UFH controlled by return temperature

[JohnMo]

18 hours ago, LukasV said:

Correct? Please say that I am correct!

I think you are looking at steady state, which is only one set of circumstances.

 

The floor energy output is its area and floor surface to room dT. As the heat demand increases because it's colder outside, the only variable to output is floor to room dT. So floor temperature has to increase to compensate for additional heat losses. That is why weather compensation exists. On a set flow temperature I can charge the floor for 2 hours on a mild day and the house stays warm all day. On a very cold day heating runs all day.

 

So you either need to change how long you add heat or flow temperature or both to compensate for different floor output required.

 

Maintaining a set flow return dT will just give a fixed output which only meet one fixed output kW.