Lennox SLP98DF070XV36B Handbook Download

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Page 38

Venting Practices

FIGURE 22

* See table 21 for allowable pipe.

Piping Suspension Guidelines

NOTE

- Isolate piping at the point where it exits the outside wall or

roof in order to prevent transmission of vibration to the structure.

SCHEDULE 40 PVC --

Support every 5 feet.

all other pipe* --

Support every 3 feet.

Wall

inside

outside

24” maximum
3/4” minimum

Wall Thickness Guidelines

REPLACING FURNACE THAT WAS PART OF A

COMMON VENT SYSTEM

CHIMNEY

OR GAS

VENT

(Check sizing

for water

heater only)

FURNACE

(Replaced

by SLP98)

WATER

HEATER

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 23

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.

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 condensate
collection trap and lines.

Exhaust Piping (Figure 25)

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

NOTE -

Lennox has approved the use of DuraVent

and

Centrotherm manufactured vent pipe and terminations as
an option to PVC. When using the PolyPro

by DuraVent or

InnoFlue

by Centrotherm venting system the vent pipe re

quirements stated in the unit installation instruction – minim
um & maximum vent lengths, termination clearances, etc. –
apply and must be followed. Follow the instructions
provided with

PoyPro by DuraVent and InnoFlue

by Cen

trotherm venting system for assembly or if requirements are
more restrictive. The PolyPro by Duravent and InnoFlue by
Centrotherm venting system must also follow the uninsu
lated and unconditioned space criteria listed in table 26.

The SLP98DFV is installed only as a Direct Vent gas cen
tral 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 23 and 24. Count all elbows inside and outside the
home. Table 23 lists the

minimum

vent pipe lengths per

mitted. Table 24 lists the

maximum

pipe lengths permitted.

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 27.

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 assistance in
sizing vent pipe in these applications.