Hey Vlad,
When you were putting in these floors:
...did you use stamped transfer plates like this:
...or did you use an extruded transfer plate like this:
The reason I'm asking is that in my investigations of high performance radiant floors, the thickness of the aluminum seems to have a very large impact. For instance, Warmboard has higher specs than any similar product, and the only difference I can see is that it has a thicker aluminum layer... like .025" instead of .008" or .012" or .018" as the other products had.
The extruded aluminum spreader plates are an amazing .062" thick, compared to the typical .018" that is usually seen in stamped spreader plates. Their price is higher by almost exactly the same ratio of thickness, too.
Also I am wondering if your floors make the popping noise I have read about?
Did you use oxygen barrier coated PEX or PEX-Al-PEX?
-AC