Instructions / Assembly
®
System1738 Installation Methods24
Install Considerations
Universal Concentric Vent Kits (UCVK
TM
) Include:
Dimension (Inches)
A B* C
Nominal Pipe Size
F G
Material Concentric Kit Item # D E
1738 PVC 3” x 24” 397256 31 20 4.5 3 3 2.25 8.75
TABLE 6
B* Dimension be may be shortened to a minimum of 12". Inner pipe (item 
3) must remain 2 inches longer than the outer pipe (item 4). Cut pipe ends 
square and solvent weld as outlined in this manual.
C= Installation cut out should be at least 1/2" larger than dimension “C”.
LENGTHENING THE UNITS IS NOT PERMITTED.
Do NOT mix pipe, fittings, cements, or joining methods 
from different manufacturers, this can result in unsafe 
conditions and will void the certification and the 
product warranty.
 WARNING
System 1738 Pipe, Fittings, Termination Kits and Cements 
are certified as a system and must be installed as such. 
System 1738 PVC concentric termination kits are made 
from a UL1738 certified PVC compound and are rated to 
a maximum temperature of 149
o
F. 
All termination kits must be located and installed in 
accordance with the installation instructions found in this 
guide and with the local building code and NFPA 54 / 
ANSI Z223.1 National Fuel Gas Code.
1
3 4
2
B
A
F
G
C
E
D
Figure 18
Each Kit Contains:
Item Description
Concentric Vent Casing 
Exhaust Pipe
Intake Pipe
Rain Cap
Concentric Vent Kit Installation Considerations
1.  Kits must be securely fastened to structure, to 
ensure clearance dimensions are maintained. Refer 
to Figures 17 - 20 for installation clearances in 
different installation scenarios.
2.  Straps are field supplied. Use straps, clamps or 
equivalent that will not score or damage the pipe. 
Termination support must allow movement as a 
result of expansion and contraction.
3.  All penetrations must be sealed according to local 
building codes. Caulking for side wall terminations 
and flashing for roof penetrations are typical. Use 
only PVC compatible sealing material. Contact 
the Sealant manufacturer for confirmation on 
compatibility with PVC.
4.  The weight of the concentric kits must be supported 
by the clamps/straps and not by the vent system it 
connects to.
5.  Insulating exhaust piping in unconditioned space 
to prevent freezing may be required by the local 
building code. 
6.  The pipe length of the concentric vent kit can be 
shortened, provided that the cutting and welding 
procedures adhere to the System 1738 guidelines 
outlined in this guide.
 NOTE: THE PIPE LENGTH OF THE CONCENTRIC VENT 
KIT CANNOT BE LENGTHENED.
7.  Pipe lengths and/or fittings shall NOT be solvent 
welded to the socket of the rain cap in order to divert 
or extend the exhaust gas, unless the appliance 
manufacture guidelines confirm that the extra length or 
the changing in direction will not adversely impact the 
flow of flue gas.
1 Universal Concentric Vent Kit Casing
2 Rain Cap
3 Exhaust Vent Pipe (Inner)
4 Fresh Air Intake Pipe (Outer)










