desired rise and run values within the table until they meet. This value is the recommended restrictor size (in
inches) for your vent configuration.
Legend:
X: Vent configuration is not allowed. Power vent required.
0: No restrictor required.
Numbers other than 0: Represents the recommended restrictor (by width).
44'
2.75"
33'
2.75"
30'
2.75"
27'
2.75"
24'
2.75"
21'
2.75"
18'
1.97"
15'
1.97"
12'
1.97"
9'
1.57"
6'
1.18"
3'
0
0'
X
0'
Vent Clearances
The following clearances apply to the vent system regardless of vent manufacturer.
Vent Clearances
Applies to entire circumference when venting is
Sides: 1"
oriented vertically. Clearance is to any material.
*Top: 3"
Applies to venting oriented horizontally or at an angle.
Clearance is to any material.
Bottom:
1"
*Exception:
Wall thimble top clearance to any material is 1".
X
X
X
1.97"
1.97"
1.97"
1.97"
1.97"
1.97"
1.97"
1.97"
1.97"
2.75"
2.75"
1.97"
2.75"
1.97"
1.97"
1.97"
1.97"
1.57"
1.97"
1.97"
1.57"
1.97"
1.57"
1.57"
1.57"
1.18"
1.18"
0
0
0
0
0
0
X
X
X
3'
6'
9'
Ortal 44HH Series
V Minimum = 3 Feet
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
1.57"
1.18"
X
0
1.57"
1.18"
0
1.57"
1.18"
1.18"
1.18"
0
0
0
0
0
0
0
0
X
X
X
X
X
12'
15'
18'
Horizontal Vent Run
Restrictor Sizes:
20mm (0.79")
30mm (1.18")
40mm (1.57")
50mm (1.97")
70mm (2.75")
85mm (3.35")
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
0
X
X
0
X
X
0
0
X
0
0
X
X
X
X
X
X
X
21'
24'
27'
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
30'
33'
31
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