Is the attic always colder than the ground floor?

The following information suggests that your flow rate is too low:

-only 0.3 to 0.5 K higher room temperature when increasing the flow temperature by 5 K
-generally rather high flow temperature
-it gets warmer where the coils are less tightly spaced
-pump only on 1
-coils subjectively laid too tightly

What is the difference between flow and return? Have you already tried throttling all circuits at the bottom?

It is already a bit late in the year (the heating will soon be turned off again), so this effect is lessened, but in principle I know the phenomenon described here. The original installer checked/adjusted the valves twice (according to the calculation) and has meanwhile given up on the troubleshooting. Another installer has so far said as a first diagnosis that he misses a hydraulic separator, which supposedly ensures that heat generation is decoupled from heat distribution. Allegedly costs about 2000,- EUR extra... Otherwise, as a solution approach, I have also received the advice to increase the heating curve, but that somehow can't be the solution.

Best regards

K1300S

Hello,

The flow temperature is set to a maximum of 35 degrees at -20 degrees outside temperature.

So at -20 °C outside, I find 35 °C flow temperature rather low and not high. At -20 °C, we tend to go more towards 40 °C flow temperature.

What flow temperature do you have at the current outside temperatures of 0-10 °C? You would have to go down to 25 °C flow temperature by then, heating will then slowly become really difficult. Or do you have 5 cm pipe spacing??

Best regards,

Andreas

so at -20 °C outside I find 35 °C flow temperature rather low and not high. At -20°C we tend to go towards 40 °C flow temperature

I have set a gradient of 0.2 for us.
Starting at 20° means 25° flow temperature and then at -20° it should be about 33° flow temperature.
I managed better with that than with the standard setting posted below.

+20.. 25
+15.. 26
+10.. 27
+5... 28
+0... 29
-5... 30
-10.. 31
-15.. 32
-20.. 33

By default, a gradient of 0.3 was set.
Starting at 20° means 25° flow temperature and then at -20° it should be about 33° flow temperature.

+20..23
+15.. 24.5
+10.. 26
+5... 27.5
+0... 29
-5... 30.5
-10.. 32
-15.. 33.5
-20.. 35

Hello, it is time to give an update. The heating engineer came back again. He still refuses to flush the heating circuits. His claim is that it is 100% not the cause, otherwise the circuits would have no flow at all and it wouldn't get warm at all. What is to be made of this statement? Using the thermal camera, he then went through each floor by random sampling. The interesting thing is that the floor always shows a temperature of 24.4-25 degrees. The room temperature on the ground floor and first floor is around 22.5 (room thermostat set to level 3), but in the attic, despite the same floor temperature, the room temperature is 21 degrees (set to level 6). This is absolutely illogical. Just as illogical as the increase in the flow temperature from 33 to 43 degrees only resulting in 0.2 degrees higher room temperature in the attic. When we turn all room thermostats fully up, we reach about 24,x degrees room temperature in every room, except for the attic. There it stays at 21. The explanation today was: it is due to the high humidity... the higher the humidity, the lower the temperature... that sounds like nonsense to me... He then changed the flow values again... reduced the flow on the ground and first floors, increased it in the attic by 0.5L... so far the first 18 hours have shown no improvement... the flow for all attic heating circuits is set to 2l/m. I am slowly at my wit's end. And they resist bleeding with tooth and nail... No idea what to do now. But this can't be normal?!

The room temperature on the ground floor and first floor is each around 22.5 (room thermostat set to level 3), but in the attic, despite the same floor temperature, the room temperature is at 21 degrees (set to level 6). That is absolutely not logical.

The opposite is true, that is more than logical... you have higher heat losses in the attic than on the ground floor, since you have a roof there through which the heat can escape...

But this has already been explained to you several times here.