Danfoss RT51 Instructions D'installation Et D'utilisation page 5

Prior to mounting the unit should be set in either ON/OFF or
GB
chrono-proportional control mode (see below).
ON/OFF CHRONO
ON/OFF - boilers switches ON when below set temperature
and OFF when above.
Chrono-Proportional - energy saving feature which fi res
the boiler at regular intervals to maintain a set temperature,
achieving a constant ambient environment for the user.
!
Some existing thermostats will have a Neutral wire and/or
Earth wire connected. These are not required by the RT51/52
and must NOT be connected to any RT51/52 terminals. Instead
they should be made electrically safe and coiled in the recess at
the back of the RT51/52.
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