Form 43471000
Sept 2011
-23-
Multiple Heater Venting (Connections into a Manifold)
Total
vent
height
Connector
rise
VENT SIZING TABLE
VENT SIZING TABLE
VENT SIZING TABLE
VENT SIZING TABLE —
—
—
— Multiple Heater Venting
Multiple Heater Venting
Multiple Heater Venting
Multiple Heater Venting
Number of Heaters
Number of Heaters
Number of Heaters
Number of Heaters
1
1
1
1
2
2
2
2
3
3
3
3
4
4
4
4
5
5
5
5
CB 20
4”
4”
4”
4”
5”
CB 30
4”
4”
4”
5”
5”
CB 40
4”
4”
5”
5”
6”
CB 50
4”
4”
5”
5”
6”
COMMON VENT DIAMETER
COMMON VENT DIAMETER
COMMON VENT DIAMETER
COMMON VENT DIAMETER
(If a size is not available use the next larger size.)
THE ABOVE ILLUSTRATIONS AND TABLE OF VENT SIZES FOR COMMON VENTING OF MULTIPLE HEATERS ARE IN
ACCORDANCE WITH THE NATIONAL FUEL GAS CODE ANSI Z223.1-LATEST EDITION, NFPA 54-LATEST EDITION, EQUIPMENT
VOLUME OF 1988 ASHRAE HANDBOOK, CURRENT CAN/CGA-B149.1/2-M86 INSTALLATION CODE, AND AGA PUBLICATION
NO. 10M5.85 2.5-2 ON FUNDAMENTALS OF GAS APPLIANCE VENTING AND VENTILATION-REVISED BUT ARE NOT A PART OF
THE CSA CERTIFICATION.
B.
B.
B.
B.
INDIRECT VENTING
INDIRECT VENTING
INDIRECT VENTING
INDIRECT VENTING
(UNVENTED HEATERS)
(UNVENTED HEATERS)
(UNVENTED HEATERS)
(UNVENTED HEATERS) —
—
—
— COMMERCIAL AND INDUSTRIAL INSTALLATIONS ONLY
COMMERCIAL AND INDUSTRIAL INSTALLATIONS ONLY
COMMERCIAL AND INDUSTRIAL INSTALLATIONS ONLY
COMMERCIAL AND INDUSTRIAL INSTALLATIONS ONLY —
—
—
— This
heater requires ventilation in the building to dilute the products of combustion and provide fresh air for
efficient combustion. Where unvented heaters are used, gravity or mechanical means shall be provided to
supply and exhaust at least 4 CFM per 1,000 Btu/hr input of installed heaters. Exhaust vents must be
located at the highest point above and in the vicinity of the heaters, and the inlet vents must be located
below the level of the heaters. An exhaust hood (Part #42924000) must be placed on the outlet collar of the
draft inducer or on the existing 4” starting collar when used unvented and must be mounted only in a
must be mounted only in a
must be mounted only in a
must be mounted only in an
n
n
n
upright
upright
upright
upright posit
posit
posit
position
ion
ion
ion and directed towards the reflector body
and directed towards the reflector body
and directed towards the reflector body
and directed towards the reflector body as shown.
as shown.
as shown.
as shown.
Exhaust Hood
-Required for UNVENTED use-
Draft Inducer
(vertical position)
