59SP6A: Installation, Start-up, Operating, Service and Maintenance Instructions
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
44
Table 14 – Deductions from Maximum Equivalent Vent Length - Ft. (M)
NOTE:
1.Use only the smallest diameter pipe possible for venting. Over-sizing may cause flame disturbance or excessive vent terminal icing or freeze-up.
2.NA - Not allowed. Pressure switch will not close, or flame disturbance may result.
3.Vent sizing for Canadian installations over 4500 ft. (1370 M) above sea level are subject to acceptance by the local authorities having jurisdiction.
4.Size both the combustion air and vent pipe independently, then use the larger size for both pipes.
5.Assume the two 45
_
elbows equal one 90
_
elbow. Wide radius elbows are desirable and may be required in some cases.
6.Elbow and pipe sections within the furnace casing and at the vent termination should not be included in vent length or elbow count.
7.The minimum pipe length is 5 ft. (2 M) linear feet (meters) for all applications.
8.Use 3-in. (76 mm) diameter vent termination kit for installations requiring 4-in. (102 mm) diameter pipe.
9.A running Tee in the Combustion Air Pipe adds 0 ft. to the TEVL of the vent length.
A10497
Fig. 51 – Vent Terminations for Ventilated Combustion Air
Recommended Combustion Air Inlet Moisture Trap
Recommended to prevent moisture from trickling into the furnace
vestibule, a trap can be installed in the intake air pipe near the furnace.
To prevent moisture, connecting a drain line to the trap is recommended
as trace amounts of moisture will evaporate into the intake air stream. If
the combustion air inlet is located near a moisture exhaust duct, or there
are other concerns of excessive moisture being drawn into the
combustion air inlet, it is encouraged to connect a drain line to the trap.
The trap can be constructed from a running tee of the same diameter of
the intake air pipe with
EITHER
a removable cap attached to a 6-inch
long pipe connected to the tee or the External Vent Trap Kit to help
prevent contaminants from entering the furnace. See
The External Vent Trap Kit accessory may be used as a trap for the
combustion air inlet pipe if a large amount of moisture must be removed.
The drain line may be connected to the same drain as the furnace
condensate and the evaporator coil condensate line
ONLY
if the inlet air
trap drain and the evaporator coil drain empty into an open segment of
Pipe Diameter (in):
1-1/2
2
2-1/2
3
4
Mitered 90º Elbow
8
(2.4)
8
(2.4)
8
(2.4)
8
(2.4)
8
(2.4)
Medium Radius 90º Elbow
5
(1.5)
5
(1.5)
5
(1.5)
5
(1.5)
5
(1.5)
Long Radius 90º Elbow
3
(0.9)
3
(0.9)
3
(0.9)
3
(0.9)
3
(0.9)
Mitered 45º Elbow
4
(1.2)
4
(1.2)
4
(1.2)
4
(1.2)
4
(1.2)
Medium Radius 45º Elbow
2.5
(0.8)
2.5
(0.8)
2.5
(0.8)
2.5
(0.8)
2.5
(0.8)
Long Radius 45º Elbow
1.5
(0.5)
1.5
(0.5)
1.5
(0.5)
1.5
(0.5)
1.5
(0.5)
Tee
16
(4.9)
16
(4.9)
16
(4.9)
16
(4.9)
16
(4.9)
Concentric Vent Termination
NA
0
(0.0)
NA
0
(0.0)
NA
Standard Vent Termination
0
(0.0)
0
(0.0)
0
(0.0)
0
(0.0)
0
(0.0)
3” (76 mm)
12” (305 mm)
Pipe hangar
Ventilated Combustion Air
intake termination in crawl
space
Ventilated Combustion
Air intake pipe
CRAWL SPACE
ATTIC
highest level of insulation
