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Vent
Air
Inlet
EX. 2 —
Example 2 shows the vent pipe exhausting through the
roof and the inlet air coming from the interior of the
house (See Note 1). The inlet air coming from the inte-
rior of the house must meet combustion requirements
for area, etc., as shown in the section AIR FOR COM-
BUSTION AND VENTILATION in this Installer's
Guide.
Vent
Air
Inlet
(See Note)
EX. 3 —
Example 3 shows the vent exiting one side of the house
while the inlet air is on the opposite side of the struc-
ture. Here the vent pipe length must be within the al-
lowable length for the size of Furnace and size of the
vent pipe. This example demonstrates that the pipes do
not have to exit on the same side of the structure.
Air
Inlet
18-CD25D1-2
Furnace
Furnace
Vent
Furnace
Installer's Guide
EX. 4 —
The inlet air does not have to come from outside the
structure. Example 4 shows the inlet air (See Note 1),
may come from the attic if the requirements for com-
bustion air are met as shown in the section AIR FOR
COMBUSTION AND VENTILATION.
NOTE: If only the flue gas pipe is to the outside of the
structure, a straight section of pipe (long enough to
exit the Furnace cabinet) must be attached to the inlet
air side with an elbow (which is 5 to 10 equiv. ft.) in-
stalled on the end to prevent dust and debris from fall-
ing directly into the Furnace.
Attic
Vent
s
(See Note)
Furnace
NOTE: It is recommended that the first joints from the
Furnace be connected and sealed with high tempera-
ture RTV. This will enable the pipes to be removed later
without cutting.
Be sure to properly support these joints.
BONDING OF PVC
Commercially available solvent cement for PVC must
be used to join PVC pipe fittings. Follow instructions on
container carefully.
Pipe and Fitting – ASTM D1785, D2466, D2661, &
D2665
PVC Primer and Solvent Cement – ASTM D2564
Procedure for Cementing Joints – Ref ASTM D2855
1. Cut pipe square, remove ragged edges and burrs.
Chamfer end of pipe, then clean fitting socket and
pipe joint area of all dirt, grease, moisture or chips.
2. After checking pipe and socket for proper fit, wipe
socket and pipe with cleaner-primer. Apply a liberal
coat of primer to inside surface of socket and out-
side of pipe.
DO NOT ALLOW PRIMER TO DRY BEFORE AP-
PLYING CEMENT.
3. Apply a thin coat of cement evenly in the socket.
Quickly apply a heavy coat of cement to the pipe
end and insert pipe into fitting with a slight twisting
movement until it bottoms out.
Vent
Air
Inlet
13
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