What is leaving water temperature?

The leaving water temperature (LWT) is the temperature of the water as it exits your heat pump and flows into your heating system. It's one of the most important values for understanding how your heat pump performs.

Why does it matter?

A higher LWT means the heat pump works harder to heat the water, which uses more energy. For underfloor heating, a typical LWT is 30-35°C. For radiators, it's usually 45-55°C.

What to watch for

• LWT too high: Your heat pump is working harder than needed. Check your heating curve settings.
• LWT fluctuating rapidly: This might indicate short-cycling. The compressor is turning on and off too frequently.
• LWT not reaching setpoint: The heat pump may be undersized for your home, or outdoor temperatures are extremely low.

SmartClima shows you the leaving water temperature in real time, so you can spot these patterns before they become problems.