Tilemaster thermal delta board? - Tile Advice

[bayhorse123]

I am looking to lay mesh underfloor heating on a bathroom floor.

Currently there are old rank floorboards. I have found these boards at screedgiant:

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www.screedgiant.co.uk

Are these any good? How would they compare to the pro warm backer board?

Would I lay these ontop of the old floorboards and screw through to the joists or should I put down t&g chipboard first then adhesive then the thermal board and so on??

Thanks in advance!