Due to the oxygen diffusion through the capillary tube, a system separation of primary and secondary circuit is essential.
Even tubing and copper systems should be based on a separation system. Only by this separation it can be guaranteed that no corrosion particles of the main system can find its way into the cooling ceiling. For reasons of cost, a system separation for the tubing and copper systems is often omitted.
The separation is effected by a transfer station, which includes components like a stainless steel heat exchanger, circulating pump, expansion tank with cap valve, safety valves, isolation valves, thermometer and manometer. All the water-filled components that are used in the capillary tube system are corrosion resistant on the secondary side. This implies that the water quality remains in a good quality for a very long time.
For the separation systems, there are two different versions:
In many cases it may be advisable to decentralize distribution and control of the volume flows of the secondary side. The control units of the individual zones are connected to a distribution pipeline. The control units of the individual zones are located either in the accessible ceiling of the hallway or over the corresponding inspection flaps in rooms with radiant panel heating/cooling. For maintenance and checkup of the volume flows of individual zones, all positions of the valve groups must be inspected which is quite time-consuming.
In this more complex but more user-friendly version, each control zone with supply and return lines is connected to the distributor at the transfer station. The adjustment and control of the volume flows may be done centrally.