Has anyone had any experience with a German UFH system where, instead of a 60mm+ screed on top of the pipe, the pipe sits in a pre-formed groove in heavy clay/kiln-burnt carrier tiles (approx 40mm thick), which sit atop the insulation layer and are aligned with oak pegs?
The finished floor - usually a ceramic or marble tile - is bedded directly onto the top of the carrier tile, ergo you can feel heat more quickly, which stands to reason. The importers also claim lower energy input and flow temps than normal wet UFH to achieve the same result, with much quicker heat-up times, one of the downsides of UFH.
I just finished my first job with such a system, at a client's request. A bit fiddly, as the pipe ends (the bends) are not encased and have to be clipped to the insulation, and the floor level made up to tile height with a clay-mix aggregate. My concerns, as there is so little weight on top of the pipes, is the physical/annular strength and stability of the floor under heat. Plus the system is designed around a linear model where I prefer bifular (snail) due to its more even heat-spread. Those concerns having been relayed to the client, I am prepared to try anything which leads to lower fuel bills, or less logs - for those lucky enough to have them!
If anyone has had any experience with such a system, any feedback would be welcome.