44
Furnace Models
(BTU)
FURNACE
INSTALLATION
SINGLE PIPE LENGTH (FT.)
with 1 long radius elbow*
DIRECT VENT,
DUAL PIPE LENGTH (FT.)
with 1 long radius elbow on each pipe*
OUTLET
2” Diameter
OUTLET
3” Diameter
INLET/OUTLET
2” Diameter
INLET/OUTLET
3” Diameter
38,000
Upfl ow
50
70
60
80
54,000
Upfl ow
90
90
90
90
Downfl ow
90
90
90
90
72,000
Upfl ow
90
90
90
90
Downfl ow
90
90
90
90
90,000
Upfl ow
90
90
90
90
Downfl ow
70
90
70
90
108,000
Upfl ow
70
90
60
90
120,000
Upfl ow
N/A
90
N/A
90
Downfl ow
N/A
90
N/A
90
*NOTES:
1. The length of 2” pipe needed to go from the inducer to the fi nish fl ange is 7 3/4” for upfl ow models and 15” for downfl ow
models.
2 Subtract 2.5 ft. for each additional 2 inch long radius elbow, 5 ft. for each additional 2 inch short radius elbow, 3.5 ft. for
each additional 3 inch long radius elbow, and 7 ft. for each additional 3 inch short radius elbow. Subtract 5ft for each 2”
tee and 8ft for each 3” tee.
3. Two 45 degree elbows are equivalent to one 90 degree elbow.
4. This table applies for elevations from sea level to 2,000 ft. For higher elevations, decrease pipe lengths by 8% per 1,000
ft of altitude..
Table 15. Vent Pipe Lengths
**ATTENTION INSTALLERS**
When running the 2” PVC pipe out through the top
of the *SC upfl ow furnace, there may be possible
clearance issues when transitioning the PVC pipe
from 2” to 3”:
• If you have to increase the size of the PVC fl ue from
2” to 3”, you may use two, 2” x 45° PVC elbows to
achieve the clearances needed between the coil
box and the 2x3 coupling (see Figure 30).
• Install the 2x3 coupling in the vertical run only. If the
coupling is installed horizontally, it will allow water
to build up inside the furnace and cause a lock out
condition.
• To avoid the clearance issue, it is recommended that
the furnace be vented through the left side or the
right side of the cabinet as shown in Figures 25-28
(pages 38-41).
2” x 45
0
PVC
Elbow
2” PVC Pipe
2” x 3” PVC
Coupling
Coil Box
Figure 30. Optional PVC Pipe Installation