20
SEPARATED COMBUSTION – CONCENTRIC VENTING
AIR INLET COLLAR
When the unit is to be used in a separated vent system,
the inlet collar located on the top panel of the unit will
be connected to the combustion air intake pipe. This
connection is made by using a field-provided rubber
coupling in the appropriate size for each unit capacity. The
coupling is installed so that air inlet pipe can de detached
from the unit for serviceability purposes.
GENERAL
Concentric venting allows both the intake for combustion air
and the exhaust vent to pass through a single standard roof
or sidewall opening. This is an alternative to the standard
two pipe intake/vent shown in the separated combustion
venting instructions. Follow these instructions as well as the
separated combustion venting instruction for installation of the
intake/vent pipe(s) and all unit heater installation procedures.
IMPORTANT:Concentric venting reduces the
allowable intake/vent piping length by 5 feet (1.5 m)
from that listed in the venting instructions.
Do not operate the unit until the
installation and assembly of the Concentric Vent
Kit and all piping are completed. Failure to follow
this warning could result in fire, personal injury
or death.
The Concentric Vent Kit contains the following parts:
(1) Combustion Air Inlet Cap
(1) Air Inlet Pipe
(1) Flue Pipe
(1) Intake/Vent Concentric “Y”
Figure 13 – Concentric Vent Kit Assembly
Pipe and fittings are required to complete installation
(user supplied). The combustion air and vent pipe fittings
must conform to ANSI and ASTM standards D1785, F891,
D2665, D2241, D2661, or F628. Pipe cement and primer
must conform to ASTM standards D2564 or D2235.
In Canada, construct all combustion air and vent pipes
for this unit of CSA or ULC certified Schedule 40 PVC,
PVC-DWV, or ABS-DWV pipe and pipe cement.
Table 5 – Concentric Vent Kit Component
Dimensions
1. Shipping dimension. This may be field modified by cutting or extending
both the intake and exhaust pipes. 12 inches (305 mm) is the minimum
allowable length and 60 inches (1.5 m) is the maximum allowable length
for this dimension. Only SDR-26 PVC (ASTM D2241) may be used for
extending pipes. Do not extend pipes with Schedule 40 PVC or couplings.
2. This dimension will change if the intake/vent pipes are lengthened
or shortened.
NOTICE: Some local code inspectors are not familiar
with concentric vents. Be sure to check local code
requirements and acceptability prior to installation.
HORIZONTAL SIDEWALL MOUNTING
NOTE: Refer to the following items before horizontal
installation:
• Check INSTALLATION section of this manual for
allowable clearances and locations.
• Refer to Figures 16 and 17 when venting multiple units
using concentric venting.
• Avoid locations with high winds.
• Avoid locations where Concentric Vent Kit is likely to
be damaged.
• Avoid locations where vapors are objectionable, or
may damage the structure, plants or air conditioning
condensing unit.
1. Determine correct concentric vent kit size for the unit
capacity selected.
2. Determine the best location for the concentric vent;
refer to Figures 15, 16 and 17. Also refer to Table 4
for vent termination clearance requirements.
3. When installing multiple units with concentric venting,
refer to the following guidelines:
a. Do not install multiple concentric vent terminations
directly above one another unless separated by
a minimum of 3 feet (0.91 m); see Figure 16.
b. Install multiple concentric vent terminations so
the horizontal distance between the ends of each
air intake is 4 inches (102 mm) or less or greater
than 24 inches (610 mm); see Figure 17. This will
prevent a recirculation of flue gas.
NOTICE: Every Separated Combustion unit to be installed MUST use the factory-available Concentric Vent
Kit. If you do not have this kit, contact the manufacturer ASAP to obtain one prior to installation.
CAT-10069A
ASSEMBLED TERMINAL
FITTING
AIR INLET PIPE
FLUE PIPE
COMBUSTION
AIR INLET CAP
Unit
Size
Intake/Vent
Nom. Pipe Size
Overall
Assembled
Length
1
Intake Pipe
Outside
Diameter
Air Inlet Pipe
Length
2
100
2"
34-3/4"
3-1/2"
19-1/2"
200
3"
39-1/8"
4-1/2"
24"
300/400
4"
57-1/4"
5-9/16"
41"
