INSTALLATION
Please read the important safety information at the start of this manual before you start to install the
device.
The ideal position to locate the ST320 thermostat is about 1.5m above floor level. It should be
mounted in a location where the thermostat is accessible, reasonably lit and free from extremes of
temperature and draughts. Do not mount the thermostat on an outside wall, above a radiator or in
a location where it may be subjected to direct sunlight.
There are only two electrical connections required to the
ST320, and these connections should be made to the
terminal block inside the thermostat. No Earth
connection is required for the correct and safe operation
of the ST320, but a parking terminal is provided to
connect an Earth wire if one is present. These connections
are shown in the drawing and table below:
Terminal Function
L (COM) Live
SL (NO) Switched Live (output)
Earth Earth Parking (No electrical connection)
NOTE: All electrical installation work should be carried out by a suitably qualified Electrician or other
competent person.
If you are not sure how to install this thermostat consult either with a qualified electrician, heating
engineer or your boiler / heating system supplier for advice on how to continue.
