Sterling GG - Manual (Page 17)

17
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 4
Do not damper or add heat recovery devices to the fl ue
piping. Failure to open such a damper prior to operating
the gas unit heater will result in the spillage of fl 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 clearance between the vent pipe and combustible
materials according to vent pipe manufacturer’s
instructions.
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 specifi ed within this manual.
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 inches for 10,000
to 50,000 BTU/Hr
input; 12 inches for
input exceeding
50,000 BTU/Hr. 9 inches (230mm)
for 10,000 to 50,000
BTU/Hr input; 12
inches (305mm)
for input exceeding
50,000 BTU/Hr.
Forced air inlet within 10 ft. 3 feet above 6 feet (1.8m)
Adjoining Building or parapet 10 feet 10 feet (3.04m)
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 feet 1 feet (0.3m)
*Minimum above maximum snow depth, or per local code, whichever is
greater.