Universal Inputs; Universal Input Options; Before You Set Up Delta T Diagnostics; Alerts And Diagnostics - Honeywell THX9321 Prestige 2.0 Product Data

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 96 and page 154.

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" beginning on page 90), 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.
®
THX9321 PRESTIGE 2.0 AND THX9421 PRESTIGE
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. 147.
DELTA T NOT STABLE
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 90).
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.
6. Set Minimum and Maximum Delta T Limits based on
what you consider to be unacceptable performance from
the heating and cooling equipment.
NOTE: When the system operates below the Minimum
Limit or above the Maximum Limit multiple
times (Table 7), an alert is recorded in the log. If
configured to do so, the thermostat will display
an alert to the user, along with your contact
information.
87
®
IAQ WITH EIM
MAXIMUM DELTA T LIMIT
MINIMIUM DELTA T LIMIT
DELTA T BEGINS TO STABILIZE
DELTA T STABLE
RUN TIME
Fig. 147.
M31489
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