035-17477-002 Rev. D (1202)
22
Unitary Products Group
PIPING ASSEMBLY
The final assembly procedure for the vent piping is as follows:
1.
Cut piping to the proper length, beginning at the furnace.
2.
Deburr the piping inside and outside.
3.
Chamfer the outer edges of the piping.
4.
Dry-fit the entire vent piping system.
5.
Disassemble the piping and apply cement primer and
cement per the cement manufacturer's instructions.
Primer and cement must conform to ASTM D2564 for
PVC, or ASTM D2235 for ABS piping.
6.
All joints must be made to provide a permanent, air tight.
water tight seal.
7.
Support the vent piping such that it is angled 1/4” per lin-
ear foot so that condensate will flow back towards the
furnace. Piping should be supported with pipe hangers to
prevent sagging. Maximum spacing between hangers is
5 feet, except SDR-PVC piping, where maximum spac-
ing is 3 feet.
8.
Seal around the openings where the vent piping passes
through the roof or side wall.
NOTE:
Vent pipe must be sloped 1/4” per foot to allow con-
densate to flow back to the furnace.
METHOD THREE: TWO PIPE SYSTEM USING COM-
BUSTION AIR FROM A VENTILATED ATTIC SPACE
This type installation requires two properly sized pipes. One
brings combustion air from a properly ventilated attic space
and a second pipe from the furnace vent connection (top right
of unit) exits to the outdoors.
COMBUSTION AIR INTAKE
Table 4 on page 15, for intake pipe sizing, allowable length
and elbow usage. Follow all notes, procedures and required
materials in the Two-Pipe Sealed Combustion section
(Method 1) when installing the combustion air pipe within the
unit and into the ventilated attic space.
COMBUSTION AIR TERMINATION
Refer to Figure 30 for required termination method and con-
figuration for the intake pipe. For attic termination, use two 90
elbows with the open end in a downward position. Be sure to
maintain 12" clearance above any insulation, flooring or other
material.
Solvent cements are flammable and must be used
in well-ventilated areas only. Keep them away from
heat, sparks and open flames (including pilots). Do
not breathe vapors and avoid contact with skin and
eyes.
Vent piping must be insulated with 1/2” Armaflex
insulation if it will be subjected to freezing temper-
atures such as routing through unheated areas or
through an unused chimney.
In Canada, refer to CAN/CGA-B149.1 or .2 Installation
Code (latest edition - Venting Systems and Air Supply)
FIGURE 30 :
Attic Combustion Air Termination
Be sure to instruct the owner not to block this
intake pipe.
