Lennox XC25-024-230-01 Installation And Service Procedure page 48

Y1 DEMAND
SWITCH (S87)
CONTACTOR
DE-ENERGIZED
OPEN
ANTI-SHORT
CYCLE TIMER
ANTI-SHORT
CYCLE TIMER
CONTACTOR
SWITCH (S87)
SERVICE
2
REQUIRED
WAITING FOR
OPEN
Figure 29. Low Pressure Switch (S87) Sequence of Operation (All Versions)
XC25
LOW
PRESSURE
CLOSED
PRESSURE
OPEN
SWITCH (S87)
The thermostat terminates demand when the contactor
1.
is de-energized. If demand is satisfied when alarm is
not active, the 5-strike counter resets.
2. Lockouts can be reset by cycling power off to the out­
door control (A175) R terminal.
The low pressure switch is ignored by the system when
3.
BEGINS
the outdoor temperature is below 15°F.
INCREMENT
5-STRIKE
1
COUNTER
LED ALERT
CODE / OR
MODERATE
ALERT 410
DISPLAYED
ENDS
ENERGIZED
LOW
PRESSURE
CLOSED
PRESSURE
CLOSED
SWITCH TO
CLOSE
CONTACTOR
ENERGIZED
LOW
CLOSED
5-STRIKE
COUNTER
REACHES 5
WITHIN A SINGLE
Y1 DEMAND
LOW
PRESSURE
SWITCH (S87)
LOCKOUT
LED ALERT
CODE / OR
CRITICAL
ALERT 411
DISPLAYED
LED ALERT
CODE / OR
MODERATE
ALERT 410
DISPLAYED
48
INITIAL TRIP
SWITCH IS
IGNORED FOR
90 SECONDS
SWITCH IS CLOSED OR OUTDOOR
AMBIENT TEMPERATURE IS 15ºF
OR BELOW
SERVICE
2
REQUIRED
NORMAL
OPERATION
3