Venting Practices; Exhaust Piping - Lennox G61MPV Service Manual

6 − Promptly apply solvent cement to end of pipe and in-
side socket surface of fitting. Cement should be ap-
plied lightly but uniformly to inside of socket. Take
care to keep excess cement out of socket. Apply sec-
ond coat to end of pipe.
NOTE − Time is critical at this stage. Do not allow prim-
er to dry before applying cement.
7 − Immediately after applying last coat of cement to pipe,
and while both inside socket surface and end of pipe
are wet with cement, forcefully insert end of pipe into
socket until it bottoms out. Turn pipe 1/4 turn during as-
sembly (but not after pipe is fully inserted) to distribute
cement evenly.
NOTE − Assembly should be completed within 20 sec-
onds after last application of cement. Hammer blows
should not be used when inserting pipe.
8 − After assembly, wipe excess cement from pipe at end
of fitting socket. A properly made joint will show a
bead around its entire perimeter. Any gaps may indi-
cate a defective assembly due to insufficient solvent.
9 − Handle joints carefully until completely set.
C− Venting Practices
The thickness of construction through which vent pipes
may be installed is 24" (610mm) maximum and 3/4"
(19mm) minimum. If a G61MPV furnace replaces a furnace
which was commonly 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.
1. Use recommended piping materials for exhaust pip-
ing.
2. Secure all joints so that they are gas-tight using ap-
proved cement.
Suspend piping using hangers at a minimum of every 5
feet (1.52m) for schedule
40 PVC and every 3 feet
(.91m) for ABS−DWV, PVC−
DWV, SPR−21 PVC, and
SDR−26 PVC piping. A suit-
able hanger can be fabri-
cated by using metal or
plastic strapping or a large
wire tie.
3. 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.
4. Isolate piping at the point where it exits the outside wall
or roof in order to prevent transmission of vibration to
the structure.
5. 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 22 and 23)
NOTE − A 2" diameter street ell is strapped to the blower
deck of 60C−110 units. Street ell must be glued directly
into the unit flue collar. See figure 22. A 3" to 2" reducing
ell is strapped to the blower deck of the 60D−135 units. In
upflow or downflow applications, the reducing ell
must be glued directly into the unit flue collar.
1. Choose the appropriate side for venting in upflow or
downflow positions. Exhaust piping exits from the top
of the unit in horizontal air discharge applications.
Glue the field−provided exhaust vent pipe (or provided
street ell or reducing ell in upflow or downflow applica-
tions) to the flue collar. All cement joints should be
made according to the specifications outlined in ASTM
D 2855. Refer to pipe and fittings specifications and
gluing procedures.
Exhaust piping and condensate trap must be
installed on the same side of the unit in upflow and
dowflow applications.
2. All horizontal runs of exhaust pipe must slope back to-
ward unit. A minimum of 1/4" (6mm) drop for each 12"
(305mm) of horizontal run is mandatory for drainage.
Horizontal runs of exhaust piping must be supported ev-
ery 5 feet (1.52m) using hangers.
NOTE − Exhaust piping should be checked carefully to
make sure there are no sags or low spots.
3. On the opposite side of the cabinet, glue the provided
2" vent plug into the unused flue collar.
4. Route piping to outside of structure. Continue with
installation following instructions given in piping ter-
STRAPPING
mination section.
(metal, plastic
or large wire
ties)
Do not discharge exhaust into an existing stack or
stack that also serves another gas appliance. If verti-
FIGURE 21
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.
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.
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IMPORTANT
CAUTION
CAUTION