Are you installing "radiant " heating ?
Or just warming your floor?
I really don't know much about this but if radiant is still an option you should look into it. But I am sure it is much more expensive. But a super way to save on energy bills.
Warming a floor, cool, price sounds okay. Are they providing the materials?
There is probably a ratio for plumbers.
Number of fittings = equals labour x time x parts
oh I have no idea what I am talking about.