KB-7 - Danfoss is slow to react to changes

Question

The Danfoss Living Connect Radiator Thermostat is very slow to react to changes and / or opens the radiator valve slowly.

Answer

This is actually by design, it's called "intelligent heating control"!

Solution

There's generally three elements involved in the operation of electro-mechanical TRVs.

  • Set-Point - the temperature that you want the room to reach.
  • Temperature - the current temperature as measured in the ambient air around where the TRV is installed.
  • Percentage Of Valve Opening - how far the valve is currently open.

With the above points in mind, here's how the Danfoss typically work:

  • You change the Set-Point to 22 °C, either manually or via the Z-Wave controller (for example from a Scene).
  • The Danfoss looks at the current Temperature of 18 °C and the fact that the valve is currently open 1%.
  • Using it's internal logic and algorithms, the Danfoss determines that over the next XX minutes it will open the valve incrementally by X% at a time.
  • The Danfoss continually checks and adjusts itself based on how the Temperature reacts to each change in valve open percentage.
  • Eventually the Set-Point is reached and the Danfoss will continue to monitor and adjust itself to maintain the Temperature.

The above process is designed to intelligently control your heating and prevent rapid temperature rises and fluctuations due to overshooting the Set-Point.

For more information on controlling heating, please see our application notes Creating a Heating control system with Vera and Creating Heating Zones.