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HORIZONTAL VENTING
NOTE -
Common venting is not allowed when horizontally
venting the unit heater.
NOTE -
Precautions must be taken to prevent degradation
of building materials by flue products.
If the unit heater is to be horizontally vented, a positive
pressure may be created in the vent. The unit heater,
when installed with horizontal venting, will perform as a
category III appliance.
1 - In residential applications which vent horizontally,
use only special vent materials approved for use
with Category III appliances.
2 - The vent pipe diameter for horizontal installations
shall be 5” (127mm) diameter on 125K, 150K, 175K,
200K, 250K, & 300K Btuh units and 6” (152mm) on
350K & 400K Btuh units. A flue transition piece is
required to fit over the outlet of the induced draft
assembly on the appliance. A combustion air inlet
flange connector (supplied) is required to fit over the
inlet of the combustion air intake box. See table 3 for
intake and exhaust pipe sizes.
3 - The minimum horizontal vent length is 5 feet (2m).
4 - Refer to table 4 for maximum horizontal vent lengths.
5 - If possible, do not terminate the horizontal vent through
a wall that is exposed to prevailing wind. Exposure
to excessive winds can affect unit performance. If
such a termination is necessary, use a wind block to
protect the vent termination from direct winds.
6 - Vent terminations must be free from obstructions
and at least 12” (305mm) above grade level and
maximum snow height.
7 - Do not install a horizontal vent termination directly below
roof eaves or above a public walkway, or any other
area where condensate dripping may be troublesome
and may cause some staining. Avoid windows where
steam may cause fogging or ice buildup.
8 - Minimum clearance for horizontal vent termination
from any door, window, non-mechanical air supply
inlet is 4 feet below or to the side of opening; 1
foot above opening horizontally for United States
installations. In Canada, minimum clearance for
horizontal vent termination from any door, window,
non-mechanical air supply inlet or the combustion
air inlet to any other appliance is 12 inches for
appliances >10,000 to 100,000 Btuh, and 36 inches
for appliance >100,000 Btuh.
9- Vent terminal clearance to each side of a centerline
extended above a meter/regulator assembly and
service regulator vent outlet must be in accordance
with local installation codes and the requirements of
the gas supplier for installations in the United States.
In Canada the clearance to each side of a centerline
extended above meter/regulator assembly and
service regulator vent outlet must be 3 feet(1m) within
a height 15 feet above the meter/regulator assembly
and 3 feet to a service regulator vent.
Refer to latest editions of the ANSI Z223.1 or CSA-B149
for installation compliance codes and with local author-
ities with jurisdiction.
10 -
Vent termination clearance to an unvented soffit or
within 2 feet horizontally of a ventilated soffit must
be in accordance with local installation codes and
the requirements of the gas supplier.
11 - When a vent termination is inside a corner formed
by two exterior walls the clearance must be in
accordance with local installation codes and the
requirements of the gas supplier.
12 - Vent termination must be a minimum of 3 feet(1m)
above any forced air inlet (includes fresh air inlet
for other appliance, such as a dryer) if within 10
feet horizontally for United States installations. In
Canada, vent termination must have 6 feet (2m)
minimum clearance to a mechanical air-supply inlet
of any building.
13 - When termination is routed through combustible
wall, vent termination must be supported using a
firestop to maintain clearances specified on unit
rating plate. Inside edge of vent termination must
be at least 16” (406mm) from outside wall
14 - All horizontal vents which use special vent pipe for
use with Category III appliances must terminate
with an approved Category III tee. Opening end
must face downward.
15 -
For horizontal venting, the vent pipe shall be
supported with hangers no more than 3 feet (1m)
apart to prevent movement after installation.
16 - Select a wall termination point that will maintain 1/4”
(6mm) rise per foot (305mm) slope of horizontal run
of vent pipe.
17 - For upward sloped vent, a condensate tee and
drain must be installed within the first 5 feet (2m)
from the unit heater to protect the appliance. If a
flexible condensate drain line is used, the drain
line must include a loop filled with water to prevent
combustion products from entering the structure. If
the unit is shut down for an extended period of time
and will be exposed to sub-freezing temperatures,
the condensate may freeze.
18 - Select a wall termination point that will maintain 1/4”
rise per foot slope of horizontal run of vent pipe. In
areas where authorities having jurisdiction permit,
a downward slope of maximum 1/4” per foot is also
acceptable. Condensate drainage can be collected
in a tee pipe section (figure 6) with drain loop similar
to one used for upward slope vent, or allowed to
drip through the vent termination, if permitted by
authorities (figure 8).
TABLE 4
MAXIMUM HORIZONTAL VENT CONNECTOR AND
HORIZONTAL VENT PIPE LENGTHS
No. of
Elbows
125, 150, 175, 200, 350, 400
250 & 300
ft
m
ft
m
1
25
7.6
35
10.7
2
20
6.1
30
9.1
3
15
4.6
25
7.6
4
10
3.0
20
6.1
5
5
1.5
15
4.6
6
-
-
10
3.0
7
-
-
5
1.5
Summary of Contents for LS25 Series
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