with piping of selected diameter and number of elbows. This table applies to the length and num- ber of elbows for each pipe. To use the table, the furnace input rate, the centerline length and the number of elbows on each pipe must be known. Choose the diameter for which the tabulated length is equal to or greater than required.
Proper use of the table is illustrated by the following example:
Example:
An 80,000 Btuh furnace is to be installed in a
Solution:
Consulting Table 5, in the single pipe length column for an 80,000 Btuh furnace, the maxi- mum allowable length of 2" is 60 feet with one elbow. Select
7.5ft. for a maximum installed vent length of
52.5ft.
Condensing furnace combustion products have very little buoyancy, so Table 5 is to be used without consideration of any vertical rise in the piping.
NOTE: Always use the same or larger size piping for combustion air as is used for the exhaust vent.
Vent Pipe Installation
Pipe Routing and Support
Route piping as directly as possible between the furnace and the outdoors and remember that routing affects pipe size requirements per the preceding section. If a two pipe system is used, locate the combustion air intake and the vent exhaust in the same atmospheric pressure zone
-i.e. both must exit the building though the same portion of exterior wall or roof. Vent piping must be sloped upwards not less than 1/4" per foot in the direction from the furnace to the terminal. This is to ensure that any condensate flows back to the furnace (where it can be disposed of through the condensate disposal system).
The quality of outdoor air must also be consid- ered. Be sure that the combustion air intake is not located near a source of solvent fumes or other chemicals which can cause corrosion of the furnace combustion system.
!CAUTION:
Combustion air must not be drawn from a corrosive atmosphere.
APPLICATION | SINGLE PIPE LENGTH (ft.) | DIRECT VENT, DUAL PIPE LENGTH (ft.) | ||||||
| with 1 long radius elbows*. | with 1 long radius elbows on each pipe.* | ||||||
PVC,CPVC or ABS | Outlet | Outlet | Inlet/Outlet | Inlet/Outlet | Inlet/Outlet | |||
SCH. 40 Pipe Size | 2" | 3" | 2" | 2" | 3" | 2" | 3" | 3" |
Models |
|
|
|
|
|
|
|
|
G6RC,D,L | 80 | 150 | 40 | 40 | 50 | 50 | 90 | 90 |
040 |
|
|
|
|
|
|
|
|
Models |
|
|
|
|
|
|
|
|
G6RC,D,L | 60 | 150 | 30 | 30 | 35 | 35 | 90 | 90 |
060 & 080 |
|
|
|
|
|
|
|
|
Models |
|
|
|
|
|
|
|
|
G6RC,D,L | 30 | 150 | 15 | 15 | 25 | 25 | 90 | 90 |
100 & 120 |
|
|
|
|
|
|
|
|
*NOTES
1.Subtract 2.5 ft. for each additional 2" elbow and 3.5 ft. for each additional 3" elbow.
2.Two 45 degree elbows are equivalent to one 90 degree elbow.
3.One short radius elbow is equivalent to two long radius elbows
4.Do not include termination elbows in calculation of vent length
5.This table is applicable for elevations from sea level to 2000 ft. For higher elevations decrease vent pipe lengths by 8% per 1000 ft. of altitude.
6.Only the above pipe materials are approved for use with G6 Condensing Furnaces.
Table 5. Vent Table
15