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 (Figures 20 and 21)
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 ML193DF can be installed as either a Non−Direct Vent or a Direct Vent gas central furnace.
NOTE − In
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.
TABLE 6
MINIMUM VENT PIPE LENGTHS
ML193DF | MIN. VENT LENGTH* | |
MODEL | ||
| ||
|
|
| 15 ft. or |
045, 070, 090, 110 | 5 ft plus 2 elbows or |
| 10 ft plus 1 elbow |
|
|
*Any approved termination may be added to the minimum length listed.
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 8.
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.
IMPORTANT
Do not use screens or perforated metal in exhaust or intake terminations. Doing so will cause freeze−ups and may block the terminations.
Use the following steps to correctly size vent pipe diameter.
| 045, 070, |
1 | 090, 110 |
or 135 btuh |
Furnace capacity?
Standard or
2 Which termination?Concentric? See table 5
3 | Which needs | Intake or | |
most elbows? | |||
exhaust | |||
| |||
|
|
4How many?
5 | Desired pipe size? | 2", 2−1/2" |
|
| or 3" |
6What is the altitude?
Use table 7 to find
7max intake or exhaust pipe length.
FIGURE 19
NOTE − It is acceptable to use any pipe size which fits within the guidelines allowed in table 7.
NOTE − All horizontal runs of exhaust pipe must slope back
toward unit. A minimum of 1/4" (6mm) drop for each 12"
(305mm) of horizontal run is mandatory for drainage.
NOTE − Exhaust pipe MUST be glued to furnace exhaust fittings.
NOTE − Exhaust piping should be checked carefully to
make sure there are no sags or low spots.
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