Honeywell Prestige THX9321 System Installation Manual page 20

System Installation Guide
Basic and Advanced Temperature Control Options {iSU 3010)
Basic Options: The Installer Setup displays basic temperature control options
which include Backup Heat Differential, Backup Heat Upstage Timer and Outdoor
Temperature Lockouts. Note: Outdoor Temperature Lockouts only apply to Heat
Pump applications.
Advanced Options: The Installer Setup displays both Basic and Advanced
Options. Advanced temperature control options include Finish With High Coot
Stage, Finish With High Heat Stage, Temperature Differential settings per stage
and Cycle Rate settings per stage.
FinishWith High Heat or C001 Stage- Whena multi-stage heatingor coolingsystem is used,this featurekeeps the high stage
of the heatingor cooling equipmentrunning until the desired setpointis reached. Recommendedsettingfor Geothermal Heat
Pumpsto allowthe 100p to rest.
Backup heat differential and upstage timer
A backup heat differential and backup heat upstage timer can be set on any
system that has more than one type of heating equipment. See installer setup
options (ISU 3070-3110).
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 o F (0.5 ° C) of the set-
point. If the Backup Heat Upstage Timer is used, the thermostat delays the back-
up heat from turning on until the timer expires.
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. 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 o F (0.5 ° C) of the set-
point.
When the Backup Heat Differential is set to 2 ° F or higher, if the primary heat is
making progress as expected, backup heat witl 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 note 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 atway_ restrict=
ed during a programmed recovery when the Adaptive Intelligent Recovery feature
is used. Set the Backup Heat Differential to a higher number to use less backup
heat. See note below.
During a programmedrecovery(or when the temperature setpointis changedby the user), the thermostat waitsto turn on the
backup heat dependingon system performance,load conditionsand how manydegreesthe temperaturesetpoint is changed.
Backup heatwill be used ONLYwhen the temperature is not rising quickly enough to reach the setpoint in a reasonabletime.
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