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®
THX9321 PRESTIGE
2.0 AND THX9421 PRESTIGE
UNIVERSAL INPUTS
(S1, S2, S3, S4)
S1, S2, S3, and S4 are universal inputs that can be setup to
work with a sensor or dry contact device in the Installer
Setup. Setup options and compatible sensors are listed
below. See wiring diagrams on page 95 and page 158.
Universal Input Options
Indoor Air Sensor (ISU 5000)
• C7189U1005 (10K)
• C7772A1004 (20K)
• C7772A1012 (20K)
• TR21 (20K)
• TR21-A (10K)
Outdoor Air Sensor (ISU 5000)
• C7089U1006 (10K)
Discharge/Return Air Sensors (ISU 5000)
• C7735A1000 (10k)
• C7770A1006 (20K)
• C7041 (20K)
Occupancy Sensor for Remote Setback (ISU 6000)
• WSK-24
Dry Contact Alerts (ISU 6000)
• Low Voltage Dry Contact Device
NOTE: S1, S2, S3, and S4 terminals are only available on
the Equipment Interface Module (EIM).
ALERTS AND DIAGNOSTICS
The thermostat uses alerts and diagnostics to provide
greater comfort and efficiency. Alerts and diagnostics can
notify customers when maintenance or service is needed,
and display your contact information to make it easy for
them to reach you.
Delta T Diagnostics
If discharge and return air sensors are installed, the
thermostat can track system performance over time. It
measures this as "Delta T." The thermostat monitors Delta
T and displays an alert on the home screen when the
system exceeds the limits you set.
Delta T Diagnostics tells you if the system is performing
above or below expected standards which would normally
go unnoticed, and may cause unnecessary energy use. It
can also detect and warn about problems early, before
heating or cooling equipment fails.
The thermostat will measure and record Delta T of the
system for each stage you test. This information can be
used to set the proper Delta T fault limits of the system.
When the system operates outside those limits multiple
times (see "Advanced Options for Delta T Diagnostics"
68-0311—07
®
IAQ WITH EIM
beginning on page 89), an alert is recorded in the log. If
configured to do so, the system will then display an alert to
the homeowner, along with your contact information.
Before You Set Up Delta T
Diagnostics
Refer to the information below for tips on installation and
setup of Delta T Diagnostics.
1. Refer to Fig. 10–14 for the placement of the
Discharge and Return Air Sensors.
2. In gas or oil forced air systems, Delta T will continue
to rise for several minutes even after Delta T begins
to stabilize. Be sure the Maximum Delta T Limit is set
higher than the expected stable Delta T. See Fig. 148.
RUN TIME WHEN THERMOSTAT
COMPARES DELTA T TO THE
MINIMUM AND MAXIMUM DELTA T LIMITS
3. Delta T can be affected by indoor and outdoor
conditions for heat pumps and cooling systems.
Consider the total range of normal performance
when setting the Delta T Limits.
For example, in cooling, you might have a Delta T of
20 °F when the outdoor humidity is 50% and a
Delta T of 16 °F when the outdoor humidity is 85%.
You can either set Limits further apart and monitor
Delta T during all indoor and outdoor conditions or
set Limits closer together and turn off diagnostics
during certain indoor and outdoor conditions (see
"Advanced Options for Delta T Diagnostics"
beginning on page 89).
For example, you can set limits closer together and
then turn off diagnostics when outdoor temperature
is above 90 degrees and outdoor humidity is above
85%.
4. Verify the filter is clean and all the registers are open
before running an equipment test.
5. Select a Run Time when Delta T begins to stabilize
during the equipment test.
86
MAXIMUM DELTA T LIMIT
MINIMIUM DELTA T LIMIT
DELTA T BEGINS TO STABILIZE
DELTA T NOT STABLE
RUN TIME
Fig. 148.
DELTA T STABLE
M31489
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