How to check and change a circulator on a solar station SLL?

1. Diagnosis of circulator operation

a) Checking the power supply

The green LED on the side of the circulator indicates the presence of 230V voltage when it is flashing.

If the LED is off, check the voltage at the output terminals of relay R1 of the controller when it is powered (see figure below).

  • If V = 230V => check the connection of the power cable to the pump, if it is correct then the pump must be replaced.
  • If V = 0 V => Replacement of the regulation is necessary.


b) Checking the PWM signal

The regulation generates a DC voltage of about 10 V when the PWM signal controls the pump.

To verify that the PWM output is functional, the voltage at the PWM terminals of the regulation must be measured when the relay has been set to MAN1 = Max* and one of the 2 cables has been removed from the regulation (see figure below).

  • If V = 10 V => replacement of the pump is necessary.
  • If V = 0 V => replacement of the regulation required.

* NB : To switch to forced operation, use the Mode_manuel_r_gulation_DualSun_SLL.PNG.png  button then validate MAN1, change the value with the knob to the desired value and then validate again with the Touche_valid_.PNG.png button.


(A) = Disconnect this this strand before measurement


2- Replacement of the circulator

The circulator is marked (7) in figure below:



  • Switch off the pump by unplugging the regulator.
  • Disconnect the 2 pump cables (power and PWM).
  • Close the blue ball valve (6) - horizontal
  • Turn the flow meter valve (8) 90° clockwise - horizontal (see figure below).


  • Open the drain valve (9).
  • The heat transfer medium in the pump can now flow out.
  • Unscrew the union nut on the top side of the pump to drain the pump.
  • After this, dismantle the pump and assemble the replacement pump.
  • Reconnect the 2 pump cables.
  • Open the blue ball valve (6) - vertical.
  • Return the flow meter valve (8) to its initial position - vertical, flat at the bottom.
  • Turn on the pump to start it, do not hesitate to make successive start/stop to prime it if it cavitates at start-up.
  • Run the pump in forced operation: MAN1 = Max
  • Adjust the operating flow rate by turning the flow meter valve (8):
  • Operating flow rate = 1 L/min/panel x Number_SPRING_panels
  • Switch the pump to automatic mode: MAN1 = Auto
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