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.
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.
The minimum flue pipe diameters for all
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.
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.
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
I I
W A T E R
H E A T E R
6 1 5 - 8 8 9 - 8 9 0 0
9
NOTE:
Flue gases will form a
white plume in winter.
Plume could obstruct
window view. Flue gas
condensate can freeze
on exterior surfaces or
on the vent cap. Flue
gas condensate can
cause discoloration of
exterior building
surfaces. Adjacent brick
or masonry surfaces
should be protected with
a rust resistant sheet
metal plate.
(FIG. 8) BAROMETRIC DAMPER INSTALLATION
(TABLE C)
FLUE SIZES AND INLET AIR PIPE SIZES
MODEL
FLUE SIZE
DIRECTAIRE
NUMBER
INLET SIZE
CF401
6
”
6
”
CF501
6
”
6
”
CF651
8
”
8
”
CF751
8
”
8
”
CF991
10
”
10
”
CF1261
12
”
12
”
CF1441
12
”
12
”
CF1801
14
”
12
”
CF2071
14
”
12
”
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).
