Inputs (S1, S2, S3, S4); Alerts And Diagnostics; Delta T Diagnostics; Before You Set Up Delta T Diagnostics - Honeywell Home THX9321 Prestige 2.0 Manual

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THX9321 PRESTIGE 2.0 AND THX9421 PRESTIGE
Output Options
THX9421 with Equipment Interface Module (U1, U2, U3):
• Humidification (ISU 8030)
• Dehumidification (ISU 9040)
• Ventilation (ISU 10020)
• Cool Stage 3 (ISU 2080)
• Cool Stage 4 (ISU 2090)
• Geothermal Radiant Heat (ISU 2030, 2040)
THX9321 Thermostat Only (U1, U2)
• Humidification (ISU 8030)
• Dehumidification (ISU 9040)
• Ventilation (ISU 10020)
• Cool Stage 3 (ISU 2080)
• Cool Stage 4 (ISU 2090)
• Conventional Heat Stage 3 (ISU 2100, 2140)
• Backup Heat Stage 2 for Heat Pumps (ISU 2170)
• Geothermal Radiant Heat (ISU 2030, 2040)

INPUTS (S1, S2, S3, S4)

S1, S2, S3, and S4 are 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 94 and page 154.
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.
68-0311—08
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IAQ WITH EIM

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 88), 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
84
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