Thx9321 Thermostat Wiring Diagrams Using Universal Relays To Control Heating Or Cooling - Honeywell Prestige 2.0 THX9421 Manual

THX9321 Thermostat Wiring Diagrams
Using Universal Relays to Control Heating or Cooling
The THX9321 Thermostat and the EIM have universal 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 143, page 144, and page 147)
Powering universal relay with system transformer
(THX9321 shown).
Transformer
120 24
VAC VAC
HEAT STAGE 3 or
COOL STAGE 3 or
3
Fig. 331. Prestige THX9321 powering universal 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
COOL STAGE 4
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 143, page 144, and page 147)
NOTE: The EIM has dedicated terminals for
Conventional Heat Stage 3 and
Backup Heat Stage 2 for Heat Pumps
Powering universal relay with separate heating
transformer (THX9321 shown).
Transformer
Transformer
Fig. 332. Prestige THX9321 powering universal relay
with separate heating transformer.
145
120
24
C
VAC
VAC
R
2
HEAT STAGE 3
R
3
120
24
C
VAC VAC
®
IAQ WITH EIM
C
Rc
R
U1
1
U1
U2
1
U2
M32953
68-0311—07