Venting Practices
Piping Suspension Guidelines
SCHEDULE 40 PVC −− Support every 5 feet. all other pipe* −− Support every 3 feet.
* See table 4 for allowable pipe.
NOTE − Isolate piping at the point where it exits the outside wall or roof in order to prevent transmission of vibration to the structure.
Wall Thickness Guidelines
24" maximum 3/4" minimum
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FIGURE 13
REPLACING FURNACE THAT WAS PART OF A
COMMON VENT SYSTEM
CHIMNEY
OR GAS
VENT
(Check sizing
for water
heater only)
| WATER |
FURNACE | HEATER |
| |
(Replaced |
|
by SLP98) |
|
| OPENINGS |
| (To Adjacent |
| Room) |
If an SLP98 furnace replaces a furnace which was com- monly vented with another gas appliance, the size of the existing vent pipe for that gas appliance must be checked. Without the heat of the original furnace flue products, the existing vent pipe is probably oversized for the single water heater or other appliance. The vent should be checked for proper draw with the remaining appliance.
FIGURE 14
1 − In areas where piping penetrates joists or interior walls, hole must be large enough to allow clearance on all sides of pipe through center of hole using a hanger.
2 − When furnace is installed in a residence where unit is shut down for an extended period of time, such as a vacation home, make provisions for draining conden- sate collection trap and lines.
Exhaust Piping (Figure 16)
Route piping to outside of structure. Continue with installa- tion following instructions given in piping termination sec- tion.
CAUTION
Do not discharge exhaust into an existing stack or stack that also serves another gas appliance. If verti- cal discharge through an existing unused stack is re- quired, insert PVC pipe inside the stack until the end is even with the top or outlet end of the metal stack.
CAUTION
The exhaust vent pipe operates under positive pres- sure and must be completely sealed to prevent leak- age of combustion products into the living space.
Vent Piping Guidelines
The SLP98DFV is installed only as a Direct Vent gas central furnace.
NOTE − In Direct Vent installations, combustion air is taken from outdoors and flue gases are discharged outdoors.
Intake and exhaust pipe sizing −− Size pipe according to tables 6 and 7. Table 6 lists the minimum vent pipe lengths permitted. Table 7 lists the maximum pipe lengths per- mitted.
Regardless of the diameter of pipe used, the standard roof and wall terminations described in section Exhaust Piping Terminations should be used. Exhaust vent termination pipe is sized to optimize the velocity of the exhaust gas as it exits the termination. Refer to table 9.
In some applications which permit the use of several differ- ent sizes of vent pipe, a combination vent pipe may be used. Contact Lennox’ Application Department for assis- tance in sizing vent pipe in these applications.
TABLE 6
MINIMUM VENT PIPE LENGTHS
SLP98DF | MIN. EQUIV. | EXAMPLE | |
MODEL | VENT LENGTH | ||
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070, 090, 110 | 15 ft.* | 5 ft. plus 2 elbows of 2", 2−1/2" | |
or 3" diameter pipe | |||
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*Any approved termination may be added to the minimum equivalent length listed.
NOTE − It is acceptable to use any pipe size which fits within the guidelines allowed in table 7.
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