Heat Pump And Backup Heat Operation; Geothermal Radiant Heat - Honeywell TH8321 Product Data

HEAT PUMP AND BACKUP HEAT OPERATION

Heat pump with outdoor temperature lockouts
Outdoor temperature lockouts are optional. See Installer Setup options (ISU 312).
Alert Light - General
An alert light is located in the lower right corner of the
thermostat. See Fig. 28 and 29. This light turns red when
an alert is active or the system is set to the Em. Heat mode.
Alert Light - Heat Pump Systems
When the L terminal is wired to a compressor monitor and
it receives 24 volts, the alert light on the thermostat will
turn red to indicate a system problem. The thermostat
monitors 24 volts on the L terminal in Heat, Cool and Auto
modes.
Alert Light - Emergency Heat Indication
When the thermostat is setup for a Heat Pump with an
Auxiliary Heat source, the alert light will turn red when the
user sets the system to the Em. Heat mode. It is normal for
the alert light to turn red in the Em. Heat mode to remind
the user that they are currently operating their Emergency
Heat and the Heat Pump is locked out.

Geothermal Radiant Heat

The thermostat can be setup to control Geothermal
Radiant Heat, Geothermal Forced Air Heat and Backup
Heat, all from one thermostat. The thermostat stages the
equipment starting with the Geothermal Radiant Heat
followed by Geothermal Forced Air Heat and then Backup
VISIONPRO® 8000 SMART THERMOSTAT
Heat as needed to maintain the desired temperature. The
thermostat allows you to set differential temperature
settings between each stage if you want the equipment to
stage a certain way (see ISU 303 to ISU 309, page 16). For
additional wiring diagrams, see "Wiring" beginning on
page 84.
NOTE: To turn off Radiant Heat during the shoulder sea-
sons, install an outdoor reset control and connect
to the Radiant Heat or switch the thermostat to
Emergency Heat mode.
Electric Backup Heat (Backup Heat
Allowed to Run with Heat Pump)
HEAT MODE
The thermostat turns on Backup Heat only when the indoor
temperature drops to the selected Backup Heat Droop
setting or the Backup Heat Upstage Timer expires
(whichever occurs first). Geothermal Radiant Heat and
Geothermal Forced Air Heat stay on when the Backup Heat
turns on.
EMERGENCY HEAT MODE
The thermostat turns on the Backup Heat to maintain the
desired temperature setting. Geothermal Radiant Heat and
Geothermal Forced Air Heat are not used.
55 33-00096—04