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XP21 SERIES
Y1 DEMAND
DISCHARGE
SENSOR
(RT28)*
COMPRESSOR
CONTACTOR
ENERGIZED
HIGH
PRESSURE
SWITCH (S4)
COMPRESSOR
CONTACTOR
DE−ENERGIZED
COMPRESSOR
ANTI−SHORT
CYCLE TIMER
BEGINS
INCREMENT
5−STRIKE
COUNTER
1
LED ALERT
CODE / OR
MODERATE
ALERT 414
DISPLAYED
ANTI−SHORT
CYCLE TIMER
ENDS
COMPRESSOR
CONTACTOR
ENERGIZED
DISCHARGE
SENSOR (RT28)
IS AT OR
BELOW 225ºF
WAITING FOR
TEMPERATURE
DROP TO OR
BELOW 225ºF
5−STRIKE
COUNTER
REACHES 5
WITHIN A SINGLE
Y1 DEMAND
DISCHARGE
SENSOR (RT28)
LOCKOUT
LED ALERT
CODE / OR
CRITICAL
ALERT 415
CLEARED
SERVICE
REQUIRED
2
LED ALERT
CODE / OR
MODERATE
ALERT 414
CLEARED
NORMAL
OPERATION
CLOSED
CLOSED
OPEN
OPEN
1
If 5−strike counter has four or less strikes when Y1 demand is
terminated or satisfied, the strike counter will reset to zero. In a icomfort
Touch
®
thermostat enabled setup, the thermostat will terminate demand
when the compressor contactor is de−energized. If demand is satisfied
when alarm is not active, the 5−strike counter will reset.
2
Lockouts can be reset by either cycling power off to the heat pump
control’s (A175)
R
terminal, or placing a jumper on the field test pins
(E33) between 1 to 2 seconds.
NO
*
If temperature is at or above 279ºF.
YES
Figure 31. High Discharge Temperature Sensor (RT28) Sequence of Operation
