DHW CIRCULATION MANAGEMENT

The main function of Domestic Hot Water re-circulation in plumbing systems is to control that there is no unnecessary waste of the domestic water consumed, plus it keeps the water temperature constant along the line. 

Re-circulation creates a loop from the hot water supply point (typically a storage tank) to the bathroom fixtures (taps, showers, etc.) and vice versa. Thus, when hot water taps are opened, it will arrive quickly, avoiding wastes. Typically managed by a timetable time slots, it should be activated at those times when there has been no withdrawal for many hours and therefore the water inside the pipes has cooled. It is usually activated early in the morning before people wake up and in the evening before people return from work, so that when the tap is turned on, the water is already warm and usable. 

This avoids wasting cold water (contained in the pipes) while waiting for hot water to arrive from the storage tank. It would also be a waste not to have a timer associated with the re-circulation, in fact in this case the re-circulation water pump would always be switched on with a consequent increase in electricity consumption.

Re-circulation pipe can be inserted either in the storage tank or directly on the cold sanitary water inlet of the thermostatic mixer, the choice depending on various factors (availability of connections on the storage tank, available space):

The REG System manages re-circulation by default through timetable and particularly through the timetable associated with the DHW subsystem:

When the DHW timetable is in Comfort mode, the recycle is activated, triggering digital output 50, which must give consent to the re-circulation water pump:

If you want to release the re-circulation timetable from the DHW timetable, you must create a zone to act as a circulation, then on the Zones page associate a free zone with a timetable (do not associate circuit, dehumidifiers or integration):

Remember to set the DHW mode as work Special Mode of the zone dedicated to the re-circulation water pump in Configuration Zone / 3:

The timetable can be set as indicated below:

It is also possible to refine the re-circulation control by adding a water temperature probe to the re-circulation pipe so that the circulation starts at the times indicated by the timetable, but only if the probe temperature is below a certain value (for example, 38°C):

Then you proceed by associating a probe to the circulation zone as in the previous image and set the set point on the Zone Parameters page:

Setting 38°C means that only below 38°C (and at the times when the timetable is turned on) the zone will be active and turn on the re-circulation water pump, which must be associated with the output of the zone itself, in the example shown is the zone 1:

Output 50 must not be used in this case.

Finally, the circulation will be switched off either you are outside the set times, and also when the probe temperature exceeds the set point (38°C) plus the hysteresis set in the DHW page:

In the example shown the hysteresis is 3 K, therefore the circulation could switch off even when the probe detects a temperature higher than 41°C.