9
Using universal relays to control heating or cooling
(Prestige and RedLINK VisionPRO models only.)
U1/U2/U3 terminals are normally open dry contacts when set up for a stage
of heating or cooling.
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.
Dry contact alerts
(Prestige and RedLINK VisionPRO models only.)
EQUIPMENT DAMAGE HAZARD.
Do not apply power to S1–S4 terminals.
Do not connect a temperature sensor to the S1–S4 terminals if set for a dry
contact device.
NOTE:
The dry contact device must be rated for low voltage.
If you are not using the S1–S4 terminals on the EIM, you can connect them to
a dry contact device to display an alert. Dry contact alerts include Full Drain
Pan, Dirty Filter, Water Leak, System Shutdown, Service Needed, Fan Failure and
Custom Alert. Dry contact device can be normally open (shown in diagram) or
normally closed.
NOTE:
You can connect multiple Dry Contact devices in parallel to the S1–S4
terminals.
MULTIPLE DRY CONTACT DEVICES
ON ONE SET OF TERMINALS
EIM
M34252B
ONE DRY CONTACT DEVICE
S4
S4
S3
S3
1
M39128
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
1
2
MULTIPLE DRY CONTACT DEVICES
ON ONE SET OF TERMINALS
ONE DRY CONTACT DEVICE
S2
S2
S1
S1
EIM
M39125
