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Jumper for 1-3 seconds: Factory Test, defrost runs for 9 seconds
Jumper for 5-20 seconds: Forced Defrost, defrost runs for 30 seconds if
DFT2 is open
Reversing Valve Control
The DFB has two outputs for unit reversing valve control. Op-
eration of the reversing valves is based on internal logic; this
application does not use an “O” or “B” signal to determine re-
versing valve position. Reversing valves are energized during
the cooling stages and the defrost cycle and de-energized
during heating cycles. Once energized at the start of a cooling
stage, the reversing valve will remain energized until the next
heating cycle demand is received. Once de-energized at the
start of a Heating cycle, the reversing valves will remain de-en-
ergized until the next cooling stage is initiated.
Compressor Control
The DFB receives inputs indicating Stage 1 Cooling and Stage
1 Heating from the space thermostat or unit control system
(PremierLink
®
or RTU-OPEN); it generates commands to start
compressors with or without reversing valve operation to pro-
duce Stage 1 Cooling or Stage 1 Heating. The 04-06 systems
have one compressor).
Auxiliary (Electric) Heat Control
The 50KCQ 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 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. 29 and Table 9). The de-
fault run periods are 60 minutes for unit sizes 04-06.
Fig. 29 — DIP Switch Settings - Defrost Board
At the end of the continuous run period, the defrost control will
test for a need to defrost. On unit sizes 04-06 (single compres-
sor designs), DFT1 controls the start and termination of the de-
frost cycle. If DFT1 is still open, the defrost test/run window is
closed and the control repeats the continuous run period. If
DFT1 is closed, the defrost cycle is initiated. The defrost peri-
od will end when DFT1 opens (indicating the outdoor coil has
been cleared of frost and ice) or a 10 minute elapsed period ex-
pires, whichever comes first.
At the end of the unit defrost cycle, the unit will be returned to
Heating cycle for a full continuous run period. If the space
heating load is satisfied and compressor operation is terminat-
ed, the defrost control will remember where the run period was
interrupted. On restart in Heating, the defrost control will re-
sume unit operation at the point in the run period where it was
last operating.
Table 8 — 50KCQ 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
LCTB-G
Y1 Cool 1
DI, 24 vac
P2-5
LCTB-Y1
Y2 Cool 2
DI, 24 vac
P2-4
LCTB-Y2
W1 Heat 1
DI, 24 vac
P2-7
LCTB-W1
W2 Heat 2
DI, 24 vac
P2-6
LCTB-W2
R Power
24 vac
P3-1
CONTL BRD-8
C Common
24 vac
P3-2
CONTL BRD-4
DFT1
DI, 24 vac
DFT-1 to DFT-1
DFT2
DI, 24 vac
DFT-2 to DFT-2
OUTPUTS
IFO Fan On
DO, 24 vac
P3-9
REHEAT
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
FPT-REHEAT-6
COMP 2
DO, 24 vac
P3-8
REHEAT-8
HEAT 2
DO, 24 vac
E-HEAT
HC-1 (TB4-1)
COM
24 vac
P3-3
HC-1 (TB4-3)
CONFIGURATION
Select Jumper
24 vac
P1-1
SPEED-UP CONFIGURATION
Speed-Up Jumper
JMP17
Speed-Up Jumper
JMP18
Summary of Contents for WeatherMaker 50KCQ A04 Series
Page 34: ...34 Fig 53 RTU Open Overlay for Economizer Wiring ...
Page 35: ...35 Fig 54 VFD Overlay for W2770 Controller Wiring ...
Page 70: ...70 Fig C 50KCQ A04 A05 A06 Control Wiring Diagram 575 3 60 APPENDIX D WIRING DIAGRAMS ...
Page 71: ...71 Fig D 50KCQ A04 A05 A06 Power Wiring Diagram 208 230 1 60 APPENDIX D WIRING DIAGRAMS ...
Page 72: ...72 Fig E 50KCQ A04 A05 A06 Power Wiring Diagram 208 230 3 60 APPENDIX D WIRING DIAGRAMS ...
Page 73: ...73 Fig F 50KCQ A04 A05 A06 Power Wiring Diagram 460 3 60 APPENDIX D WIRING DIAGRAMS ...
Page 74: ...74 Fig G 50KCQ A04 A05 A06 Power Wiring Diagram 575 3 60 APPENDIX D WIRING DIAGRAMS ...
Page 75: ...75 Fig H 50KCQ Premier Link Control Diagram APPENDIX D WIRING DIAGRAMS ...
Page 76: ...76 Fig I 50KCQ RTU Open Control Diagram APPENDIX D WIRING DIAGRAMS ...