Think roads for the traffic of heated and spent water.

Different materials can be used to run the stream of luxuriant heat around your home, often;

Copper – Great transfer of heat energy, but expensive and more likely to corrode over time than...

Plastic (PVC) – Or multi-layer, often the best and most used.

Steel – expensive and very in-flexible, mostly used in Manifold construction.

This piping is then laid in formation to provide the best expression of the heated water in the pipes.
It is installed in one of three ways;

In Slab Hydronic Piping

Piping is laid inside the foundation slab.

Screed

An insulating layer is laid on the slab, the piping is placed on top of this layer and another layer of slab material is laid on top. This top layer (above the insulating layer) is called the screed.

On top (of slab)

This is where a piping network is placed between an existing slab and a floor. The flooring material can be timber, slate or even another layer of concrete. The piping is laid in a supporting steel housing in this method.