Trane LPC Install And Operation Instructions page 58

58
Operation
water temperature input is not valid, the
controller assumes hot water exists and
disables hydronic cooling operation.
When an entering water temperature
input is established (either hardwired or
communicated), the controller generates
an Entering Water Temp Failure diagnos-
tic, if the signal is no longer valid, and
assumes a cold entering water tempera-
ture. If the sensor or communicated value
returns to a valid input, the controller
automatically clears the diagnostic and
allows two-pipe changeover operation.
Evaporator refrigerant temperature
The universal analog input configured as
evaporator refrigerant temperature
accepts a 10Ω thermistor input. A valid
evaporator refrigerant temperature is
not required for DX cooling operation but
does aid in protecting condensing unit
compressors.
When a valid evaporator refrigerant
temperature input is available to the
controller, it is used to determine if the DX
cooling capacity should be decreased to
prevent low refrigerant temperatures.
This function is referred to as defrost
operation (see "Defrost operation"). Low
refrigerant temperatures indicate frost
conditions on the evaporator and
therefore cooling capacity must be
reduced to defrost the coil.
When the evaporator refrigerant
temperature input is established, the
controller generates an Evap Refrigerant
Temp Failure diagnostic if the signal is no
longer valid, but the diagnostic has no
affect on controller operation. If the
sensor returns to a valid input, the
controller automatically clears the
diagnostic.
general
information
Generic temperature input
The universal analog input configured as
generic temperature accepts a 10Ω
thermistor input. The input can be used in
a variety of applications using Tracer
Summit. This input has no effect on the
controller operation but will report a
Generic Temperature Failure diagnostic
message if the input becomes invalid or
out or range. The diagnostic
automatically reset when the input is
valid or in range.
J43: Duct static pressure
The duct static pressure input (terminal
J43) interfaces with a specialized
pressure transducer only. When a valid
duct static pressure value (either hard-
wired or communicated) exists and a
variable-air-volume supply fan is present,
the controller uses this value for duct
static pressure control.
When a duct static pressure is estab-
lished, the controller generates a Duct
Static Press Failure diagnostic if the
signal is no longer valid, and shuts down
the unit. When the sensor returns to a
valid input, the controller automatically
clears the diagnostic and allows the unit
to resume operation.
The Tracer AH540/541 controller, if
configured for variable-air-volume
control, cannot operate without a valid
duct static pressure input. When the
sensor returns to a valid input, the
controller resumes unit operation. The
controller is not required to have a duct
static pressure input for constant-volume
space temperature or constant-volume
discharge air temperature control.
LPC-SVX01C-EN