From firmware version 4.28 of the REG-DIN-8 and 4.28 of the RegConfig, the Surplus function is available, which allows the setpoint of the zones and the DHW subsystem to be changed under certain conditions.
In Configuration 1, an input on the Surplus channel must be set: when this contact is closed (if set NA) or opened (if set NC), Surplus will be activated.
This signal can come from the photovoltaic system in the event of energetic surplus, or from a controller that measures the energy from the photovoltaic system and the consumption of electrical energy absorbed by the house loads sends a signal to the controller if there is a surplus:
Zones Surplus
One the Zones page, select Zone/3 Configuration:
The Surplus Regime determines, according to the priority assigned to the zone (High, Medium, Low, None), which one is promoted first from the Economy to Comfort. So, assuming we have 3 zones:
zone 1 with priority None
zone 2 with priority Low
zone 3 with priority High
At the moment the contact closes, the first zone that will switch from Economy mode to Comfort mode is zone 3, assuming the Economy set point is already satisfied. When zone 3 has reached the Comfort set point, zone 2 is promoted to Comfort and so on.
This logic applies both in Summer and in Winter.
At the moment you want to exploit this logic, the zones must be programmed accordingly: it does not make sense to have all the zones always in Comfort, but it makes sense to have them mainly or always in Economy (with set point that are in any case reasonable).
DHW Subsystem Surplus
In a similar way it is possible to give priority to the DHW Subsystem (None, Low, Medium, or High):
The logic is always to switch from Economy (if the economy set point is already satisfied) to Comfort.
There is no priority between DHW and the zones, therefore with equal priority they are promoted at the same time, without giving priority to the domestic hot water.
For example, assume that the zone and the DHW are in Economy with relative set point satisfied, and the priorities assigned are:
Zone 1 → High
Zone 2 → High
Zone 3 → Low
Zone 4 → Medium
Zone 5 → None
DHW → Medium
Now let’s assume that the Surplus contact closes, the order of switching to Comfort is as follow:
Zone 1 and Zone 2 → Comfort, once they both meet the Comfort set point
DHW and Zone 4 → Comfort, once they both meet the Comfort set point
Zone 3 → Comfort
Zone 5 will remain in Economy or in Comfort according to the programming as it is not affected by this logic.
In the event that, once the zones with Medium priority have been promoted to Comfort, and the room temperature of one of the zones with High priority no longer meet the Comfort set point, the zones with Medium priority will be put back into Economy and the system will attempt to meet again the Comfort set point of the High priority zones no longer reached.