Danfoss RET 230 HCW-3 Installation Instructions Manual page 8

DIL Switch descriptions
Switch 4: If set to On/Off, both heating and cooling stages
Switch 3: Active only if switch 4 is set to Chrono. This
Switch 2: Allows Celsius or Fahrenheit temperature scaling
Switch 1: Not used in this model
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operate in on/off mode. If set to Chrono, heating
stage operates in chrono-proportional modes,
cooling continues in On/off mode
switch determines the number of cycles per hour
that the thermostat will impose on the system,
the options are three 20 minute cycles or six 10
minute cycles
to be selected