14 Servicing should only be performed by a Qualied Service Technician
venTing TableS – Technical venTing daTa

Type b gaS venT

multiple gas fired Tank-Type heaters

When venting multiple tank type heaters

using Type B vent pipe, follow the installation

diagram and tables below which give sizing

and data based upon NfPA 54 ANSI Z223.1.

model bcl381T1206noX
input: 120,000 btu/hr Total vent height (feet)
vent connector size: 6 inches 6 8 10 15 20 30 50 100
input btu/hr rise vent connector diameter (inches)
120,000 1 ft. 6 6 5 5 5 5 5 5
120,000 2 ft. 5 5 5 5 5 5 5 5
120,000 3 ft. 5 5 5 5 5 5 5 5
number of 120 heaters combined input in
Thousands of btu/hr manifold and common vent diameter (inches)
2 240,000 7 7 6 6 6 6 6 6
3 360,000 8 8 7 7 7 6 6 6
4 480,000 9 9 9 8 8 7 7 6
model bcl381T1546noX
input: 154,000 btu/hr Total vent height (feet)
vent connector size: 6 inches 6 8 10 15 20 30 50 100
input btu/hr rise vent connector diameter (inches)
154,000 1 ft. 6 6 6 6 6 6 6 6
154,000 2 ft. 6 6 6 6 6 6 6 6
154,000 3 ft. 6 6 6 6 6 6 6 6
number of 154 heaters combined input in
Thousands of btu/hr manifold and common vent diameter (inches)
2 308,000 7 7 6 6 6 6 6 6
3 462,000 8 8 7 7 7 6 6 6
4 616,000 9 9 9 8 8 7 7 6
model bcl395T1806noX/1996noX
input: 180,000 and 199,000 btu/hr Total vent height (feet)
vent connector size: 6 inches 6 8 10 15 20 30 50 100
input btu/hr rise vent connector diameter (inches)
180,000 1 ft. 7 7 6 6 6 6 6 6
199,000 1 ft. 7 7 7 6 6 6 6 6
180,000 2 ft. 6 6 6 6 6 6 6 6
199,000 2 ft. 7 7 6 6 6 6 6 6
180,000 3 ft. 6 6 6 6 6 6 6 6
199,000 3 ft. 6 6 6 6 6 6 6 6
number of heaters combined input in
Thousands of btu/hr manifold and common vent diameter (inches)
2360,000 8 8 8 7 7 7 6 6
398,000 8 8 8 7 7 7 6 6
3540,000 10 9 9 9 8 8 7 7
597,000 10 9 9 9 8 8 7 7
4720,000 12 12 10 10 9 9 8 8
796,000 12 12 10 10 9 9 8 8
model (a)bcl395T2506noX
input: 250,000 btu/hr Total vent height (feet)
vent connector size: 6 inches 6 8 10 15 20 30 50 100
input btu/hr rise vent connector diameter (inches)
250,000 1 ft. 8 8 7 7 7 6 6 6
250,000 2 ft. 7 7 7 7 6 6 6 6
250,000 3 ft. 7 7 7 7 6 6 6 6
number of 250 heaters combined input in
Thousands of btu/hr manifold and common vent diameter (inches)
2 500,000 9 9 9 8 8 7 7 7
3 750,000 12 12 10 10 10 9 8 8
4 1,000,000 14 14 12 12 10 10 9 9