Danfoss RET 230 User Manual page 5

The heating system will not work if a timeswitch or programmer has
switched it off.
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.
If your heating system is a boiler with radiators, there will usually
be only one room thermostat to control the whole house. But you
can have different temperatures in individual rooms by installing
thermostatic radiator valves (TRVs) on individual radiators. If
you don't have TRVs, you should choose a temperature that is
reasonable for the whole house. If you do have TRVs, you can choose
a slightly higher setting to make sure that even the coldest room
is comfortable, then prevent any overheating in other rooms by
adjusting the TRVs.
Room thermostats need a free flow of air to sense the temperature,
so they must not be covered by curtains or blocked by furniture.
Nearby electric fires, televisions, wall or table lamps may prevent the
thermostat from working properly.
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