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XP21
Y1 DEMAND
HIGH
PRESSURE
SWITCH (S4)
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 412
DISPLAYED
ANTI−SHORT
CYCLE TIMER
ENDS
COMPRESSOR
CONTACTOR
ENERGIZED
HIGH
PRESSURE
SWITCH (S4)
WAITING FOR
PRESSURE
SWITCH TO
CLOSE
5−STRIKE
COUNTER
REACHES 5
WITHIN A SINGLE
Y1 DEMAND
HIGH
PRESSURE
SWITCH (S4)
LOCKOUT
LED ALERT
CODE / OR
CRITICAL
ALERT 413
CLEARED
SERVICE
REQUIRED
2
LED ALERT
CODE / OR
MODERATE
ALERT 412
DISPLAYED
SERVICE
REQUIRED
2
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
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.
OPEN
CLOSED
CLOSED
Figure 44. High Pressure Switch (S4) Sequence of Operation (All Versions)