Honeywell Home T4 Pro Notice D'installation page 3

Setting Slider Tabs (built-in jumper)
Set R Slider Tab.
• Use built-in jumper (R Slider Tab)
to differentiate between one or two
transformer systems.
• If there is only one R wire, and it is
connected to the R, Rc, or RH terminal, set
the slider to the up position (1 wire).
• If there is one wire connected to the R
terminal and one wire connected to the Rc
terminal, set the slider to the down position
(2 wires).
NOTE: Slider Tabs for U terminals should be
left in place for T4 Pro models.
UWP Wiring terminal designations
S
Not used for T4
thermostat.
S
Compressor contactor
Y
(stage 1)
Not used for T4
Y2
thermostat.
G
Fan
24VAC common. For 2
transformer systems,
C
use common wire from
cooling transformer.
U
Not used for T4
thermostat.
U
* Terminal can be jumped using Slider Tab. See "Setting Slider Tabs" above.
** The THP9045A1098 C-wire adaptor is used on heat/cool systems when you only
have four wires at the thermostat, and you need a fifth wire for a common wire.
Use the K terminal in place of the Y and G terminals on conventional or heat pump
systems to provide control of the fan and the compressor through a single wire—the
unused wire then becomes your common wire. See THP9045 instructions for more
information.
L/A
Not used for T4 thermostat.
- A
O/B Changeover valve
AUX -
Auxiliary heat (TH4210U
W2
only)
Emergency heat (TH4210U
E
only)
W
Heat (stage 1)
Connect to K on C-wire
K
adaptor**
24VAC power from heating
R
transformer*
24VAC power from cooling
Rc
transformer*
3
UWP Mounting System
R/Rc Slider Tab
(built-in jumper)
Note: Not all
terminals may be
used, depending
on the system
type that is being
wired. The most
commonly used
terminals are
shaded.