Operation Manual

5
A typical use of the EXTRA HOUR button would be if you returned to the house for
a short period when the hot water was off. Pressing the EXTRA HOUR button gives
you 1, 2, or 3 hours of hot water, exactly when you need it. Another typical use is
when the hot water is already on and you want it to stay on a little longer - just press
EXTRA HOUR and, for that day only, an hour will be added to the end of the time at
which hot water normally goes off.
The MODE button allows you to select how you want to operate your hot water. A
typical use of this feature would be if you take a mid-week day off work, you can
then set the MODE to ONCE to keep the system ON during the day from the first
programmed ON time till the last programmed OFF time.
Your Cylinder Thermostat
Your CS92A wireless cylinder thermostat measures the water temperature and signals
this to the ST9120C timer. The timer then performs all the necessary control actions to
maintain the water temperature at the set value. The set temperature is programmed by
your Installer in the ST9120C Installer Mode, and you should never need to change this.
A value of 60°C is typical.
CONTROL OF YOUR SYSTEM (CONT.)