Thx9321 Thermostat Wiring Diagrams Using Iaq Relays To Control Heating Or Cooling - Honeywell Home THX9321 Prestige 2.0 Manual

THX9321 Thermostat Wiring Diagrams
Using IAQ Relays to Control Heating or Cooling
The THX9321 Thermostat and the EIM have outputs that can be configured for the following stages of heating and cooling,
based on the terminals available.
THX9321 THERMOSTAT (U1 AND U2)
• Cool Stage 3 (ISU 2080 - commercial only)
• Cool Stage 4 (ISU 2090 - commercial only)
• Conventional Heat Stage 3 (ISU 2100, 2140)
• Backup Heat Stage 2 for Heat Pumps (ISU 2170)
• Geothermal Radiant Heat (see wiring diagrams on
page 139, page 140, and page 143)
Powering relay with system transformer (THX9321 shown).
Transformer
120
24
VAC
VAC
HEAT STAGE 3 or
COOL STAGE 3 or
COOL STAGE 4
3
Fig. 331. Prestige THX9321 powering relay with system
transformer.
1 U1/U2/U3 terminals are normally open dry contacts when set up for a stage of heating or cooling.
2 You must install a field jumper if the stage of heating or cooling is powered by system transformer. Do NOT install a field
jumper if the stage of heating has its own transformer.
3 U1/U2/U3 terminals are assigned to a stage of heating or cooling in the Installer Setup.
C
R
C
Rc
R
2
U1
1
U1
U2
1
U2
M32952A
®
THX9321 PRESTIGE 2.0 AND THX9421 PRESTIGE
FOR THX9421 WITH EIM (U1, U2, AND U3)
• Cool Stage 3 (ISU 2080 - commercial only)
• Cool Stage 4 (ISU 2090 - commercial only)
• Geothermal Radiant Heat (see wiring diagrams on
page 139, page 140, and page 143)
NOTE: The EIM has dedicated terminals for
Conventional Heat Stage 3 and
Backup Heat Stage 2 for Heat Pumps
Powering relay with separate heating transformer
(THX9321 shown).
Transformer
120
VAC
Transformer
120
VAC
Fig. 332. Prestige THX9321 powering relay with separate
heating transformer.
141
®
IAQ WITH EIM
24
C
VAC
R
C
Rc
R
2
U1
HEAT STAGE 3
U1
R
3 U2
24
C
VAC
U2
M32953
1
1
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