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21
Auxiliary (Electric) Heat control
The 50HCQ unit can be equipped with one or two auxiliary
electric heaters, to provide a second stage of heating. The DFB
will energize this Heating System for a Stage 2 Heating Com-
mand (heaters operate concurrently with compressor(s) in the
Stage 1 Heating cycle), for an Emergency Heating sequence
(compressors are off and only the electric heaters are ener-
gized) and also during the Defrost cycle (to eliminate a “cold
blow” condition in the space).
Defrost
The defrost control mode is a time/temperature sequence.
There are two time components: The continuous run period
and the test/defrost cycle period. The temperature component
is provided by Defrost Thermostat 1 and 2 (DFT1 and DFT2)
mounted on the outdoor coil.
The continuous run period is a fixed time period between the
end of the last defrost cycle (or start of the current Heating cy-
cle) during which no defrost will be permitted. This period can
be set at 30, 60, 90 or 120 minutes by changing the positions of
DIP switches SW1 and SW2 (see Fig. 31 and Table 4). The de-
fault run period is 30 minutes.
Shorting the jumpers for a period of 5 to 20 seconds 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 seconds. Both modes end at the end of the Defrost
cycle.
Fig. 31 — DIP Switch Settings - Defrost Board
ELECTRIC HEATERS
50HCQ units may be equipped with field-installed accessory
electric heaters. The heaters are modular in design, with heater
frames holding open coil resistance wires strung through ce-
ramic insulators, line-break limit switches and a control con-
tactor. One or two heater modules may be used in a unit.
Heater modules are installed in the compartment below the in-
door (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. 32-34.
Not all available heater 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 for the
list of approved heaters.
Unit heaters are marked with Heater Model Numbers, but heat-
ers are ordered as and shipped in cartons marked with a corre-
sponding heater Sales Package part number. See Table 5 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).
Fig. 32 — Typical Access Panel Location
Fig. 33 — Typical Component Location
Fig. 34 — Typical Module Installation
DISCONNECT MOUNTING
LOCATION
UNIT BLOCK-OFF
PANEL
OUTDOOR
ACCESS PANEL
INDOOR
ACCESS
PANEL
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
TRACK
FLANGE
Summary of Contents for 50HCQD07
Page 4: ...4 Fig 2 Unit Dimensional Drawing 07 08 Size Units ...
Page 5: ...5 Fig 2 Unit Dimensional Drawing 07 08 Size Units cont ...
Page 6: ...6 Fig 3 Unit Dimensional Drawing 09 Size Units ...
Page 7: ...7 Fig 3 Unit Dimensional Drawing 09 Size Units cont ...
Page 24: ...24 Fig 37 Electro Mechanical Control Wiring 50HCQ A07 D07 208 230v 460v 575v ...
Page 25: ...25 Fig 38 Electro Mechanical Control Wiring 50HCQ D07 Tier 2 1 Compressor 208 230v 460v 575v ...
Page 26: ...26 Fig 39 Electro Mechanical Control Wiring 50HCQ 08 09 208 230v 460v 575v ...
Page 27: ...27 Fig 40 Electro Mechanical Power Wiring 50HCQ A07 D07 208 230v 460v 575v ...
Page 28: ...28 Fig 41 Electro Mechanical Power Wiring 50HCQ D07 Tier 2 1 Compressor 208 230v 460v 575v ...
Page 29: ...29 Fig 42 Electro Mechanical Power Wiring 50HCQ 08 09 208 230v 460v 575v ...
Page 30: ...30 Fig 43 PremierLink Wiring Schematic 50HCQ07 09 208 230v 460v 575v ...
Page 31: ...31 Fig 44 RTU Open System Control Wiring ...
Page 49: ......