Underfloor heating - thermostats in basement!

I live in northern Germany and have just had underfloor heating (hot water system) installed - in a very large living room which has two heating zones and in a dining room. Screeding and insulation went in and the floors now await coverings. However a friend has just pointed out something I hadn't realised before and which now seems quite ridiculous (though maybe not you - I don't know)....

The three thermostats have been placed in the cold basement next to the boiler!

I didn't ask for this and indeed left the job to the pros. It is an old firm with many years experience. However, the more I think about it the more I believe these thermostats will not control the floor temperatures properly. Since I live in Germany I need some good ammunition first before I launch into talking to these people - I will need to take a good German speaking friend with me to see their boss.

Obviously I need to know if my suspicions are right. I also need to know what could be done to correct this. Digging up the whole floor I imagine is not an option. Could these people be made to install some kind of electronic thermostats in the two rooms connected back to electrically operated valves in the basement? Otherwise I think the whole project will be have been a total waste of thousands of euros. Thankfully I haven't paid them yet.

I had my doubts about the man who was installing when he failed to move some insulation sheets and had the plastic support sheets for the pipes dangling between a two layer thickness of insulation and a single layer (which needed the extra sheet). He said it wasn't necessary and the screeding would correct it all. This is despite the pipe tray/sheet leaning downwards at that end. I insisted it was put right - and it was- grudgingly. But I expected better of a professional. I felt sure that had that not been made level and left with an airgap the thickness of a sheet of insulation the screeding would have eventually cracked and so too my tiled floor.

Thoughts please ladies and gentlemen...which will be very gratefully received.

Zone thermostats need to be in the zone Also, multiple thermostats in the same location are pointless.

Do be sure what the multiple controls are doing though. Has this been explained to you? Do they provide programming functions? Timers and more complex controllers can be anywhere, but there needs to be something in each zone to measure the ambient temperature.

Haven't heard anything so far that would be more complex than moving some thermostats, possibly providing wireless ones if wiring is not convenient at this late stage.

These are the mechanical type thermostats almost similar in look to the radiator ones - so no programming, just a temperature ring from freezing to full on. The pipes are no longer accessible in the rooms as the floor is now screeded. They are only accessible where they come into the boiler room. This is the next room on underneath one of these rooms.

Do you know the make of these controls? Danfoss maybe?
Sounds like return temperature limiters which maintain return temperature at a constant level.

Just been to the basement. It says RTL Heimeir.

Here you go....
http://www.heimeier.com/en/PDF/Info_englisch/DV3400-18-483-01-0410-lq.pdf

Similar to the Danfoss.
They are fitted correctly I would say and used as an alternative to a more expensive mixing arrangement.

But ideally they should be supplied as a separate zone from the boiler with zone valve and timer/thermostat control.

Thanks. You've been really helpful. So it it looks like I need to give them a bit more work rather than the proverbial....
Regards from all in Westerstede.