Geothermal Radiant Heat - Honeywell Home THX9321 Prestige 2.0 Manual

Backup Heat Type
Electric forced air
Gas or oil forced air
Hot water radiant heat
Hot water fan coil
Other

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
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 3030 to ISU 3090, page 31).
For additional wiring diagrams, see page 140.
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 Differential
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.
Fossil Fuel Backup Heat (Backup Heat
NOT 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 Differential
setting or the Backup Heat Upstage Timer expires
(whichever occurs first). Geothermal Forced Air Heat turns
off when the Backup Heat turns on. Geothermal Radiant
Heat stays on when the Backup Heat turns on.
EM. 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.
THX9321 PRESTIGE
Table 8. Heat Pump and Backup Heat Operation.
Backup Heat Operation
Allowed to run with heat pump
NOT allowed to run with heat pump
Allowed to run with heat pump
Selectable in installer setup
Selectable in installer setup
®
2.0 AND THX9421 PRESTIGE
Backup Heat Fan Operation
Thermostat controls fan
Equipment controls fan
[n/a]
Thermostat controls fan
Selectable in installer setup
Set Up Geothermal Radiant Heat
1. Select Geothermal Radiant Heat as shown in
Fig. 202.
2. Select the number of Radiant Heat Stages. See
Fig. 203.
3. Select the U terminals wired to the Geothermal Radi-
ant Heat. See Fig. 204.
99
®
IAQ WITH EIM
Fig. 202.
Fig. 203.
Fig. 204.
68-0311—08