: Press and hold the UP arrow key for several seconds until the display flashes "tUnE" .
A comfortable and safe starting point for most domestic hot water systems is 40°C (104°F) . You can adjust up or down based on your specific needs and the season. thermotech tt91 manual hot
Is the unit actually , or is only the digital display reading hot? : Press and hold the UP arrow key
Given the unit's age, you must decide:
A digital filter that can be increased if the PV is jumping due to electrical noise. thermotech tt91 manual hot