Delay Mode - Lennox Elite Series Installation Instructions Manual

EAR _LY- -
ON
I
= ON LATER MODELS
MODELS
= DISCHARGE LINE SENSOR
I
LOCATIONS
L ..... ,
DEFROST BOARD
DEFROST SENSOR
HARNESS
SENSOR
COIL SENSOR -
APPLY GREASE BETWEEN
RETURN BEND AND SENSOR
COIL SENSOR - 12
TUBES UP FROM
BOTTOM (11-1/2")
XP16-048
COIL SENSOR -
13 TUBES UP FROM
BOTTOM (12-1/2")
Figure 39. Sensor Locations
The discharge line sensor, which covers a range of 150°F
(65°C) to 350°F (176°C), is designed to mount on a V2"
refrigerant discharge line.
NOTE - Within a single room thermostat demand, if
5-strikes occur, the board will lockout the uniL Defrost
board 24 volt power R must be cycled OFF or the TEST
pins on board must be shorted between I to 2 seconds to
reset the board.
Second-Stage Operation--If the board receives a call for
second-stage compressor operation Y2 in heating or
cooling mode and the first-stage compressor output is
active, the second-stage compressor solenoid output will
be energized.
If first-stage compressor output is active in heating mode
and the outdoor ambient temperature is below the selected
compressor lock-in temperature, the second-stage
compressor solenoid output will be energized without the
Y2 input. If the jumper is not connected to one of the
temperature selection pins on P3 (40, 45, 50, 55°F), the
default Iockqn temperature of 40°F (4.5°C) will be used.
The board de-energizes the second-stage compressor
solenoid output immediately when the Y2 signal is
removed or the outdoor ambient temperature is 5°F above
the selected compressor lock-in temperature, or the
first-stage compressor output is de-energized for any
reason.
Defrost Temperature Termination Shunt (Jumper)
Pins--The defrost board selections are: 50, 70, 90, and
100°F (10, 21, 32 and 38°C). The shunt termination pin is
factory set at 50°F (10°C). If temperature shunt is not
installed, default termination temperature is 90°F (32°C).
DELAY MODE
The defrost board has a field-selectable function to reduce
occasional sounds that may occur while the unit is cycling
in and out of the defrost mode. When a jumper is installed
on the DELAY pins, the compressor will be cycled off for 30
seconds going in and out of the defrost mode. Units are
shipped with jumper installed on DELAY pins.
NOTE - The 30 second off cycle is NOTfunctional when
jumpering the TEST pins.
OPERATIONAL DESCRIPTION
The defrost control board has three basic operational
modes: normal, defrost, and calibration.
• Normal Mode--The demand defrost board monitors
the O line, to determine the system operating mode
(heat/cool), outdoor ambient temperature, coil
temperature (outdoor coil) and compressor run time to
determine when a defrost cycle is required.
• Calibration Mode--The board is considered
uncalibrated when power is applied to the board, after
cool mode operation, or if the coil temperature
exceeds the termination temperature when it is in heat
mode.
Calibration of the board occurs after a defrost cycle to
ensure that there is no ice on the coil. During
calibration, the temperature of both the coil and the
ambient sensor are measured to establish the
temperature differential which is required to allow a
defrost cycle.
• Defrost Mode--The following paragraphs provide a
detailed description of the defrost system operation.
Page 23
XP16 SERIES