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Drainback / Low-Flow
Drainback systems
When the system is not running, for whatever reason be it a powercut, at night time or in high temperature safety mode, the gravity-aided drainback system means the panels and pipes are emptied of fluid and the system is in a passively safe and optimum security state.
When the control unit calculates that the temperature in the solar panels is higher than the temperature in the water tank, it activates the pump which sends the heat-transport fluid to the panels in order to absorb more solar energy.
When the system is on, the tank's exchanger acts as an expansion vessel since the air contained in the circuit is moved to the first coils of the heat exchanger.
When the programmed temperature is reached or when the sunlight is no longer at optimal intensity, the pump turns itself off and the fluid drains back towards the tank's solar heat exchanger. This prevents any risk of the fluid in the panels overheating.
Low-Flow
The low flow rate in the ESE solar circuit maximises the delta T° (the temperature difference between the panel inlet and outlet), which improves thermal stratification within the water tank.