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Shorting the jumpers for a period of 5 to 20 secs bypasses
the remaining continuous run period and places the unit in
a Forced Defrost mode. If the controlling DFT is closed
when this mode is initiated, the unit will complete a
normal defrost period that will terminate when the
controlling DFT opens or the 10 minute defrost cycle limit
is reached. If the controlling DFT is open when this mode
is initiated, the Defrost cycle will run for 30 secs. Both
modes end at the end of the Defrost cycle.
ELECTRIC HEATERS
548J units may be e quipped with field--installed accessory
electric heaters. The heaters are modular in design, with
heater frames holding open coil resistance wires strung
through ceramic insulators, line--break limit switches and
a control contactor. One or t wo heater modules may be
used in a unit.
DISCONNECT MOUNTING
LOCATION
UNIT BLOCK-OFF
PANEL
OUTDOOR
ACCESS PANEL
INDOOR
ACCESS
PANEL
C08133
Fig. 29 -- Typical Access Panel Location (3 --6 Ton)
Heate r modules are installed in the compartment below
the indoor (supply) fan outlet. Access is through the
indoor access panel. Heater modules slide into the
compartment on tracks along the bottom of the heater
opening. See Fig. 29, Fig. 30 and Fig. 31.
Not all available heat er modules may be used in every
unit. Use only those heater modules that are UL listed for
use in a specific size unit. Refer to the label on the unit
cabinet re approved heaters.
Unit heaters are marked with Heater Model Numbers. But
heaters are ordered as and shipped i n cartons marked with
a corresponding heater Sales Package part number. See
Table 11 for correlation between heater Model Number
and Sales Package part number.
NOTE: The value in position 9 of the part number differs
between the sales package part number (value is 1) and a
bare heater model number (value is 0).
DISCONNECT
MOUNTING
LOCATION
EMT OR RIGID CONDUIT
(FIELD-SUPPLIED)
SINGLE
POINT BOX
CENTER
POST
HEATER
COVERS
HEATER
MOUNTING
BRACKET
HEATER
MODULE
(LOCATION 2)
HEATER
MODULE
(LOCATION 1)
SINGLE POINT
BOX
MOUNTING
SCREW
BRACKET AND
CONDUIT
DRIP BOOT
MAIN
CONTROL
BOX
CONTROL WIRE TERMINAL BLOCK
MANUAL RESET
LIMIT SWITCH
C08134
Fig. 30 -- Typical Component Location
TRACK
FLANGE
C08135
Fig. 31 -- Typical Module Installation
Table 11 – Heater Model Number
Bare Heater Model Number C R H E A T E R 0 0 1 A 0 0
Heater Sales Package PNO
Includes:
Bare Heater
Carton and packing materials
Installation sheet
C R H E A T E R 1 0 1 A 0 0
548J