Lochinvar COPPER-FIN CW 745 - Manual (Page 10)

8 L o c h i n v a r D E S I G N E R ’ S G U I D E C O P P E R - F I N W A T E R H E A T E R 6 1 5 - 8 8 9 - 8 9 0 0
must be consistent with the National Fuel
Gas Code Z223.1 or in Canada, the latest
edition of CGA Standard B149 Installation
Code for Gas Burning Appliances and
Equipment.
VENTING OPTIONS
Conventional Venting
A conventional venting system utilizes
the natural buoyancy of the heated flue
products to generate a negative draft. This
draft forces flue products to rise vertically
through a rooftop flue termination. The vent
connection is made directly to the top of the
unit and combustion air supplied from the
mechanical room. Properly sizing vent
material and the use of a barometric
damper (when required) will lead to proper
vent operation.
The minimum flue pipe diameters for
Copper-Fin models, utilizing negative draft
venting are as follows:
Size vent material using the “FAN” category
of vent sizing tables in the latest edition of
the National Fuel Gas Code. “FAN” applies
to fan-assisted combustion appliances in
Category I.
Barometric Dampers
A barometric damper is required when draft
exceeds 0.08 inches of negative water
column. When installed and adjusted
properly, a barometric damper will maintain
draft between 0.02 and 0.08
inches of
negative water column ensuring proper
operation.
Multiple unit installations with combined
venting also require barometric dampers to
regulate draft at each unit. Again, the
negative draft must be within the range of
0.02 to 0.08 inches of negative water
column to ensure proper operation.
Lochinvar
(FIG. 7) BAROMETRIC DAMPER INSTALLATION
(TABLE B)
FLUE SIZES AND COMBUSTION AIR PIPE SIZES
MODEL FLUE SIZE
NUMBER
CW 495 6"
CW 645 8"
CW 745 8"
CW 986 10"
CW 1256 12"
CW 1436 12"
CW 1796 14"
CW 2066 14"
NOTE:
A vent system should
never be sized based
only on the vent
connection diameter of
the appliance. For proper
vent design and sizing,
please consult the
National Fuel Gas Code
(ANSI Z223.1).