When is it necessary to control the auxiliary heating with Dualsun solar controller?

Edited

We distinguish below the cases where the control of the back-up is necessary so as not to hamper the operation of the solar installation.

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Case 1: 

Boiler exchanger loop at the top of the tank: no direct conflict between the heating layers. 

⇒ Non-justified back-up control

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Case 2: 

The electric resistance works in the middle-top of the tank: no direct conflict between the heating layers. 

⇒ Non-justified back-up control

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Case 3: 

Boiler exchanger loop in the middle of the tank: direct conflict between the heating layers. 

⇒ Control of the back-up necessary or installation of a preheating tank dedicated to solar


Note: Monobloc thermodynamic water heating tanks often have the solar and auxiliary thermodynamic heat exchangers stacked on top of each other.

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Case 4: 

The electrical heater is slightly above the solar exchanger and the S2 probe is placed at the same level as the electrical heater. Heating the electric resistance may affect the value of the S2 probe and stop the solar pump. 

Control of the back-up necessary or installation of a preheating tank dedicated to solar