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TABLE 4. CBA25UHV Thermostat and Two-Stage Outdoor Unit Operating Sequence
Operating Sequence
System
Step
Y1
Condition
NO CALL FOR DEHUMIDIFICATION
Normal Operation
1
On
- Y1
Normal Operation
2
On
- Y2
BASIC MODE (only active on a Y1 thermostat demand)
Normal Operation
1
On
Dehumidification
2
On
Call
PRECISION MODE (operates independent of a Y1 thermostat demand)
Normal Operation
1
On
Dehumidification
2
On
Call
Dehumidification
1
On
Call ONLY
BASIC MODE (only active on a Y1 thermostat demand)
Normal Operation
1
On
Dehumidification
2
On
Call
PRECISION MODE (operates independent of a Y1 thermostat demand)
Normal Operation
1
On
Dehumidification
2
On
Call
Dehumidification
1
On
Call ONLY
Jumpers at indoor unit with a two-stage outdoor unit
With Condensing unit - Y2 and R to O
With Heat Pump - none
* During dehumidification, cooling air handler speed is as follows: 70% of COOL cfm for 018, 024, 030; 65% for 036; 60% for 042, 048 and 060 units.
** Thermostat will maintain the room temperature up to 2°F (1.2°C) cooler than the room thermostat setting in precision mode.
HEAT JUMPER
The HEAT jumper is used to determine CFM during elec-
tric heat operation only. These jumper selections are acti-
vated only when W1 is energized.
DELAY JUMPER
The DELAY jumper is used to set the specific motor fan
operation during cooling mode. Depending on the appli-
cation, one of four options may be chosen by moving the
jumper to the appropriate set of pins.
#1 Pins Jumpered
A- Motor runs at 100% until demand is satisfied.
B- Once demand is met, motor ramps down to stop.
A
100% CFM
OFF
COOLING
#2 Pins Jumpered
A- Motor runs at 100% until demand is satisfied.
B- Once demand is met, motor runs at 100% for 60 sec-
onds.
System Demand
Thermostat Demand
Y2
O
G
W1
W2
On
On
On
On
On
Room Thermostat Calls for First-Stage Cooling
On
On
On
On
On
On
On
On
On
On
On
On
On
Room Thermostat Calls for First- and Second-Stage Cooling
On
On
On
On
On
On
On
On
On
On
On
On
On
On
On
B
OFF
DEMAND
Relative Humidity
Status
D
pressor
Acceptable
24 VAC
Low
Acceptable
24 VAC
High
Acceptable
24 VAC
Low
Demand
24 VAC
High
Acceptable
24 VAC
Low
Demand
0 VAC
High
Demand
0 VAC
High
Acceptable
24 VAC
High
Demand
0 VAC
High
Acceptable
24 VAC
High
Demand
0 VAC
High
Demand
0 VAC
High
C- Motor ramps down to stop.
A
OFF
#3 Pins Jumpered
A- Motor runs at 82% for approximately 7-1/2 minutes. If
demand has not been satisfied after 7-1/2 minutes.
B- Motor runs at 100% until demand is satisfied.
C- Once demand is met, motor ramps down to stop.
A
OFF
#4 Pins Jumpered
A- Motor runs at 50% for 30 seconds.
B- Motor then runs at 82% for approximately 7-1/2 min-
utes. If demand has not been satisfied after 7-1/2 minutes,
C- Motor runs at 100% until demand is satisfied.
Page 9
System Response
Air
Handler
CFM
(COOL)
Comments
70%
Compressor and indoor air handler follow
thermostat demand
100%
70%
60%/65%
gizes D on a call for dehumidification
70%*
70%
60%/65%
midity is greater than set point
70%*
midity setpoint by allowing the room
60%/65%
70%*
stat setpoint**
100%
60%/65%
gizes D on a call for dehumidification
70%*
100%
60%/65%
midity is greater than set point
70%*
60%/65%
70%*
midity setpoint by allowing the room
stat setpoint**
B
100% CFM
100% CFM
(60 seconds)
COOLING DEMAND
B
7 1/2 MIN
100% CFM
82%CFM
COOLING DEMAND
C
OFF
C
OFF
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