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Table 10. CBX25UHV, Thermostat and Two‐Stage Outdoor Unit Operating Sequence
Operating Sequence
System Demand
System Response
System
Condition
Step
Thermostat Demand
Relative Humidity
Com
pressor
Air
Handler
CFM
(COOL)
Comments
Y1
Y2
O
G
W1
W2
Status
D
NO CALL FOR DEHUMIDIFICATION
Normal Operation -
Y1
1
On
On
On
Acceptable
24 VAC
Low
70%
Compressor and indoor
air handler follow thermo
stat demand.
Normal Operation -
Y2
2
On
On
On
On
Acceptable
24 VAC
High
100%
Room Thermostat Calls for First-Stage Cooling
BASIC MODE (only active on a Y1 thermostat demand)
Normal Operation
1
On
On
On
Acceptable
24 VAC
Low
70%
Thermostat energizes Y2
and de-energizes D on a
call for dehumidification.
Dehumidification
Call
2
On
On
On
On
Demand
24 VAC
High
60%/65%
70%*
PRECISION MODE (operates independent of a Y1 thermostat demand)
Normal Operation
1
On
On
On
Acceptable
24 VAC
Low
70%
Dehumidification mode
begins when humidity is
greater than set point.
Dehumidification
call
2
On
On
On
On
Demand
0 VAC
High
60%/65%
70%*
Dehumidification
call ONLY
1
On
On
On
On
Demand
0 VAC
High
60%/65%
70%*
Thermostat will try to
maintain room humidity
setpoint by allowing the
room space to maintain a
cooler room thermostat
setpoint.**
Room Thermostat Calls for First- and Second-Stage Cooling
BASIC MODE (only active on a Y1 thermostat demand)
Normal Operation
1
On
On
On
On
Acceptable
24 VAC
High
100%
Thermostat energizes Y2
and de-energizes D on a
call for dehumidification
Dehumidification
Call
2
On
On
On
On
Demand
0 VAC
High
60%/65%
70%*
PRECISION MODE (operates independent of a Y1 thermostat demand)
Normal Operation
1
On
On
On
On
Acceptable
24 VAC
High
100%
Dehumidification mode
begins when humidity is
greater than set point
Dehumidification
call
2
On
On
On
On
Demand
0 VAC
High
60%/65%
70%*
Dehumidification
call ONLY
1
On
On
On
On
Demand
0 VAC
High
60%/65%
70%*
Thermostat will try to
maintain room humidity
setpoint by allowing the
room space to maintain a
cooler room thermostat
setpoint**
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.
