From time to time, the DSL thermostats have been known to lock up. This is normally caused by a lightning storm or electrical surge.

Normally when locked up the thermostat will not operate the Hydro-Temp system and will display 28 degrees.

To reset the DSL thermostat:

1. Raise the button cover.
2. Press and hold down the Mode button, until the display changes to four zeros. This will normally take approx. 10 seconds.
3. Next press and release the mode button 4 times.
4. Wait approx. five seconds. The four zeros will change to read the current room temperature in degrees Celsius.
5. You can then press the temperature up and temperature down buttons at the exact same time (once) and this will change the temperature read out to Fahrenheit.
6. You will now need to reset the desired room temperature for heating and cooling.