Installation
16
GUNE-SVX001A-EN
Venting
Note:
All vertical and horizontal venting arrangements
for Tubular Duct Furnaces are Category III venting.
ANSI now organizes vented appliances into four
categories.
Category I.
Includes non-condensing appliances with
negative vent pressure, like the traditional atmospheric
unit heater.
Category II.
Groups condensing appliances with
negative vent pressure.
Category III.
Appliances are non-condensing and
operate with a positive vent pressure.
Category IV.
Covers condensing appliances with
positive vent pressure.
Venting for Power Vented Duct Furnaces
(Category III)
Important:
All duct furnaces must be vented!
All venting installations shall be in accordance with the
latest edition of Part 7, Venting of Equipment of the
National Fuel Gas Code, ANSI Z223.1, or applicable
provisions of local building codes for power vented units.
Refer to
. For
installations in Canada, see
Canadian Installations,” p. 17
.
Do not damper or add heat recovery devices to the flue
piping. Failure to open such a damper prior to operating
gas unit will result in the spillage of flue gas into the
occupied space.
Vent pipe material must be in compliance with UL 1738 for
installations in the United States, and UL S636 for
installations in Canada. Refer to
for vent
termination clearance requirements.
Through the wall vents for these appliances shall NOT
terminate over public walkways, or over an area where
condensate or vapor could create a nuisance or hazard or
could be detrimental to the operation of regulators, relief
valves, or other equipment.
The vent pipe equivalent length must be 5 feet (1.5 m)
minimum and must not exceed 50 feet (15.2 m).
Equivalent length is the total length of straight sections
PLUS 10 feet (3.05 m) for each 90° elbow, and 4 feet
(1.22 m) for each 45° elbow.
Maintain 6 inches (152 mm) between vent pipe and
combustible materials. A minimum of 12 inches (305 mm)
of straight pipe is required from the venter outlet before
installing an elbow in the vent system. An elbow should
never be attached directly to the venter!
Any run of single wall vent pipe exposed to cold air or
passing through an unheated space must be insulated
with insulation suitable to 550°F (288°C).
The vent system must be installed to prevent collection of
condensate. Vertical vent pipes should be equipped with
condensate drains. Pitch horizontal pipes downward
1/4 inches per foot (2 mm/m) toward outlet for condensate
drainage.
Horizontal portions of the venting system shall be
supported at maximum intervals of 4 feet (1.2 m) to
prevent sagging. In Canada, support at a maximum of
3 feet (1 m) intervals.
Table 6.
Venting categories
Non-Condensing
Condensing
Negative Vent
Pressure
I
II
Positive Vent
Pressure
III
IV
WARNING
Carbon Monoxide Poisoning!
Your venting system must not be blocked by any snow,
snow drifts, or any foreign matter. Inspect your venting
system to ensure adequate ventilation exists at all
time! Failure to follow these instructions could result in
Carbon Monoxide Poisoning (symptoms include
grogginess, lethargy, inappropriate tiredness, or flu-like
symptoms) which could result in death or serious
injury.
WARNING
Combustible Materials!
Failure to maintain proper clearance between the vent
pipe and combustible materials could cause a fire
which could result in death or serious injury or property
damage. Refer to
for proper clearances.
WARNING
Proper Vent Pipe Required!
Never use a pipe of a diameter other than that specified
in
! Never use PVC or other non-metallic
pipe for venting! Failure to follow instructions could
result in death, serious injury, and property damage.
WARNING
Carbon Monoxide!
Never operate duct furnaces without combustion air
and flue gas piping in place. Each unit MUST have an
individual vent pipe and vent terminal per furnace
section! Each unit MUST NOT be connected to other
vent systems or to a chimney. Your venting system
must not be blocked by any snow, snow drifts, or any
foreign matter. Inspect your venting system to ensure
adequate ventilation exists at all times! Failure to
follow these instructions could result in death or
serious injury.
