Lennox XP17-024-230-01 Installation And Service Procedure page 53

PRESSURE
Y1 DEMAND
SWITCH (S87)
CONTACTOR
DE-ENERGIZED
OPEN
ANTI-SHORT
CYCLE TIMER
INCREMENT
COUNTER
LED ALERT
CODE / OR
MODERATE
ALERT 410
DISPLAYED
ANTI-SHORT
CYCLE TIMER
CONTACTOR
ENERGIZED
PRESSURE
SWITCH (S87)
SERVICE
2
REQUIRED
WAITING FOR
PRESSURE
OPEN
SWITCH TO
Figure 30. Low Pressure Switch (S87) Sequence of Operation (All Versions)
XP17
LOW
CLOSED
LOW
PRESSURE
OPEN
SWITCH (S87)
1
The thermostat will terminate demand when the 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 cycling power off to the outdoor
control's (A175) R terminal.
3
BEGINS
The low pressure switch is ignored by the system when the
outdoor temperature is below 15°F.
5-STRIKE
WITHIN A SINGLE
1
ENDS
LOW
CLOSED
CLOSED
CLOSE
CONTACTOR
ENERGIZED
CLOSED
5-STRIKE
COUNTER
REACHES 5
Y1 DEMAND
LOW
PRESSURE
SWITCH (S87)
LOCKOUT
LED ALERT
CODE / OR
CRITICAL
REQUIRED
ALERT 411
DISPLAYED
LED ALERT
CODE / OR
MODERATE
ALERT 410
DISPLAYED
Page 53
INITIAL TRIP
SWITCH IS
IGNORED FOR
90 SECONDS
SWITCH IS CLOSED OR OUTDOOR
AMBIENT TEMPERATURE IS 15ºF
OR BELOW
SERVICE
2
NORMAL
OPERATION
3