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THX9321 PRESTIGE
®
2.0 AND THX9421 PRESTIGE
®
IAQ 2.0 WITH EIM
68-0311—01 60
TO CHANGE DIFFERENTIAL SETTINGS
1. Select Advanced Options to view/adjust differentials
between all stages.
Fig. 90.
2. Default is Comfort. Adjust differentials as needed.
Fig. 91.
Backup Heat Differential (Droop)
A Backup Heat Differential is available for any system with 2
heating types. For example:
• Heat Pumps with any type of Backup Heat
• Radiant Heat with any type of Backup Heat
• Hot Water Fan Coil with any type of Backup Heat
The Backup Heat Differential restricts backup heat during the
following conditions:
• Normal Operation
• Manual Setpoint Changes
The options are:
• Comfort – keeps temperature within 1 degree of the
setpoint.
• 2 to 15 °F – Backup heat is not used unless the indoor
temperature drops to the selected Backup Heat Differential.
For example, if the Backup Heat differential is set to 2 °F
(1.0 °C), the indoor temperature must be 2 °F (1.0 °C) away
from the setpoint before the backup heat turns on.
NORMAL OPERATION
When the Backup Heat Differential is set to Comfort, the
thermostat uses backup heat as needed to keep the indoor
temperature within 1 °F (0.5 °C) of the setpoint.
When the Backup Heat Differential is set to 2 °F or higher,
backup heat is not used unless the indoor temperature drops
to the Backup Heat Differential setting or the Backup Heat
Upstage Timer expires, whichever occurs first. The upstage
timer starts when the highest stage of the previous equipment
type turns on.
MANUAL TEMPERATURE CHANGE
When the Backup Heat Differential is set to Comfort, the
thermostat uses backup heat as needed to keep the indoor
temperature within 1 °F (0.5 °C) of the setpoint.
When the Backup Heat Differential is set to 2 °F or higher, if the
primary heat is making progress as expected, backup heat will
not be used to reach the new setpoint. Set to a higher number
to use less backup heat (a greater difference between the
current indoor temperature and the new setpoint is required to
turn on backup heat). See notes below.
PROGRAMMED RECOVERY
If the primary heat is making progress as expected, backup
heat will not be used to reach the setpoint of the next program
period. Backup heat is always restricted during a programmed
recovery when the Adaptive Intelligent Recovery feature is
used. See note below.
NOTE: During a programmed recovery (or when the tem-
perature setpoint is changed by the user), the
thermostat waits to turn on the backup heat
depending on system performance, load condi-
tions and how many degrees the temperature set-
point is changed. Backup heat will be used ONLY
when the temperature is not rising quickly
enough to reach the setpoint in a reasonable time.
NOTE: If the backup heat was used in the last 2 hours
because the primary heat was not able to main-
tain the setpoint, the thermostat may turn on the
backup heat earlier when the user raises the set-
point.
TO CHANGE BACKUP HEAT DIFFERENTIAL (DROOP)
SETTINGS
1. Select Advanced Options or Basic Options to view/adjust
Backup Heat Differential settings.
Fig. 92.
2. Default is Comfort. Adjust differentials as needed.