1083288-UIM-A-0114
Johnson Controls Unitary Products
25
VENT SYSTEM
This furnace is certified to be installed with one of two possible vent
configurations.
1. Horizontal vent system. This vent system can be installed com-
pletely horizontal or combinations of horizontal, vertical, or offset
using elbows.
2. Vertical vent system. This vent system can be installed completely
vertical or a combination of horizontal, vertical, or offset using
elbows.
VENT APPLICATIONS AND TERMINATION
When selecting the location for a combustion air / vent termination, the
following should be considered:
1. Observe all clearances listed in vent clearances in these instruc-
tions.
2. Termination should be positioned where vent vapors will not dam-
age plants, shrubs or air conditioning equipment.
3. Termination should be located where it will not be affected by wind
gusts, light snow, airborne leaves or allow recirculation of flue
gases.
4. Termination should be located where it will not be damaged or
exposed to flying stones, balls, etc.
5. Termination should be positioned where vent vapors are not objec-
tionable.
6. Horizontal portions of the vent system must slope upwards and be
supported to prevent sagging.
7. Direct vent systems must be installed so the vent and the combus-
tion air pipes terminate in the same atmospheric zone. Refer to Fig-
ures 28 or 29.
VENTING MULTIPLE UNITS
Multiple units can be installed in a space or structure as either a single
pipe configuration or a two-pipe configuration.
The combustion air side of the single pipe configuration shown in Fig-
ures 27 and 34 is referred to in these instructions as ambient combus-
tion air supply. Follow the instructions for ambient combustion air
installations, paying particular attention to the section on air source from
inside the building. The vent for a single pipe system must be installed
as specified in the venting section of these instructions with both vents
terminating as shown in Figure 27. Each furnace must have a separate
vent pipe. Under NO circumstances can the two vent pipes be tied
together.
The combustion air side of the two-pipe configuration shown in Figures
28 and 29 can be installed so the combustion air pipe terminates as
described in outdoor combustion air or ventilated combustion air sec-
tions in these instructions. Follow the instructions for outdoor combus-
tion air or ventilated combustion air and the instructions for installing the
vent system with the vent terminating as shown in Figure 30 or 31. The
two-pipe system must have a separate combustion air pipe and a sepa-
rate vent pipe for each furnace. Under NO circumstances can the two
combustion air or vent pipes be tied together. The combustion air and
vent pipes must terminate in the same atmospheric zone.
FIGURE 27:
Termination Configuration - 1 Pipe
Condensation in Intake Pipe
Installations where the furnace and intake pipe are to be located in a
conditioned space and in a region that may have hot, humid weather
extending several consecutive days will have condensate form in the
intake pipe. Use of the supplied intake drain will ensure that any con-
densate will be safely diverted away from the internal components of
the furnace. Proper venting installation (of both intake and exhaust)
and sealing any equipment air leaks that might contact the intake pipe
will help reduce condensation.
12” Min.
12” Min.
Maintain 12” minimum clearance
above highest anticipated snow level.
Maximum 24” above roof.
FIGURE 28:
Termination Configuration - 2 Pipe
FIGURE 29:
Termination Configuration - 2 Pipe Basement
Maintain 12” minimum
clearance above
highest anticipated
snow level.
12” vertical separation
between combustion air
intake and vent.
12” minimum
below overhang
12” minimum
separation between
bottom of
combustion air pipe
and bottom of vent.
Maintain 12”
minimum clearance
above highest
anticipated snow
level or grade,
whichever is higher.
12” MIN.
12” MIN.
OVERHANG
12” Minimum
below overhang
12” Minimum
separation between
bottom of
combustion air
intake and
bottom of vent
Maintain 12”
minimumclearance
above highest
anticipated snow
level or grade,
whichever is higher
