58
Fig. 18 — SAT and OAT Thermistor Mounting
REFRIGERANT TEMPERATURES
Condenser coil temperatures are measured with 5 kilo-ohm
thermistors. These measurements provide an approximate satu-
rated condensing temperature for each circuit (
SCT.A
,
SCT.B
).
Figures 19-23 show the factory locations for the SCT thermis-
tors. Ensure that thermistors are placed at the correct location
and are snapped securely over the return bend so that contact is
made between the thermistor and the tube.
THERMISTOR/TEMPERATURE SENSOR CHECK
A high quality digital volt-ohmmeter is required to perform
this check.
Connect the digital voltmeter across the appropriate thermistor
terminals at the J8 terminal strip on the Main Base Board (see
Major System Components on p. 68).
Using the voltage reading obtained, read the sensor tempera-
ture from Tables 22 and 23.
To check thermistor accuracy, measure temperature at probe
location with an accurate thermocouple-type temperature-mea-
suring instrument. Insulate thermocouple to avoid ambient
temperatures from influencing reading. Temperature measured
by thermocouple and temperature determined from thermistor
voltage reading should be close, within 5°F if care was taken in
applying thermocouple and taking readings.
If a more accurate check is required, unit must be shut down
and thermistor removed and checked at a known temperature
(freezing point or boiling point of water) using either voltage
drop measured across thermistor at the J8 terminal, or by deter-
mining the resistance with unit shut down and thermistor dis-
connected from J8. Compare the values determined with the
value read by the control in the Temperatures mode using the
scrolling marquee display.
SENSOR TRIM
Corrective offsets can be applied to the space temperature and
the supply air temperature sensor readings. These corrections
are set in the
Configuration
TRIM
menu for the display, or
in the
Maintenance
TRIM
table for CCN. See the Indoor Air
Quality section for available adjustments to IAQ and OAQ
sensor readings. The space temperature may be corrected by
entering either a calibration temperature value in
SPT.C
, or an
offset temperature value in
SPT.T
. The supply-air temperature
may be corrected by entering either a calibration temperature
value in
SAT.C
, or an offset temperature value in
SAT.T
. If in-
stalled, the return air temperature may be corrected by entering
either a calibration temperature value in
RAT.C
, or an offset
temperature value in
RAT.T
. Temperature corrections should
only be made if sensor readings are compared to an accurate
reference temperature measurement device.
Summary of Contents for /50HC 04-28
Page 69: ...69 Fig 24 Typical Control Diagram for 48HC 04 14 Units 48HC 08 09 shown ...
Page 70: ...70 Fig 25 Typical Power Diagram for 48HC 04 14 Units 48HC 08 09 shown ...
Page 71: ...71 Fig 26 Typical Control Diagram for 50HC 04 14 Units 50HC 14 shown ...
Page 72: ...72 Fig 27 Typical Power Diagram for 50HC 04 14 Units 50HC 14 Non Humidi MiZer shown ...
Page 73: ...73 Fig 28 Typical Control Diagram 48HC 17 28 Units ...
Page 74: ...74 Fig 29 Typical Control Diagram 50HC 17 28 Units ...
Page 75: ...75 Fig 30 Typical Humid MiZer Power Diagram and Component Arrangement 48 50HC 17 28 Units ...
Page 76: ...76 Fig 31 Typical Non Humid MiZer Power Diagram and Component Arrangement 48 50HC 17 28 Units ...
Page 89: ...89 Fig 42 Modulating ERV Wiring Schematic ...
Page 90: ...90 Fig 43 EnergyX ERV Control Box Component Layouts ...
Page 101: ...101 Fig 59 Exhaust Fan Assembly Removal Exhaust Fan Assembly ...
Page 141: ......