Unit installation

DCN: 141-00885-16 1/26/06 TZ40 Thermostat Manual 7
Thermostat Control Screen
Thermostat Control Screen - LED Displays
The Thermostat Control Screen has the following LED labels and descriptions, numbered from top to
bottom, 1-4.
o LED 1 Green: System Operation display.
o LED Off, “SYS OFF” displayed > HVAC system is OFF
o LED Off, “SYS MOT” displayed > Minimum Off Time (MOT) delay on is active
o LED On, “SYS ON” displayed > HVAC System is running
o LED On, “SYS MRT” displayed > Minimum Run Time (MRT) delay off is active
o LED 2 Green: System Economy Mode display
o LED OFF or On, “Econ” displayed > Economy or 1
st
stage heating or cooling only
o LED On, “2
nd
Stg” displayed > Stage 2 heating or cooling is active
o LED On, “3
rd
Stg” displayed > Stage 3 heating is active
o LED On, “Vent” displayed > fresh air venting is active
o LED 3 Green: Run/Hold display. Shows state of Schedule Run/Hold Mode.
o LED Off, “Run” displayed > Schedule is running
o LED On, “Hold” displayed > Schedule is off, temperature setpoint hold in effect.
o LED 4 RED: Alert LED. Used for Messaging and other system alerts
o LED Off, “No Msg” displayed > No text messages or Alerts present
o LED On, Mail icon or Alert Text displayed > Message waiting or specific alert text
“Communications Error” Display
If the WDU is not properly wired or if communications to the Control Unit is interrupted, the LCD display
will flash “Comm Failure” at the top center of the Thermostat Control Screen (where outside temperature
is normally displayed) . Momentary display of “Communications Failure” caused by loss of data, will clear
automatically when data communication is restored. If the “Communications Failure” display stays on,
check wiring or control unit for problems.