6. If only W3 is energized (JW1 is cut), there is no effect on
PCB. No heat is energized.
C.
Accessories
Terminals AUX+ and AUX- are energized with 24 vdc when fan
is energized. The accessory kit KFAIR0101ACR is used to
connect an EAC or humidifier.
NOTE:
Loads cannot be connected directly to AUX+ and AUX-.
Use the specified kit only.
D.
Blower
1. Blower On Delay—To optimize comfort, there is a 30-sec
blower on delay in heat pump heating mode only.
2. Blower Off Delay—Smart Heat control uses a 60-sec off
blower delay, as opposed to the standard 90-sec delay.
III.
SMART HEAT OPERATION
A.
Cooling
The Smart Heat option controls cooling mode in same manner as
conventional heat pumps are controlled. The fan has a 90-sec delay
off/on cycle down.
B.
Heat Pump Heating
The Smart Heat option does not control heating in the conventional
method. The PCB energizes compressor 30 sec before indoor fan
is energized. This allows indoor coil to heat up eliminating
cold-blow on start-up.
The electric heat is staged-on to allow continuous operation of heat
pump and electric resistance heat below balance point (below point
where heat pump cannot maintain dwelling temperature without
supplemental heat) independent of outdoor thermostats.
Although PCB has provisions for an outdoor thermostat, it is not
needed for staging. On cycle down, indoor fan remains on 60 sec
to recover heat stored in indoor coil.
C.
Defrost
The Smart Heat PCB stages the correct amount of supplemental
heat during defrost. If too much heat is added, system stays in
defrost for completion of defrost cycle even though thermostat is
satisfied. On next cycle, 1 less element is energized during next
defrost period.
NOTE:
If the signal from thermostat is interrupted (ie., thermo-
stat is satisfied) while unit is in defrost mode, the defrost cycle will
be completed before unit shuts down.
Fig. 39—Smart Heat Printed-Circuit Board (PCB)
A94127
ST1
®
®
HSCI
COMMON
DUMMY
DUMMY
240 VAC
240
VAC
JW4
JW2
JW3
JW5
JW6
JW8
JW1
R15
R27
R4
R41
1
R40
R19
R10
C9
C8
R18
R11
C7
K2
K3
LO
HI
T3
T2
T1
F1
XFORM
AUX+
AUX–
F2
FAN
R13
C10
C12
C13
FS1
R20
R9
R8
R7
R6
Z4
C5
1
MOV1
C2
C3
C6
R23
R1
R30
D5
R
C
Y
G
O
W2D
W 3
Y o
W 2T
R3
Z5
R21
JW7
R2
Z3
Z2
R16
R12
C11
R17
R5
R29
R26
R14
K1
D1
C
BE
C
BE
C
BE
D4
D2
U2
U1
LED1
D3
Q1
P1
LR40061
CLIP JUMPER FOR
HIGH SPEED FAN ONLY
Q2
1
2
3
4
5
6
7
8
9
Q3
R38
R22
R28
R25
R24
CESS430121-01A
R36
R37
C15
Z1
C14
R39
C4
CES0130025 –
SEC1
SEC2
CEPL130121-01
JW1
JW2
RECEPTACLE
LOW VOLTAGE
TERMINAL
BOARD
(CUT WHEN
OUTDOOR
THERMOSTAT
IS USED)
(HIGH FAN
ONLY WHEN
CUT)
TABLE 10—ELECTRIC HEATER STAGE LIMITING
HEATER PART NO.
STAGES (KW OPERATING)
W2T Only (JW1 cut)
W2T and W3
Heater Stage
1
2
3
4
KFAEH2201H10 or
KFCEH0101H10
10 kw Non-Fused
3
6
9
9
KFAEH2301H15 or
KFCEH0201H15
15 kw Fused
3
8
11
15
KFAEH2401H20 or
KFCEH0301H20
20 kw Fused
5
10
15
20
—47—
