Lennox XP21 Series Installation Instructions Manual page 37

PRESSURE
Y1 DEMAND
SWITCH (S87)
COMPRESSOR
CONTACTOR
DE−ENERGIZED
OPEN
COMPRESSOR
ANTI−SHORT
CYCLE TIMER
BEGINS
INCREMENT
5−STRIKE
COUNTER
LED ALERT
CODE / OR
MODERATE
ALERT 410
DISPLAYED
ANTI−SHORT
CYCLE TIMER
ENDS
COMPRESSOR
CONTACTOR
ENERGIZED
PRESSURE
SWITCH (S87)
SERVICE
2
REQUIRED
WAITING FOR
PRESSURE
OPEN
SWITCH TO
CLOSE
LOW
CLOSED
LOW
PRESSURE
OPEN
SWITCH (S87)
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.
WITHIN A SINGLE
1
LOW
CLOSED
CLOSED
Figure 29. Low Pressure Switch (S87) Sequence of Operation
COMPRESSOR
CONTACTOR
ENERGIZED
CLOSED
5−STRIKE
COUNTER
REACHES 5
Y1 DEMAND
LOW
PRESSURE
SWITCH (S87)
LOCKOUT
LED ALERT
CODE / OR
CRITICAL
ALERT 411
DISPLAYED
LED ALERT
CODE / OR
MODERATE
ALERT 410
DISPLAYED
Page 37
INITIAL TRIP
SWITCH IS
IGNORED FOR
90 SECONDS
SWITCH IS CLOSED OR OUTDOOR
AMBIENT TEMPERATURE IS 15ºF
OR BELOW
SERVICE
2
REQUIRED
NORMAL
OPERATION
XP21 SERIES