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VENT PIPE LENGTH
Size the exhaust outlet and combustion air intake pipes as specified
in Table 1. This table lists the maximum allowable length in feet of
the vent outlet and combustion air inlet pipes as related to the
number of required elbows and the termination (see shaded area).
The specified maximum lengths are for the separate inlet and vent
pipe systems and not the combined length of both systems.
Minimum pipe length is 6 feet.
1.
Determine termination type and pipe size.
2.
Determine number of elbows in exhaust pipe. Do not include
the elbows in the termination. Corresponding number in
shaded area indicates the maximum length of exhaust pipe.
3.
Determine number of elbows in exhaust. Do not include the
elbows in the termination. Corresponding number in shaded
area indicates the maximum length of exhaust pipe.
NOTE: Table 1 used for ABS and PVC material. Table 2 used
for CPVC material.
Example (Using Table I): The desired installation requires a
concentric vent, 2 in. pipe and 3 elbows in the vent outlet piping. 2
elbows are required in the combustion air piping. Referring to the
shaded area of the table, the maximum permissible pipe length for
the vent outlet piping is 44 feet and the maximum permissible pipe
length for the combustion air piping is 48 feet.
When using 2 inch pipe, the inlet and outlet vent length affects the
gas input rate. At maximum vent pipe length, the input will be firing
at approximately 94,000 BTUH. At minimum vent pipe length, the
input will be approximately 100,000 BTUH.
VENT TERMINATION LOCATIONS
The air inlet and vent outlet must be installed with the following minimum
clearances. Refer to Figures 6 and 9.
•
Twelve inches above grade or maximum anticipated snow level.
•
Twelve inches from any opening through which flue gases could enter the
structure.
•
Four feet horizontally and vertically from gas or electric meters, dryer vents,
vent hoods, bathroom fan exhaust, attic fans and turbines.
•
Two feet from an inside corner formed by two exterior walls.
•
Two feet from porches, decks, overhangs and other obstructions.
10
EXHAUST AND INLET AIR PIPING (CONT.)
TABLE I
PIPE
SIZE
IN.
0
1
2
N/A
52
2
N/A
52
2
N/A
44
2
52
48
3
N/A
125
3
N/A
125
3
N/A
115
3
130
120
NOTES:
1. N/A - NOT APPLICABLE
2. THE ABOVE MAXIMUM LENGTHS ARE FOR THE SEPARATE INLET AND OUTLET PIPE SYSTEMS AND NOT THE
COMBINED LENGTH OF BOTH SYSTEMS
3. MAXIMUM OF 6 ELBOWS MAY BE USED PER PIPE. DO NOT COUNT THE ELBOWS IN THE TERMINATION OR THE
CONDENSATE DRAIN ASSEMBLY. ONLY USE MEDIUM OR LONG SWEEP ELBOWS.
4.
TWO 45° ELBOWS ARE CONSIDERED EQUIVALENT TO ONE 90° ELBOW
5.
MINIMUM LENGTH IS 6 FEET PER PIPE.
TABLE 2
PIPE
SIZE
NUMBER OF 90° ELBOWS
IN.
0
1
2
N/A
46
2
N/A
46
2
N/A
26
2
36
26
3
N/A
115
3
N/A
115
3
N/A
95
3
110
95
NOTES:
1. N/A - NOT APPLICABLE
2. THE ABOVE MAXIMUM LENGTHS ARE FOR THE SEPARATE INLET AND OUTLET PIPE SYSTEMS AND NOT THE
COMBINED LENGTH OF BOTH SYSTEMS
3. MAXIMUM OF 4 ELBOWS MAY BE USED PER PIPE EXCEPT WHERE PROHIBITED. DO NOT COUNT THE ELBOWS
IN THE TERMINATION OR THE CONDENSATE DRAIN ASSEMBLY.
4.
TWO 45° ELBOWS ARE CONSIDERED EQUIVALENT TO ONE 90° ELBOW
5.
MINIMUM LENGTH IS 6 FEET PER PIPE.
MAXIMUM ALLOWABLE LENGTH IN FEET OF EXHAUST
AND INTAKE AIR PIPE - ABS AND PVC PIPE AND FITTINGS
NUMBER OF 90° ELBOWS
2
3
4
5
48
44
40
36
48
44
40
36
40
36
32
28
44
40
36
32
120
115
110
105
120
115
110
105
110
105
100
95
115
110
105
100
MAXIMUM ALLOWABLE LENGTH IN FEET OF EXHAUST
AND INTAKE AIR PIPE - CPVC PIPE AND FITTINGS
2
3
4
36
26
16
36
26
16
16
N/A
N/A
16
N/A
N/A
100
85
70
100
85
70
80
65
50
80
65
50
In addition to maintaining the minimum clearances , the vent should terminate
according to the following guidelines:
1. Use only 2 inch pipe on the vent termination. Do not expose any 3" X 2"
reducers or bushings to outdoor ambient temperatures.
2. The air inlet and vent outlet must not terminate under a patio, deck or any
covered area.
3. Do not terminate the vent near walkways or into alleys or other publicly
accessible areas.
4. Do not terminate the vent in an area where children or animals could block
pipes.
5. Do not locate the vent terminal too close to shrubs or bushes as the discharge
and condensate may stunt or kill them.
6. Caulk all cracks, seams and joints within 6 feet horizontally above and below
the vent.
TERMINATION
6
OPTION
32
CONCENTRIC
32
STD. HORIZONTAL
24
ALT. HORIZONTAL
28
VERTICAL
100
CONCENTRIC
100
STD. HORIZONTAL
90
ALT. HORIZONTAL
95
VERTICAL
.
TERMINATION
OPTION
CONCENTRIC
STD. HORIZONTAL
ALT. HORIZONTAL
VERTICAL
CONCENTRIC
STD. HORIZONTAL
ALT. HORIZONTAL
VERTICAL
.
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