Stack Design Using Direct Vent Combustion - CleaverBrooks CFC Operation, Service & Parts Manual

2. Stack design using direct vent combustion

Table 3-2 STACK SIZING USING OUTSIDE AIR FOR COMBUSTION (DIRECT VENT COMBUSTION)
DIRECT VENT COMBUSTION AIR
Boiler Stack/Flue
Boiler Connection
CFC 500 6" Standard
CFC 500 6" Standard
CFC750 6" Standard
CFC 750 6" Standard
CFC1000 6" Option
CFC1000 6" Option
CFC1000 8" Standard
CFC1000 8" Standard
CFC1000 10" Option
CFC1000 10" Option
CFC1500 8" Option
CFC1500 8" Option
CFC1500 10" Standard
CFC1500 10" Standard
CFC1500 12" Option
CFC1500 12" Option
CFC1800 10" Option
CFC1800 10" Option
CFC1800 12" Standard
CFC1800 12" Standard
CFC 2500 12" Standard
CFC3300 12" Standard
CFC3300 14" Option
* Each additional 90 elbow equals 5 equivalent feet of ductwork. Flue terminations may add 5-10 feet
to the equivalent length and should also be included in the equivalent length calculation.
** Increasing the diameter of the air intake will reduce the overall pressure drop and thereby allow
longer total vent lengths.
Draft tolerance at boiler flue connection during operation is +/- 0.25" WC.
Part No. 750-263
MAXIMUM ALLOWABLE VENTING LENGTH
Combustion Air Boiler Maximum length of
Intake Duct & Flue/Stack
Connection Size
4" 6"
6" 6"
4" 6"
6" 6"
4" 6"
6" 6"
4" 8"
6" 8"
4" 10"
6" 10"
6" 8"
8" 8"
6" 10"
8" 10"
6" 12"
8" 12"
6" 10"
8" 10"
6" 12"
8" 12"
8" 12"
8" 12"
8" 14"
Section 3 — Stack and Intake Vent Sizing and Installation
Maximum length of
Flue Gas Vent in Air Intake Duct in
Feet* Feet**
75 75
80 80
40 40
50 50
30 30
40 40
50 50
60 60
70 70
80 80
30 30
40 40
40 40
60 60
60 60
80 80
40 40
55 55
50 50
80 80
100 100
55 55
100 100
Direct Vent Flue Connection
Combustion Air Kit Part No.
880-01312 039-01704
880-03736 039-01704
880-01312 039-01704
880-03736 039-01704
880-01312 039-01646
880-03736 039-01646
880-01312 039-01647
880-03736 039-01647
880-01312 039-01705
880-03736 039-01705
880-01313 039-01645
880-02451 039-01645
880-01313 039-01644
880-02451 039-01644
880-01313 039-01688
880-02451 039-01688
880-01313 039-01644
880-02451 039-01644
880-01313 039-01688
880-02451 039-01688
880-02451 039-01688
880-02501 039-01761
880-02501 039-01762
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