These dots represent the load on the system. One dot means the temperature control is working minimally. Four dots means the temperature control system is working as hard as it can.
The system is designed to circulate the water continuously, but the cooling and heating ramps up or down as it is working to reach or maintain the set point. While maintaining the set point, there will likely be only 1 or 2 dots.
Like anything else electronic, it's best if the system isn't constantly overworking itself. Keeping plenty of ventilation around the unit will minimize the load on it.
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