Operation Manual

4
General Description of Controls in Your System
Your Honeywell ST9120C provides timing control for your hot water system, letting
you set ON and OFF periods to suit your own lifestyle.
The ST9120C does not directly control the temperature but works together with a
CS92A wireless cylinder thermostat.
With 7-day programming and up to 3 on/off periods per day, every day can be set
differently.
ST9120C also has a Boiler Service reminder / Shut-down feature, which helps
ensure your gas boiler is regularly serviced in compliance with UK Gas Safety
Regulations. For more details see pages 18 & 19.
Your system includes a CS92A wireless cylinder thermostat and may include
other Honeywell wireless controls. These products use state of the art 2 way RF
communications to share information and give you robust and flexible control of your
indoor environment.
The following instructions explain how to programme and use the ST9120C, and
associated controls, to provide the most home comfort at the least cost.
The way to use a Timer
Think about the time periods when you are typically in the house and when you are not.
These are the times you should use as the basis for the programmes. It will be necessary
to allow some heat up time for the heating system after periods when it has been off – this
would typically be 1 - 1½ hours, depending on your house and your preferences.
Other features are commonly available on the Timer to enhance comfort and
convenience, for example, OVERRIDE, EXTRA HOUR, and MODE buttons.
A typical use of the OVERRIDE feature is when you return home unexpectedly for
the rest of the day and the hot water is off. Just press the OVERRIDE button and
the hot water will come on until the next programme time, at which point it will follow
the normal programme. The advantage here is that you do not have to remember to
switch off because the normal time programme does this for you.
CONTROL OF YOUR SYSTEM