ASX7-4-Installation Instructions

3
VENTING - GENERAL GUIDELINES
Venting Categories
Non
Condensing Condensing
Negative
Vent I II
Pressure
Positive
Vent III IV
Pressure
The following guidelines apply to all categories to follow.
Table 1
Do not damper or add heat recovery devices to the ue
piping. Failure to open such a damper prior to operating
the gas unit heater will result in the spillage of ue gas
into the occupied space.
Avoid installing units in areas under negative pressure.
When required, a flue vent fan should be installed in
accordance with the instructions included with the fan.
Vent connectors serving Category I and Category
II heaters shall not be connected into any portion of
mechanical draft systems operating under positive vent
pressure.
Maintain 1-inch (25.4mm) clearance between the vent
pipe and combustible materials.
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.
NOTICE: Category II and IV do not apply to equip-
ment specied within this manual.
Vent Systems
Termination Clearance Requirements
Structure/Object
Minimum Clearances
for Termination Locations
USA CANADA
Door, window, or gravity vent
inlet; combustion air inlet for
other appliances
9 in. for 10,000
to 50,000 BTU/Hr
input; 12 in. for
input exceeding
50,000 BTU/Hr.
9 in. (230mm)
for 10,000 to
50,000 BTU/Hr
input; 12 in. (305mm)
for input exceeding
50,000 BTU/Hr.
Forced air inlet within 10 ft. 3 ft. above 6 ft. (1.8m)
Adjoining building or parapet 10 ft. 10 ft. (3.04m)
Adjacent public walkways
7 ft. above
grade
7 ft. (2.1m) above
grade
Electric, gas meters
& regulators
4 ft. horizontal
3 ft. (0.9m)
horizontally from
meter/regulator
assembly. 6 ft. (1.8m),
any direction, from a
gas service regulator
vent outlet
Above grade level* 1 ft. 1 ft. (0.3m)
*Minimum above snow depth, or per local code, whichever is greater.