Options & Accessories
800.900.9276 • Fax 800.559.1583 (Customer Service, Service Advisors)
20 Industrial Way, Rochester, NH 03867 • 603.335.6300 • Fax 603.335.3355 (Applications Engineering)
1869 Sismet Road, Mississauga, Ontario, Canada L4W 1W8 • 905.238.0100 • Fax 905.366.0130
www.Laars.com
Document 1427-BW
Common Venting for Brute
pg 5 of 7
3
Number
of Units
Total
Input
(Btu/h)
Max. Equivalent
Vent Length (ft)
6" Trunk
8" Trunk
2
420,000
100
100
3
630,000
100
100
4
840,000
100
100
5
1,050,000
65
100
6
1,260,000
46
100
7
1,470,000
34
97
8
1,680,000
26
75
Table 8: Max Equiv Vent Length for BNTH210
Number
of Units
Total
Input
(Btu/h)
Max. Equivalent Vent Length
(ft)
6" Trunk 8" Trunk
10"
Trunk
2
570,000
100
100
100
3
855,000
86
100
100
4
1,140,000
49
100
100
5
1,425,000
32
92
100
6
1,710,000
23
64
100
7
1,995,000
N/A
48
100
8
2,280,000
N/A
37
100
Table 9: Max Equiv Vent Length for BNTH285 & BNTV285
Number
of Units
Total
Input
(Btu/h)
Max. Equivalent Vent Length
(ft)
8" Trunk
10"
Trunk
12"
Trunk
2
798,000
100
100
100
3
1,197,000
95
100
100
4
1,596,000
54
100
100
5
1,995,000
35
100
100
6
2,394,000
25
87
100
7
2,793,000
N/A
64
100
8
3,192,000
N/A
49
100
Table 10: Max Equiv Vent Length for BNTH399 & BNTV399
3
Number
of Units
Total
Input
(Btu/h)
Max. Equivalent
Vent Length (ft)
6" Trunk
8" Trunk
2
420,000
100
100
3
630,000
100
100
4
840,000
100
100
5
1,050,000
65
100
6
1,260,000
46
100
7
1,470,000
34
97
8
1,680,000
26
75
Table 8: Max Equiv Vent Length for BNTH210
Number
of Units
Total
Input
(Btu/h)
Max. Equivalent Vent Length
(ft)
6" Trunk 8" Trunk
10"
Trunk
2
570,000
100
100
100
3
855,000
86
100
100
4
1,140,000
49
100
100
5
1,425,000
32
92
100
6
1,710,000
23
64
100
7
1,995,000
N/A
48
100
8
2,280,000
N/A
37
100
Table 9: Max Equiv Vent Length for BNTH285 & BNTV285
Number
of Units
Total
Input
(Btu/h)
Max. Equivalent Vent Length
(ft)
8" Trunk
10"
Trunk
12"
Trunk
2
798,000
100
100
100
3
1,197,000
95
100
100
4
1,596,000
54
100
100
5
1,995,000
35
100
100
6
2,394,000
25
87
100
7
2,793,000
N/A
64
100
8
3,192,000
N/A
49
100
Table 10: Max Equiv Vent Length for BNTH399 & BNTV399
2.D Example System Sizing
Insert
Screen
Insert
Screen
3' Max
Not Counted Towards Total Length
3'
45'
1/4" per foot Min.
5' Max.
12" Min.
D
W
G
DWG
DWG
R
E
V
TITLE:
S
REV.
SHEET 2 OF 2
D
DWG. NO:SOFTWARE
INTENDED SIZE:
D
C
B
A
B
C
D
1
2
1
8
S
H
D
W
G
N
O
.
1
3
45
6
7
8
7
6
5
4
3 2
BY LAARS HEATING SYSTEMS CO.
THIS DOCUMENT AND THE INFORMATION CONTAINED HEREIN ARE
PROPRIETARY TO LAARS HEATING SYSTEMS CO. AND SHALL NOT BE
REPRODUCED, TRANSFERRED TO OTHER DOCUMENTS, USED OR
DISCLOSED TO OTHERS FOR MANUFACTURING OR ANY OTHER
PURPOSE EXCEPT AS SPECIFICALLY AUTHORIZED IN WRITING
SCALE: NONE
In the example system above, 6 BNTH210 modulating boilers are to be installed with a common vent.
1. Assuming equivalent vent lengths of 8 feet for an 87º elbow and 3 feet for a 45º elbow, the total equivalent
length is 3+45+8+8+3=67 feet.
2. Using table 8, an 8-inch diameter trunk size is selected.
4
Number
of Units
Total
Input
(Btu/h)
Max. Equivalent Vent Length
(ft)
8" Trunk
10"
Trunk
12"
Trunk
2
1,000,000
73
100
100
3
1,500,000
36
100
100
4
2,000,000
20
72
100
5
2,500,000
N/A
47
100
6
3,000,000
N/A
33
100
7
3,500,000
N/A
24
79
8
4,000,000
N/A
N/A
61
Table 11: Max Equiv Vent Length for BNTH500 & BNTV500
3
Number
of Units
Total
Input
(Btu/h)
Max. Equivalent
Vent Length (ft)
6" Trunk
8" Trunk
2
420,000
100
100
3
630,000
100
100
4
840,000
100
100
5
1,050,000
65
100
6
1,260,000
46
100
7
1,470,000
34
97
8
1,680,000
26
75
Table 8: Max Equiv Vent Length for BNTH210
Number
of Units
Total
Input
(Btu/h)
Max. Equivalent Vent Length
(ft)
6" Trunk 8" Trunk
10"
Trunk
2
570,000
100
100
100
3
855,000
86
100
100
4
1,140,000
49
100
100
5
1,425,000
32
92
100
6
1,710,000
23
64
100
7
1,995,000
N/A
48
100
8
2,280,000
N/A
37
100
Table 9: Max Equiv Vent Length for BNTH285 & BNTV285
Number
of Units
Total
Input
(Btu/h)
Max. Equivalent Vent Length
(ft)
8" Trunk
10"
Trunk
12"
Trunk
2
798,000
100
100
100
3
1,197,000
95
100
100
4
1,596,000
54
100
100
5
1,995,000
35
100
100
6
2,394,000
25
87
100
7
2,793,000
N/A
64
100
8
3,192,000
N/A
49
100
Table 10: Max Equiv Vent Length for BNTH399 & BNTV399