The Way To Use A Room Thermostat; Optimisation - Honeywell Y9120H Sundial RF2 Pack 1 User Manual

CONTROL OF YOUR SYSTEM (CONT.)
the heating 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
heating normally goes off.
The MODE button allows you to select how you want to operate your heating. The
most obvious use is to switch heating OFF during the summer months, but you may
also use this feature 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.

The way to use a Room Thermostat

The way to set and use your room thermostat is to find the lowest temperature setting
that you are comfortable with, and then leave it alone to do its job. The best way to do
this is to set the room thermostat to a low temperature – say 18°C – and then turn it
up by one degree each day until you are comfortable with the temperature. You won't
have to adjust the thermostat further. Any adjustment above this setting will waste
energy and cost you more money.
DT92E has a green ECO button, which enables you to set a period of time at a lower
temperature. This energy saving feature is most useful if you are out of the house for
a few hours, or if you want a reduced temperature for a while and don't want to have
to remember to turn the temperature back up (see pages 22 & 23 for details).
Optimisation (see page 17 for explanatory diagrams)
Your control system has some features called Optimisation, which aim to save
energy while making you as comfortable as possible. These may or may not be
enabled – check page 30 where your Installer should have indicated how these were
set. Optimisation does not apply to your Hot Water, only to your Heating and will
only work if you have a DT92E in your system.
Optimum Start works by measuring how quickly your system normally heats up, and
using this to calculate the correct time to switch on to reach your comfort temperature,
when you want it. So the times you set are when you want the heating to be at the
correct temperature, and the system adjusts the starting time to meet this.
Delayed Start is an alternative to Optimum Start. It works by using your normal
programmed start times, compares the actual temperature with the set temperature, and
delays the start a little depending on how close these temperatures are to each other.
Optimum Stop saves energy, and money, by switching off a little earlier than the
normal programme time. If the house is up to temperature, you will not notice the
effect on the temperature, but you will see a difference in your fuel bill.
The radiator symbol on ST9120C will flash to let you know whenever Optimisation
is operating.
The other controls in your system should not require adjustment.
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