Lennox XP21 Series User Manual

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

Lennox XP21 Series Specifications

General

Brand	Lennox
Model	XP21 Series
Category	Heat Pump
Language	English