14
HORIZONTALLY VENTED UNIT HEATERS
(CATEGORY III)
Horizontal venting arrangements are designed to be
used with single wall vent pipe. Horizontal venting
arrangements must terminate external to the building
using either single wall or double wall (Type B) vent. If
single wall vent pipe is used, it must be constructed of
26 gauge galvanized steel or a material of equivalent
duribility and corrosion resistance for the vent system.
For installations in Canada, use pipe constructed from
.025 inch thick aluminum or .018 inch thick stainless
steel. See Figures 7, 8A and 9A for special installation
requirements regarding these venting conditions.
Do not use Type B (double wall)
vent internally within the building on horizontally
vented power vented units!
If double wall venting is used, components which are
UL Listed and approved for Category III positive pressure
venting systems MUST be used.
A Breidert Type L, Fields Starkap, or equivalent vent
cap must be supplied by the customer for each power
vented unit (Canadian units are equipped with the vent
cap). The vent pipe diameter MUST be as specified in
Table 1 (“D” Dia. Flue Opening). All unit sizes are factory
equipped with the required flue size collar; attach in
place (if not mounted to outlet); refer to included vent
collar instruction sheet for additional requirements.
Vent Systems - Termination Clearance Requirements
Minimum Clearances for
Structure
Termination Locations
4 feet below
Door, window or any gravity air inlet
4 feet horizontally
1 foot above
Forced air inlet within 10 ft.
3 feet above
Adjoining building or parapet
6 feet
Adjacent public walkways
7 feet above grade
The venting system for these appliances shall terminate
at least four feet (1.2m) below, four feet (1.2m) horizontal
from, or one foot (0.3m) above any door, window, or
gravity vent air inlet into the building.
The vent terminal must be at least 12 inches (305mm)
from the exterior of the wall that it passes through to
prevent degradation of the building material by flue
gases.
The vent terminal must be at least 3 feet (1m) above
grade, or in snow areas, at least three feet above the
snow line to prevent blockage by snow.
Through the wall vent for these appliances shall NOT
terminate over public walkways, or over an area where
the 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 not exceed 50
feet (15.2m). Equivalent length is the total length of
straight sections PLUS 15 feet (4.6m) for each 90 elbow
and 8 feet (2.44m) for each 45 elbow.
Maintain 6 inches (152mm) between the vent pipe and
combustible materials.
The vent terminal must be installed with a minimum
horizontal clearance of four feet (1.2m) from electric
meters, gas meters, regulators, and relief equipment.
Seal all vent pipe joints and seams to prevent leakage.
Use General Electric RTV-108, Dow-Corning RTV-732
silicone sealant; or 3M #425 aluminum foil tape.The
vent air system must be installed to prevent collection
of condensate. Pitch horizontal pipes downward 1/4 inch
per foot (21mm per meter) toward the outlet for
condensate drainage
Horizontal portions of the venting systems shall be
supported at maximum intervals of four feet (1.2m) to
prevent sagging (in Canada, support at 3 feet (1m)
minimum intervals).
Insulate single wall vent pipe exposed to cold air or
running through unheated areas.
Each unit must have an individual vent pipe and
vent terminal!
Each unit MUST NOT be connected to
other vent systems or to a chimney.
