Delta T Alerts - Honeywell Home THX9321 Prestige 2.0 Manual

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THX9321 PRESTIGE 2.0 AND THX9421 PRESTIGE
Advanced Options for Delta T Diagnostics
To set Advanced Options for Delta T Diagnostics, select Yes
for ISU 13015.Then the following advanced options are
displayed:
• Delta T Alert Sensitivity (ISU 13180; Default: 3)
• Display Delta T Alerts to User (ISU 13190; Default: Yes)
• Allow Delta T Diagnostics:
— during humidification (ISU 13020; Default: Yes)
— during dehumidification (ISU 13030; Default: Yes*)
— during ventilation (ISU 13040; Default: Yes)
— only when indoor temperature is within a certain
range (ISUs 13050, 13090, 13130; Default: Always)
— only when indoor humidity is within a certain range
(ISUs 13060,13100, 13140; Default: Always)
— only when outdoor temperature is within a certain
range (ISUs 13070, 13110, 13150; Default: Always)
— only when outdoor humidity is within a certain range
(ISUs 13080, 13120, 13160; Default: Always)
* Default is Yes for Dehumidifiers and A/C with High Speed
Fan. The thermostat does NOT allow Delta T diagnostics
during dehumidification if it is setup for A/C with Low
Speed Fan, Hot Gas Bypass, or Reheat.
The Delta T Alert Sensitivity is set on a scale of 1–5 in ISU
13180 (1 is the least sensitive; 5 is the most sensitive):
Table 7. Delta T Alert Sensitivity (ISU 13180).
Setting Alert is logged and user is alerted if
1 10 of the last 15 valid cycles have the same fault, or
25 of the last 30 valid cycles have the same fault.
2 10 of the last 15 valid cycles have the same fault, or
20 of the last 30 valid cycles have the same fault.
3 5 of the last 5 valid cycles have the same fault, or
(Default) 10 of the last 15 valid cycles have the same fault, or
15 of the last 30 valid cycles have the same fault.
4 5 of the last 5 valid cycles have the same fault, or
8 of the last 15 valid cycles have the same fault, or
15 of the last 30 valid cycles have the same fault.
5 3 of the last 5 valid cycles have the same fault, or
8 of the last 15 valid cycles have the same fault, or
10 of the last 30 valid cycles have the same fault.
By default, Delta T alerts are displayed to the user, but can
be turned off and on in ISU 13190.

Delta T Alerts

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.
This 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.
68-0311—08
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IAQ WITH EIM
There are three alerts each for the heating and cooling
system. They occur when:
• the system is not operating
NOTE: The thermostat displays an alert when the
• the system is operating below the minimum Delta T limit
• the system is operating above the maximum Delta T
limit
Delta T Alerts are displayed for basic failures including no
heating or no cooling that may be related to bad igniter,
bad flame sensor, bad gas valve, bad draft motor, bad
blower, bad contactor, bad startup capacitor, dead
compressor, etc.
Delta T Alerts are also displayed for performance related
issues such as dirty air filter, blocked registers, loss of
refrigerant, dirty a-coil, frozen a-coil, cracked heat
exchanger, dirty burners, burners need adjustment, etc.
Alerts are displayed to the user on the home screen. See
Fig. 161 for an example.
When the user presses the alert for more information, the
Notification screen is displayed, prompting them to
perform some basic troubleshooting and, if the problem
persists, contact their dealer. See Fig. 162 as an example.
Alerts are also recorded in the Alerts Log. See "Data Logs"
beginning on page 89.
88
system does not reach a Delta T of 5 F after
the thermostat calls for a reasonable period
of time.
Fig. 161.
Fig. 162.