Lennox International Inc. TUA125S Benutzerhandbuch

Page 6 

 

 
 

 

C-Horizontal Venting - General 
Common venting is not allowed with horizontal vent. 
The minimum horizontal vent length is three feet (914mm).  
  1- 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. 

  2- Vent termination must be free from obstructions and at 

least 12" (306mm) above grade level and maximum 
snow height.  

  3-  Do  not  terminate  vent  directly below roof eaves or 

above a 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. 

 

 

4- When horizontally vented, minimum clearance for 

termination from any door, window, gravity air inlet, 
gas or electric meter, regulators, and relief equipment 
is 4 ft. (1.2m) for U.S. installations. Refer to NFPA 
54/ANSI Z223.1 in the U.S.A. and CSA B149.1 and .2 
in Canada or with authorities having local jurisdiction. 
In Canada, vent termination must have a minimum 6 
ft. (1.8mm) horizontal clearance from gas and electric 
meters and relief devices as specified in the Canadian 
B149.1, Natural Gas Installation Code. 

  5- Vent termination must be a minimum of 4' (1.2m) 

below or 4’ (1.2m) horizontally from any soffit vent or 
under-eave vent. 

  6- Vent must be a minimum of 6' from an inside corner 

formed by two exterior walls. If possible, leave a 10' 
clearance. 

  7- Vent termination must be a minimum of 10' (3m) from 

any forced air inlet (includes fresh air inlet for other 
appliances, such as a dryer). 

 

 

8- 

When termination is routed through an exterior 
combustible wall the vent must be supported using a 
listed clearance thimble. Where local authorities 
permit, a single section of type B-1 vent pipe may be 

used as an alternative to the thimble. When using a 
type B-1 vent termination use the clearances specified 
by the vent manufacturer. Seal the connection 
between the single wall and double wall pipes and the 
annular space of the double wall pipe as shown in 
figure 2. Inside edge of vent termination tee or 
Belmont cap must be at least 12 inches from outside 
wall as shown in figure 3. 

  9- All horizontal vents must terminate with a tee or with a 

cap as specified in table 4. Opening end of tee used 
for termination must face downward. Addition of ¼” 
(6mm) mesh corrosion resistant material as a bird 
screen in the tee or cap openings may be used. 

9- For horizontal venting, the vent pipe shall be 

supported with hangers no more than 3ft. (1m) apart 
to prevent movement after installation. 

10- 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. Clearance to 
combustible material is 1” at the sides, 1” below, and 
3” above on horizontal installations of the concentric 
vent/adapter/cap kit 

 

1-  Horizontal commercial installations are for buildings 

that are not attached to living spaces. The vent may 
be single wall vent material installed according to 
the sections Venting 

Recommendations and Requirements and  C-
Horizontal Venting - General and  D-Horizontal 
Venting - Commercial. Refer to figures 3, 4, and 5. 
The air inlet may be single wall vent material or U.L. 
listed single wall flex connector. 

2-  Refer to table 2 for maximum vent lengths. The vent 

pipe diameter for horizontal commercial installations 
shall be 3” (76mm) on 45 units, 4” (100mm) on 
60/75 units, 5” (127mm)on 100/125 units.