Specifications

17
VENTING
ANSI now organizes vented
appliances into four categories.
Venting Categories
Non
Condensing Condensing
Negative
Vent I II
Pressure
Positive
Vent III IV
Pressure
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.
NOTICE: Category II and IV do
not apply to equipment specifi ed
within this manual.
All unit heaters 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 (NFPA54), or applicable provisions of local
building codes. See below for Canadian installations. Refer to Figures 7, 8, 9, 10A, 10B, 11A and 11B.
CARBON MONOXIDE! 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 heed these warnings could result in Carbon Monoxide Poisoning (symptoms include
grogginess, lethargy, inappropriate tiredness, or fl u-like symptoms).
Do not damper or add heat recovery devices to the fl ue piping. Failure to open such a damper prior to operating
gas unit will result in the spillage of fl ue gas into the occupied space.
Vent Systems
Termination Clearance Requirements
Structure/Object
Minimum Clearance
for Termination Locations
USA CANADA
Door, window, or gravity vent
inlet; combustion air inlet for
other appliances
9 inch for 10,000 to
50,000 BTU/Hr
input; 12 inch for
input exceeding
50,000 BTU/Hr.
9 inch (230mm) for
10,000 to 50,000
BTU/Hr input;
12 inch (305mm)
for input exceeding
50,000 BTU/Hr.
Forced air inlet within 10 feet 3 feet above 6 feet (1.8m)
Adjoining Building or parapet 6 feet 6 feet (1.8m)
Adjacent public walkways
7 feet above
grade
7 feet (2.1m) above
grade
Electric, gas meters
& regulators
4 feet horizontal
3 feet (0.9m)
horizontally from
meter/regulator
asembly. 6 feet
(1.8m), any
direction, from
a gas service
regulator vent outlet
Above grade level* 1 foot* 1 foot (0.3m)*
*Minimum above maximum snow depth, or per local code, whichever is
greater.
Table 7
ADDITIONAL REQUIREMENT FOR
CANADIAN INSTALLATIONS
REFER TO SPECIFICATION TABLE AND INSTALLATION MANUAL
FOR PROPER USAGE.
* The following instructions apply to Canadian installations in addition
to installation and operating instructions.
1. Installation must conform with local building codes, or in the absence
of local codes, with current CSA B149.1, Installation Codes for
Natural Gas Burning Appliances and Equipment, or CSA B149.2,
Installation Codes for Propane Gas Burning Appliances and
Equipment.
2. Any reference to U. S. standards or codes in these instructions are to
be ignored, and the applicable Canadian standards or codes applied.