I am not a plumber. My friend had a conservatory built and they extended her central heating but buried the flow and return pipe under the floor. There is only one flow and return pipe feeding 2 radiators so I assume they have split the pipes under the screed to feed both rads.My understanding is that the pipe should be continuous and should be housed in another pipe so it can be removed if there are any problems. Also connectors should not be buried. I am considering telling them to rip up the floor and do it correctly unless someone tells me that this is acceptable. Any help and pointers to any building regs etc would be appreciated.