Unfortunately , this is one of the issues with underfloor heating. The pipework is often sealed in someway under Neath a flooring surface. Underfloor heating is often placed in a concrete screed . the pipe work should be pressurised and tested before this to check the pipework for leaks before covering and also left pressurised when covered to allow for pipe expansion when the system is hot. Your plumber will know if secondary circulation is necessary , if qualified or experienced .I have fitted it in multi bathroom situations. You have to remember it saves a few seconds of running the hot tap but costs a lot energy wise as the pump is continuously circulating hot water that cools and then has to be reheated.
Thnak you. Any suggestions as to what can be used to cover the insulated pipes between the celotex(hot and cold feeds from 2 manifolds and water pipe 28mm all insulated)
is it ok to pour screed in this area which is a 100mm ditch between celotex and on top of DPC
Yes , its fine to pour the screed on top of the dpc. To be honest the pipes don't have to be covered. The one thing you don't want is to do all this work and find that you are just not getting any heat out of the underfloor heating .. The screed is supposed to be in direct contact with the pipework so the whole screed heats up as a block . I found a website that can show you this being done in action .