22
be generated. This error disables tenant (unoccupied) override
by the SPT sensor and prevents use of this sensor value in the
cooling/heating mode determination and the supply air reset
calculation.
ENTERING WATER TEMPERATURE ALARM
(EWT) — If an entering water temperature sensor is installed
or the unit is configured for supply air temperature reset by the
entering water temperature input, an alarm with an ID of
"ewt_alarm" will be generated if the temperature input exceeds
115 F or falls below 35 F. The alarm output will close and the
red alarm lamp will be lit; however, this alarm does not affect
unit operation.
ENTERING WATER TEMPERATURE SENSOR FAIL-
URE (EWT) — If an entering water temperature sensor is in-
stalled or the unit is configured for supply air temperature reset
by the entering water temperature input, an alarm with an ID of
"ewt_sen_alarm" will be generated if the temperature input ex-
ceeds 200 F or falls below -45 F. The alarm output will close
and the red alarm lamp will light. The EWT output will show
0
°
F and this sensor should not be used in the cooling/heating
mode determination or the supply air reset calculation (if en-
abled). This alarm will also disable water economizer opera-
tion and head pressure control.
MIXED OR RETURN AIR TEMPERATURE ALARM
(MA_RA) — If a mixed or return air temperature sensor is in-
stalled, an alarm with an ID of "mara_alarm" will be generated
if the temperature input exceeds 120 F or falls below 35 F. The
alarm output will close and the red alarm lamp will light; how-
ever, this alarm does not affect unit operation.
MIXED OR RETURN AIR TEMPERATURE SENSOR
FAILURE (MA_RA) — If a mixed or return air temperature
sensor is installed, an alarm with an ID of "mara_sen_alarm"
will be generated if the temperature input exceeds 200 F or
falls below -45 F. The alarm output will close, the red alarm
lamp will light, and the unit will output a value of 0
°
F for this
point. This invalid input is not used the supply air reset calcula-
tion, cooling/heating mode determination, or for control of an
air economizer.
OUTDOOR AIR TEMPERATURE ALARM (OAT) — If
an outdoor air temperature sensor is installed and configured,
an alarm with an ID of "oat_alarm" will be generated if the
temperature input exceeds 120 F or falls below 35 F. The alarm
output will close and the red alarm lamp will light; however,
this alarm does not affect unit operation.
OUTDOOR AIR TEMPERATURE SENSOR FAILURE
(OAT) — If an outdoor air temperature sensor is installed and
configured, an alarm with an ID of "oat_alarm" will be gener-
ated if the temperature input exceeds 200 F or falls below
-45 F. The alarm output will close and the red alarm lamp will
light. The outside air temperature output will show 0
°
F and the
program will use a value of (Economizer Se 2 F) for
the outside-air temperature in the optional airside economizer
routine.
COMPRESSOR RUNTIME ALARM — There is a set point
to define a maximum compressor runtime in hours for each
compressor. If a non-zero value is entered, the unit will gener-
ate an alarm with an ID of "dx#_rntm" when the compressor
runtime exceeds the set point. "#" designates the compressor
number. This alarm will cause the red alarm lamp to be lit, but
since it is only a status alarm, unit operation is not affected and
this does not close the alarm output.
SUPPLY FAN RUNTIME ALARM — There is a set point
to define a maximum supply fan run time. If a non-zero value
is entered, the unit will generate an alarm with an ID of
"sf_rntm" when the runtime exceeds the set point. This alarm
will cause the red alarm lamp to be lit, but since it is only a sta-
tus alarm, unit operation is not affected and this does not close
the alarm output.
SELF-TEST ALARM — When the user starts a self-test se-
quence, an alarm with an ID of "selftest_alarm" will be gener-
ated and the red alarm lamp will light. This alarm is maintained
for 4 minutes after the last self-test sequence has run. This
alarm stops normal unit operation, but the unit returns to nor-
mal operation when the alarm is cleared. The alarm output is
closed to designate each step of multi-step self-test routines
(see the Automatic Self-Test section for details).
50XJ Wiring Diagrams —
The typical wiring diagrams
for the 50XJ units are shown in Fig. 11 and 12.
