Underfloor heating - the control panel does not work, cold return

Hello, I am struggling with the problem of non-functioning floor heating, the pump works, the pipes in the floor permeable, the power supply warm and cold return - even when I give the pump to the max. Does anyone know what the reason for this may be?

In general, the floor heating is long heating up, so to have a return similar to the power supply, the heating can last for a few days of heating non-stop. Possibly something wrongly done or adjusted.

The layout is probably new? Is there any other heating in the building, or just this 1 loop?
As a colleague wrote above - heating the flooring takes a long time. The more so because the temperature on the thermometer is around 25 ° C.
And the thermostatic mixing valve - the one under the pump - is what value set?
Maybe you need to increase the temperature on it?
And what is the temperature in the rest of the CO system (on the boiler)?

the floor heating works at max. 40 degrees for some 3 days and nothing even flips back all the time the cold valve was previously set to 32 degrees.

Added after 6 [minutes]:

in one of the posts on the electro I read that the power should be at the bottom and back at the top yet a colleague there wrote that the power and return from the oven should be on separate sections, one at the bottom and the other at the top.
Centrala I bought a complete rally in the store, I'm surprised why not a work.
I will add that if I screw the valve on the loop, the flow drops and grows when I unscrew it the same happens as I turn the main back

The pump works, but what is the characteristic set and on which gear it is running?

the pump runs on the 2nd or 3rd gear and then the flow indicates 5 l / m, ie the maximum of the whole day, the temperature of 40 degrees and the cold return.

I suppose that these more loops are for the future, so the building is slightly larger than one room. A surety not yet insulated.
One loop does not heat up more than 10-12m2 (and in an insulated room), so do not be surprised that it is permanently under-heated and will always come back cold especially when powering 40 degrees Celsius.
You want to heat up a little, let go 50-60 st directly into the circuit, you can not leave it without control for more than a few hours.

It is important for a floor-standing floor that the pump is set in a constant-pressure characteristic, because the floor-standing unit has high resistance. If it's in customization mode or some auto-upload, there may be problems.

the room is 17 m is the kitchen so under the furniture there are no pipes from the floor-tile in this room there is still a heater with a thermostat the pump works in 2nd gear and it is constant gear so the pressure will be constant

Kolego @ kamyk828 You have not written anything about the deployment of the installation. While your distributor system is below the level of the heated kitchen floor, you have 100% aerated kitchen coil and heating will not work. The solution to the problem is to mount additional vents at the kitchen floor level. If you have access to the heating tube at the level of the kitchen floor, the easiest way to cut this pipe is to insert a tee, connecting the cut pipe and to the third stub, install a vent such as a radiator and point it up. It gives the possibility of venting the system and its operation. Air bubbles cause a significant flow resistance, which, combined with the length of the loop, prevents any flow.
While this green hose connected to the bottom beam serves to complete the system, try loosening the loop tube on the top bar and unscrewing the water supply and you will find out that I am right with this aeration while venting partially the loop.
As Kolega @Andrzej_;) lukaszewicz wrote, increase the temperature on the intake to at least 60 degrees, close the other radiators and set the pump to max efficiency. If you manage to vent the loop, after about 30-60 min you should notice an increase in the floor temperature.
Personally, I'm not a fan of mixing valves. According to me, it is more reasonable to use each loop of RTL valves on the outlet or in the case of "unheated" as I used ordinary thermostatic radiator valves mounted on the intake of each loop with a capillary mounted on the return of the appropriate loop which works and is much cheaper allowing to regulate each loop separately - checked.

colleagues, the central is above the floor level, otherwise the heating of the radiators works properly

Kolego @ kamyk828 do not try to just increase the temperature and efficiency of the pump as you are so sure about the proper ventilation of the loop.
Loop tubes can withstand temperatures of 60 degrees and can work all the time. The floor should not be hot, but by supplying it with a temperature of 40 ° C in the current weather, you will not be able to heat this floor - this is not perpetual motion.

Kolego @ kamyk828 Have you already warmed the floor ?. Your information does not indicate what you are heating up the entire system. This mixing valve makes sense when using a furnace for solid fuels because it is to prevent overheating of the heating loops.
If the system is supplied solely from the gas furnace, the mixing valve is completely unnecessary because you set the desired temperature on the furnace. In the case of feeding only from the gas furnace, the mixing valve is set to max and the temperature in the circuit on the stove. You still have the option of controlling the gas furnace from an external sensor. The colder the outside, the higher the temperature in the cycle - the weather curve. Greetings.

of course it was necessary to warm the floor well and return warm.
Greetings.