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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, gravity air inlet, gas or
electric meter, regulators, and relief equipment is 4
feet (1m) for United States installations. In Canada,
horizontal vent termination must have a minimum
6-foot horizontal clearance from gas and electric
meters and relief devices.
Refer to latest editions of the ANSI Z223.1 or CSA-B149
for installation compliance codes and with local author-
ities with jurisdiction.
9 - Vent termination must be a minimum of 4 feet (1m)
below, or 4 feet (1m) horizontally, from any sot or
under-eave vent.
10 - Vent must be a minimum of 6 feet (2m) from an
inside corner formed by two exterior walls. If
possible, leave a 10-foot (3m) clearance.
11 - Vent termination must be a minimum of 10 feet (3m)
from any forced air inlet (includes fresh air inlet for
other appliances, such as a dryer).
12 - When termination is routed through combustible
wall, vent termination must be supported using a
restop to maintain clearances specied on unit
rating plate. Inside edge of vent termination must
be at least 16” (406mm) from outside wall
13 - 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.
14 - For horizontal venting, the vent pipe shall be
supported with hangers no more than 3 feet (1m)
apart to prevent movement after installation.
15 - Select a wall termination point that will maintain 1/4”
(6mm) rise per foot (305mm) slope of horizontal run
of vent pipe.
16 - For upward sloped vent, a condensate tee and
drain must be installed within the rst 5 feet (2m)
from the unit heater to protect the appliance. If a
exible condensate drain line is used, the drain
line must include a loop lled 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.
17 - 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 (gure 4) with drain loop similar
to one used for upward slope vent, or allowed to
drip through the vent termination, if permitted by
authorities (gure 5).
6 - The unit may be vented vertically as a single appliance
or in a common vent with other gas-red appliances.
In common venting situations, vent connectors for
other appliances must maintain a 4” (102mm) vertical
separation between the vent connectors. Refer to
common venting tables in the current editions of
ANSI Z223.1 or CSA-B149 installation compliance
codes for proper vent size.
7 - Clearance to combustible material is 6” (152mm)
for single-wall vent material except where a listed
clearance thimble is used. Clearance to combustible
material for type B-1 vent or factory-built chimney is
per manufacturer’s instructions.
8 - The vent connector shall be supported without any
dips or sags. Vertical vents shall be supported in
accordance with their listing and manufacturers’
instructions. All horizontal vent connector runs shall
have a slope up to the vertical vent of at least 1/4”
per foot (1mm per 50mm).
9 - All vertical type B-1 vents, single-wall vertical vents
(commercial applications), or listed chimney lining
systems must be terminated with a UL-listed (or other
equivalent agency) vent cap or listed roof assembly.
10 - The vent must extend at least 3 feet (1m) above
the highest point where it passes through a roof
of a building. The vent must also extend at least 2
feet (1m) higher than any part of a building within a
horizontal distance of 10 feet (3m) unless otherwise
specied by ANSI Z223.1 or CSA-B149 installation
compliance codes. The vent must extend at least 5
feet (2m) above the highest connected equipment
ue collar
HORIZONTAL VENTING
NOTE - Common venting is not allowed when horizontally
venting the unit heater.
If the LF25 unit heater is to be horizontally vented, a posi-
tive 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 4” (102mm) diameter on 30K, 45K, 60K,
75K, 090K, 105K, 125K, and 150K Btuh units; 5”
(127mm) diameter on 175K, 200K, 250K, & 300K
Btuh units; 6” (152mm) on 350K & 400K Btuh units.
On 175-400 units, a ue transition piece (supplied)
is required to t over the outlet of the induced draft
assembly on the appliance.
3 - The minimum horizontal vent length is 5 feet (2m).
4 - Refer to table 3 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 aect unit performance. If
such a termination is necessary, use a wind block to
protect the vent termination from direct winds.
6 - Horizontal vent termination must be free from
obstructions and at least 12” (305mm) above grade
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