Honeywell Home THX9321 Prestige 2.0 Manual page 87

Run a Test for Each Stage
Follow these steps to run a test for each stage in the HVAC
system.
1. Turn on stage 1.
Fig. 157.
2. For each stage you test, wait until Delta T begins to
stabilize, then turn on the next stage (if present). See
Fig. 158 for an example.
Fig. 158.
3. Press Next Step after Delta T stabilizes for the last
stage. The thermostat saves the Delta T and Run
Time Data for each stage you test and is displayed on
the next screen.
NOTE: The thermostat only saves test data for stages that
run 1 minute or longer.
®
THX9321 PRESTIGE 2.0 AND THX9421 PRESTIGE
Set Delta T Limits
1. Press Stage 1 to set the limits and run time (see
Fig. 159). Use the saved test data located in the upper
right corner of the screen to set the Delta T Minimum
and Maximum Limits and the Run Time (see
Fig. 160).
2. Press the up or down arrows to set the Minimum and
Maximum Limits and the Run Time.
3. Set appropriate Minimum and Maximum Delta T
Limits based on the reading from the equipment test
and what you consider to be unacceptable perfor-
mance from the heating and cooling equipment.
4. When setting the run time, select a setting based on
when Delta T began to stabilize during the equipment
test. In the example shown in Fig. 158 and 160, Delta
T began to stabilize around 10-11 minutes.
5. Set the limits and run time for all stages of cooling
using steps 1–4 above.
6. Repeat steps 1–5 above for Heating.
After Delta T Diagnostics Setup is
Complete
The thermostat will measure Delta T after the specified run
time, and compare Delta T to the minimum and maximum
limits for each valid cycle. If the system operates below the
minimum limit or above the maximum limit multiple times
(see Table 7), an alert is recorded in the Alerts Log. If
configured to do so, an alert is displayed to the user
(Display Delta T Alerts to User, ISU 13190). The user is
alerted by default. For example, if 10 of the last 15 cycles
have the same fault, an alert is logged and the user is
alerted.
87
®
IAQ WITH EIM
Fig. 159.
Fig. 160.
68-0311—08