Honeywell Prestige IAQ YTHX9421 - Wiring Dry Contact Devices to Display Alerts; Connecting a Stage of Heating or Cooling to a Universal Relay (U1, U2, U3)

4
Terminal Designations
Conventional System Heat Pump
Terminal Description Terminal Description
U1 / U1**
U2 / U2**
U3 / U3**
Universal relay for humidification,
dehumidification, ventilation, or
a stage of heating/cooling. U
terminals are dry contacts that
require power.
U1 / U1**
U2 / U2**
U3 / U3**
Universal relay for humidification,
dehumidification, ventilation, or
a stage of heating/cooling. U
terminals are dry contacts that
require power.
S1 / S1***
S2 / S2***
S3 / S3***
S4 / S4***
Universal input for a wired indoor
sensor, outdoor sensor, discharge
sensor, return sensor, dry contact
device for alerts or dry contact
device for remote setback.
S1 / S1***
S2 / S2***
S3 / S3***
S4 / S4***
Universal input for a wired indoor
sensor, outdoor sensor, discharge
sensor, return sensor, dry contact
device for alerts or dry contact
device for remote setback.
A
B
C
D
Connect to THM4000R1000
Wireless Adapter for extended
wireless range.
A
B
C
D
Connect to THM4000R1000
Wireless Adapter for extended
wireless range.
** See wiring diagrams on pages 4-5.
*** See wiring diagram below for wiring Dry Contact Devices to display alerts.
U1, U2, and U3 are normally
open dry contacts when set up
for a stage of heating or cooling.
Youmustinstallaeldjumperif
the stage of heating or cooling is
powered by the system trans-
former.DoNOTinstallaeld
jumper if the stage of heating has
its own transformer.
1
2
1
2
U3
U3
U2
U2
U1
U1
120
VAC
24
VAC
24
VAC
HEAT STAGE 3,
COOL STAGE 3,
COOL STAGE 4 OR
GEOTHERMAL
RADIANT HEAT
RH
RC
R
C
TRANSFORMER
Wiring dry contact devices to display alerts
DISCONNECT POWER BEFORE INSTALLATION.
Do not apply power to S1, S2, S3 or S4 terminals.
NOTE: The dry contact device must
be rated for low voltage.
Connect a dry contact device such as a
water sensor to S1, S2, S3 or S4 terminals.
The thermostat displays an alert when a
problem is detected.
MULTIPLE DRY CONTACT DEVICES
ON ONE SET OF TERMINALS
EIM
ONE DRY CONTACT DEVICE
Connecting a stage of heating or cooling to a universal relay
(U1, U2, U3)