User Manual

Page 10
activate the SMT-131 internal door bell.
Regardless of the need to control conferential HVAC systems, 2 or 4 pipe fan coils with
modulating valves the SMT-131 has the necessary outputs to achieve your control needs.
Occupancy Detection
The SMT-131 has sophisticated logic
that when connected to your choice
of movement sensors, door and
window switches will automatically
control the set point and mode of
the SMT-131.
Using part or all the functions
described below are completely
optional. The SMT-131 will function
perfectly as a HVAC controller without the door, window or occupancy detection logic enabled.
There are two types of occupancy detection modes provided by the SMT-131, see latched
occupancy detection on page 11 or PIR only occupancy detection on page 12 of this manual.
DO NOT APPLY EXTERNAL VOLTAGES TO THESE INPUTS
Window Contact
The window contact input (WC) is used to automatically disable the HVAC system if a window is
left open. This is done to prevent energy waste by trying to heat or cool an open room.
The SMT-131 window input can be set for a Normally Open (switch open when window is closed)
or normally closed logic (switch closed when window is closed). When the window is left open for
longer than the pre-set time (0 to 300 seconds) the SMT-131 will automatically turn OFF. The text
“OFF” will flash in the LCD to indicate that the remote window (or door switch) is holding the
SMT-131 in off mode. The wall controller will prohibit all changes.
The SMT-131 will automatically restart once the window is closed.
The Installer menu option 28 “Window Input Logic” and option 29 “Window Input Delay”
(page17) sets the window detection logic in the SMT-131.
Fault Indication
The SMT-131 can display the text “FLt” alternating with the temperature should you wish to alert
the user of an external fault with the heating or cooling system.
To enable this function, enter the installer menu and set the Window contact input setting 31 to
option 3. (See page 17 for this setting).
When the WC terminal and the Com-0V terminal are joined the SMT-131 will alternate “FLt” with
the current room temperature.
Register 32 will permit a time delay to be set after the fault signal is received if necessary to
reduce false trips.
The fault indication has NO effect on thermostat function