21
NOTES:
1. Jumper for 1-3 seconds: Factory Test — The defrost interval timing is reduced by a factor of 0.1 seconds/minute based on the positions of DIP
switches SW1 and SW2 (i.e. 90 minutes will be reduced to 9 seconds).
2. Jumper for 5-20 seconds: Forced Defrost — Defrost runs for 30 seconds if DFT2 is open.
AUXILIARY (ELECTRIC) HEAT CONTROL
The 50TCQ 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. 35 and Table 7). 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. 35 — DIP Switch Settings - Defrost Board
Electric Heaters
50TCQ 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. 36-38.
Table 6 — 50TCQ Defrost Board I/O and Jumper Configurations
POINT NAME TYPE OF I/O CONNECTION PIN NUMBER UNIT CONNECTION NOTE
INPUTS
G Fan DI, 24 vac P2-3 CTB-G
Y1 Cool 1 DI, 24 vac P2-5 CTB-Y1
Y2 Cool 2 DI, 24 vac P2-4 CTB-Y2
W1 Heat 1 DI, 24 vac P2-7 CTB-W1
W2 Heat 2 DI, 24 vac P2-6 CTB-W2
R Power 24 vac P3-1 CONTL BRD-8
C Common 24 vac P3-2 CONTL BRD-4
DFT 1 DI, 24 vac DFT-1 to DFT-1 —
DFT 2 DI, 24 vac DFT-2 to DFT-2 —
OUTPUTS
IFO Fan On DO, 24 vac P3-9 REHEAT/HP-2
OF OD Fan On DO, 24 vac OF OFR
RVS1 DO, 24 vac P3-7 to P3-5 — Energize in COOL
RVS2 DO, 24 vac P3-6 to P3-4 — Energize in COOL
COMP 1 DO, 24 vac P3-10 FPT1-REHEAT/HP-6
COMP2 DO, 24 vac P3-8 FPT2-REHEAT/HP-8
HEAT 2 DO, 24 vac E-HEAT TB4-1
COM 24 vac P3-3 TB4-3
CONFIGURATION
Select Jumper 24 vac P1-1 —
2 Compressor 24 vac P1-3 — Use for 50TCQD
SPEED-UP CONFIGURATION
Speed-Up Jumper — JMP17 —
Speed-Up Jumper — JMP18 —
Table 7 — DIP Switch Positions
12 12 12 12 3
1 1 111 On
0 0 0 00Off
30 minutes
(factory default)
60 minutes 90 minutes 120 minutes Fan Delay
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