ᐅ Adjusting Underfloor Heating – Is It Malfunctioning?

You are right. I can turn the glass, but it doesn't change anything.
I can remove the gray part on top.
I have slightly turned the knob underneath. Let's see if anything happens.

ArniBanarni schrieb:

I slightly turned up the knob underneath.

It works like a thermostat for a radiator. You have the pin in the center. It is pushed in by the motor or can extend outward. This controls the flow rate. You can adjust it to fine-tune.

Ah, great, I got it. I have the feeling that the bathroom floor is just cold now, not ice cold anymore. Let’s wait until this evening or tomorrow to see if anything changes.

Does the sight glass now show flow? Otherwise, turn it fully counterclockwise.

Only the middle sight glass shows flow. However, flow was present in all other rooms except the bathroom.

At the location indicated, I turned counterclockwise, opposite the screwdriver's direction. The red parts at the bottom cannot be turned; only the white plastic around them can be rotated.

I am also wondering: is the bathroom connected to the hose on the right or the second from the left, since the hose is labeled with a "5"?

Ah, I have now found the key for the red ones.
All of them are fully turned "on" counterclockwise?
I adjusted them a bit clockwise.