Recommended spacing between cables using 2 in 1 UFH/Decoupling Mat

[hhh1234]

Using Dural CI- FH and have it laid down. Looking to tile the entire flat with the T2 Universal Black wire by Raychem

Unsure what to go for re spacing between the cable runs. Popular seems to be 3 towers (70mm apart) which I believe equates to 150w/sq m .
Would 2 towers apart (50mm spacing) lead to possible overheating in the future and tile damage due to reckless tenants? Or would 3 tower spacing not be sufficient heating?

 

[Andrew Owens]

With underfloor heating matting they are 50mm stuck on the mesh. With loose wire you could go 70mm if it's 150w or 200w, just make sure the wires don't get closer than 50mm