Temperature zones may be set in either Fahrenheit or Celsius degrees. The default temperature scale is Fahrenheit. To change to Celsius: 1. Press SENSOR ON/OFF. 2. Press °F / °C. The Model 400 responds: “Degrees Celsius” indicating Celsius scale has replaced Fahrenheit scale. 3. To return to Fahrenheit scale, repeat the key sequence. The Model 400 responds: […]