AHRI K2WT, Installation, Operating And Service Instructions

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Vii. Venting
E. Assembly of CPVC/PVC Vent Systems (continued)
Warning
Asphyxiation Hazard. Failure to follow these instructions could cause products of combustion to
enter the building, resulting in severe property damage, personal injury or death.
Use all CPVC vent components (supplied with the boiler) for near-boiler vent piping before
transitioning to Schedule 40 PVC pipe (ASTM 2665) components for remainder of vent system.
Use CPVC vent components within any interior space where air cannot circulate freely, including
through vertical or horizontal chase ways, inside a stud wall, in closets and through wall penetrations.
The use of cellular core PVC (ASTM F891), cellular core CPVC or Radel (polyphenolsulfone is
prohibited.
All condensate that forms in the vent must be able to drain back to the boiler.
Never leave the boiler in operation without the gas sample cap in place (Figure 7.27).
1. The components shown in Table 7.26 are supplied with this boiler for use in a 3” CPVC/PVC vent system. PVC piping must
be supplied by the installer for the air intake pipe and any venting beyond the first 30”.
Quantity Description Size
1 30” Straight CPVC Pipe 3”
1 CPVC Elbow 3”
1 PVC Coupling Termination 3”
1 PVC 90° Elbow Termination 3”
2 Rodent Screen 3”
Table 7.26: CPVC/PVC Vent Kit Components
E. Assembly of CPVC/PVC Vent Systems
2. Assemble the vent system, starting at the boiler:
a. If 3” PVC is to be used for venting, the 3” CPVC elbow and the 30” straight section of CPVC provided with the boiler
must be used before transitioning to PVC. If necessary the 30” straight section of CPVC may be cut in any location and
the CPVC elbow inserted between the two resulting segments.
b. When cutting CPVC or PVC pipe, use a miter saw or a saw designed to cut PVC pipe. Use a miter box or other method to
cut pipe squarely. De-burr both the inside and outside of the cut end.
c. Dry fit all vent components before assembly.
d. The vent adaptor has two different inside diameters. The larger (upper) inside diameter accepts 3” CPVC pipe and is used
in this application (the smaller, lower, inside diameter accepts 3” nominal PolyPro, Polyflue or InnoFlue). A locking ring
in the adaptor prevents the vent pipe from coming out of the adaptor once it is inserted. Lubricate the upper gasket in the
vent adaptor with water and insert the first piece of 3” CPVC into the vent adaptor until it bottoms out.
nOTiCE
Once a vent pipe is inserted into this adaptor, it is IMPOSSIBLE to remove it. Make sure the correct type of
pipe is selected, and that it is of the correct length, before inserting it into the vent adaptor.
e. If 2” CPVC is to be used for the vent system, reduce the first piece of 3” CPVC installed in Step (b) to 2” CPVC using a
CPVC reducing coupling or elbow. Otherwise assemble the 3” CPVC elbow and the remainder of the 30” CPVC piping
before transitioning to PVC. If 3” PVC is used, the first piece of PVC will either be connected to the CPVC elbow
supplied with the boiler, or the end of a section of CPVC vent pipe. In the latter case, a PVC coupling may be used to
connect the first piece of PVC to the last piece of CPVC.
f. Clean all CPVC and PVC components with the appropriate primer before cementing. Cement the vent system together,
starting at the boiler and following the instructions provided on the cans of cement and primer. Use a field supplied
cement and primer that is listed for use with the materials being joined (CPVC and/or PVC). The following, or its
equivalent, may be used to join CPVC to PVC:
• IPS Corporation #P-70 Primer
• IPS Corporation #790 Multi-Purpose Solvent Cement
Always use primer on both the pipe and fitting before applying the cement. Assemble the pipe in accordance with the
instructions on the cans of primer and cement.