LockState Connect LS-24VAC 24 Vac Adaptor for LS-90i;

The 24VAC power adapter will provide power to the LS-60(i) and LS-90(i) from any standard electrical outlet.  This can be used if you do not have an existing C-Wire coming up from your furnace to your thermostat.  This transformer converts 110VAC to 24VAC for use with LS-60(i) and LS-90(i) thermostats.  Simply connect one end to the "Rh" terminal and the other end to the "C" terminal.  You can connect either wire to either terminal (there is no polarity).