Lennox HP40, Руководство по установке

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System Operation
Filter Drier
The unit is equipped with a biflow filter drier. See figure 6.
If the filter needs to be replaced, order another of the
same design.
Thermostat Operation
Some heat pump thermostats incorporate isolating con-
tacts and an emergency heat function (which includes an
amber indicating light). The thermostat is not included
with the unit and must be purchased separately.
Emergency Heat Function
Some thermostats have an emergency heat function.
This feature is applicable only to those systems that have
auxiliary electric heat staged by outdoor thermostats.
When the thermostat is placed in the emergency heat
position, the outdoor unit control circuit is isolated from
the power source, and field−provided relays bypass the
outdoor thermostats. An amber indicating light simulta-
neously comes on to remind the homeowner that the unit
is operating in the emergency heat mode.
Emergency heat is usually used during a heat pump shut-
down. However, emergency heat should also be used fol-
lowing a power outage if the power has been off for over
an hour, and the outdoor temperature is below 10
C. The
system should be left in the emergency heat mode for at
least six hours to allow the crankcase heater sufficient
time to prevent compressor from slugging.
Defrost System
The HP40 defrost system includes two components: a de-
frost thermostat and a defrost control.
Defrost Thermostat
The defrost thermostat is located on the liquid line be-
tween the check/expansion valve and the distributor.
When defrost thermostat senses 5.5°C or cooler, the ther-
mostat contacts close and send a signal to the defrost
control board to start the defrost timing. It also terminates
defrost when the liquid line warms up to 21°C.
Defrost Control
The defrost control board includes the combined func-
tions of a time/temperature defrost control, defrost relay,
diagnostic LEDs and terminal strip for field wiring con-
nections. See figure 10.
The control provides automatic switching from normal
heating operation to defrost mode and back. During com-
pressor cycle (call for defrost), the control accumulates
compressor run times at 30, 60, or 90 minute field−adjust-
able intervals. If the defrost thermostat is closed when the
selected compressor run time interval ends, the defrost
relay is energized and defrost begins.
HP40 DEFROST CONTROL BOARD
24V
TERMINAL
STRIP
HIGH PRESSURE SWITCH
SAFETY CIRCUIT
CONNECTIONS
NOTE − Remove factory−
installed jumper to add
pressure switch.
S4
CONNECTION FOR
OPTIONAL
HIGH PRESSURE
SWITCH
DEFROST
INTERVAL
TIMING PINS
High
Pressure
Switch
DIAGNOSTIC
LEDs
FIGURE 10