To Next Page

To Previous Page

Page 31

TABLE 14

Maximum Allowable Exhaust Vent Pipe Length (in ft.)

Without Insulation In Unconditioned Space For

Winter Design Temperatures Single - Stage High Efficiency Furnace

Winter Design

Temperatures

°F (°C)

Vent Pipe

Diameter

Unit Input Size

030 045 070 090 110 135

32 to 21

(0 to -6)

PVC

PP PVC

1-1/2 in.

N/A N/A

25 N/A 20 N/A N/A N/A N/A N/A N/A N/A

2 in. 18 16 31 28 50 48 30 30 N/A N/A

2-1/2 in. 13 N/A 24 N/A 42 N/A 56 N/A N/A N/A

3 in. 9 9 18 18 35 35 47 47 42 42

20 to 1

(-7 to -17)

1-1/2 in. 15 N/A 20 N/A N/A N/A N/A N/A N/A N/A

2 in 9 8 18 16 32 29 30 30 N/A N/A

2-1/2 in. 5 N/A 13 N/A 24 N/A 34 N/A N/A N/A

3 in. N/A N/A 8 8 19 19 26 26 23 23

0 to -20

(-18 to -29)

1-1/2 in. 10 N/A 15 N/A N/A N/A N/A N/A N/A N/A

2 in. 5 3 12 10 22 19 30 27 N/A N/A

2-1/2 in. N/A N/A 7 N/A 15 N/A 22 N/A N/A N/A

3 in. N/A N/A N/A N/A 10 10 16 16 13 13

Refer to 99% Minimum Design Temperature table provided in the current edition of the ASHRAE Fundamentals Handbook.

Poly-Propylene vent pipe (PP) by Duravent and Centrotherm.

NOTE - Concentric terminations are the equivalent of 5' and should be considered when measuring pipe length.

NOTE - Maximum uninsulated vent lengths listed may include the termination(vent pipe exterior to the structure) and cannot exceed 5 linear feet or the

maximum allowable intake or exhaust vent length listed in table 12 or 13 which ever is less.

NOTE - If insulation is required in an unconditioned space, it must be located on the pipe closest to the furnace. See figure31.

Vent length in the table is equivalent length. Each elbow is equivalent to 5ft of straight pipe length and should be included in measuring total pipe length.

FIGURE 31

Conditioned

Space

Unconditioned

Space

Exhaust

Pipe

Intake

Pipe

Conditioned

Space

Pipe Insulation