14
18-CD19D8-18
Installer’s Guide
Furnace
Air
Inlet
Vent
Furnace
Vent
Air
Inlet
(See Note)
NOTE:
BAYVENT200* accessories can be used for inlet and outlet
terminals when the pipes do not exit the structure together.
The following are
EXAMPLES ONLY
:
EX. 1 —
Example 1 shows that the vent may go vertical while the inlet
air may be on any side of the structure. The vent pipe would
decide the maximum equivalent length for the pipe depending
on the furnace and pipe size.
EX. 3 —
Example 3 shows the vent exiting one side of the house while
the inlet air is on the opposite side of the structure. Here the
vent pipe length must be within the allowable 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.
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.) installed on the end to prevent
dust and debris from falling directly into the furnace.
VENT FITTING MATERIAL – PLASTIC
Gas and liquid tight single wall vent fittings, designed for
resistance to corrosive flue condensate, MUST be used
throughout.
Listed in Table 9 are 2", 2-1/2", and 3" size fittings that meet
these requirements. The materials listed are various grades
of PVC and ABS plastic.
PIPE JOINTS: All joints must be fastened and sealed to
prevent escape of combustion products into the building.
NOTE:
It is recommended that the first joints from the furnace be
connected and sealed with high temperature 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 con-
tainer 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. Cham-
fer 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 outside of pipe.
DO NOT ALLOW PRIMER TO DRY BEFORE APPLY-
ING 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.
Furnace
Air
Inlet
Vent
Attic
Vent
(See Note)
Furnace
Air
Inlet
Vent
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). The inlet air coming from the interior of the house
must meet combustion requirements for area, etc., as shown
in the section AIR FOR COMBUSTION AND VENTILA-
TION in this 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), may come from the
attic if the requirements for combustion air are met as shown
in the section AIR FOR COMBUSTION AND VENTILATION.
