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6 - The unit may be vented vertically as a single appliance
or in a common vent with other gas-fired 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
specified by ANSI Z223.1 or CSA-B149 installation
compliance codes. The vent must extend at least 5
feet (2m) above the highest connected equipment
flue collar
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If the UH(RS,CM) 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 4” (102mm) diameter on 30 , 45 , 60 ,
75 , 090, 105 , 125 , and 150 Btuh units; 5”
(127mm) diameter on 175 , 200 , 250 , & 300
Btuh units; 6” (152mm) on 350 & 400 Btuh units.
On 175-400 units, a flue transition piece (supplied)
is required to fit 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 affect 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
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.
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 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.
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.- 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.
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)