5724452-UIM-A-0619
6
Johnson Controls Ducted Systems
UNIT CONNECTIONS
There are several ways to handle the supply and return air duct
connections. The location and sizing of the connections depends on the
situation and the method best suited to the installation. Upflow,
horizontal, or downflow applications may be used.
The supply air duct must be properly sized by use of a transition to
match the unit opening. Refer to Table 1 for air handler unit inlet and
outlet dimensions.
Duct work that is not designed to match the supply air opening can
cause turbulence inside the plenum. This turbulence can change the
airflow patterns across the electric heater limit switches. If the factory
suggested transition cannot be fabricated, it is recommended that a
block off plate (approximately 8" high and running the full width of the
plenum) be attached to the supply opening. Refer to Figure 8 as a
visual aid. The use of this block off plate enables better air circulation
across the limit switches.
AIR FILTERS
Return air filters are required and must be field supplied. Filtration must
be accomplished external to the unit.
.
SECTION V: ELECTRIC HEATER
INSTALLATION
If the air handler requires electric heat, install the electric heat kit
according to the installation instructions included with the kit. After
installing the kit, mark the air handler nameplate to designate the heat
kit that was installed. If no heater is installed, mark the name plate
appropriately to indicate that no heat kit is installed.
Use only 6HK Revision C or later heat kits, as listed on air handler
name plate and in these instructions. Use data from Tables 4 to 10 for
information on required minimum motor speed tap to be used for
heating operation and maximum over-current protection device
required as listed for combination of air handler and heat kit.
For Upflow, Downflow, and Horizontal left-hand applications, the kits
can be installed without modification.
Field modification is required for Horizontal right-hand airflow applica-
tion only. Follow instructions with heater for modification.
SECTION VI: LINE POWER CONNECTIONS
Power may be brought into the unit through the supply air end of the
unit (top left when unit is vertical) or the left side panel. Use the hole
appropriate to the unit’s orientation in each installation to bring conduit
from the disconnect. The power lead conduit must be terminated at the
electrical control box. To determine proper wire sizing, refer to Table 3,
Tables 8 to 11, and the latest edition of the National Electrical Code or
the Canadian Electrical Code as relevant and local codes. To minimize
air leakage, seal the wiring entry point at the outside of the unit.
All electrical connections to air handlers must be made with copper
conductors.
Direct connection of aluminum wiring to air handlers is
not approved.
If aluminum conductors are present, all applicable local and national
codes must be followed when converting from aluminum to copper
conductors prior to connection to the air handler.
The chosen conductor and connections all must meet or exceed the
amperage rating of the overcurrent protector (service disconnect or
fuse) in the circuit.
Additionally, existing aluminum wire within the structure must be sized
correctly for the application according to National Electrical Code and
local codes. Caution must be used when sizing aluminum rather than
copper conductors, as aluminum conductors are rated for less current
than copper conductors of the same size.
FIGURE 8:
Duct Work Transition
CAUTION
Use 1/2” screws to connect duct work to unit. Longer screws will
pierce the drain pan and cause leakage. If pilot holes are drilled, drill
only though field duct and unit bottom duct flange.
CAUTION
Equipment should never be operated without a filter.
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NOTICE
In some horizontal applications, the service disconnects on the elec-
tric heat kits must be rotated 180° so the up position of the discon-
nect is the ON position. This service disconnect orientation change is
required by UL1995, Article 26.19 (in reference to all circuit break-
ers).
