Honeywell Home THX9321 Prestige 2.0 Manual page 96

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THX9321 PRESTIGE 2.0 AND THX9421 PRESTIGE
needed to keep the indoor temperature within 1 °F (0.5 °C)
degree of the setpoint. The thermostat turns on stage 2
when the capacity on stage 1 reaches 90%.
Cool Differential
The indoor temperature must rise to the selected
differential setting before the thermostat turns on the
stage of cooling. For example, if stage 2 is set to 2 °F (1.0
°C), the indoor temperature must be 2 °F (1.0 °C) away
from the setpoint before stage 2 turns on. When set to
Comfort, the thermostat uses the stage cooling as needed
to keep the indoor temperature within 1 °F (0.5 °C) degree
of the setpoint. The thermostat turns on stage 2 (or the
next stage) when the capacity on stage 1 reaches 90%.
TO CHANGE DIFFERENTIAL SETTINGS
1. Select Advanced Options to view/adjust differentials
between all stages.
Fig. 194.
2. Default is Comfort. Adjust differentials as needed.
Fig. 195.
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
68-0311—08
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IAQ WITH EIM
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 maintain
the setpoint, the thermostat may turn on the
backup heat earlier when the user raises the set-
point. This does NOT apply to heat pumps with
fossil fuel backup heat.
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