Swegon BlueBox Zeta Rev Series Installation, Use And Maintenance Manual page 67

Letter "L" appears in the first screen of the Flowzer menu to indicate that the value ΔPex is lower than the setpoint stored
in parameter "PA22".
If the value ΔPex is higher than the setpoint stored in parameter "PA55", letter "H" appears in this position, instead of "L".
7.3.5.4 Checking the minimum flow rate
Progressively close all the user points and check that the pump speed slows progressively.
If the pump speed fails to be reduced, the reason could be an excessive number of 3-way valves (for example, "Un"-type
user points shown in the reference hydraulic circuit).
In this case, you can check with the installer/design engineer whether it is possible to progressively choke the third port of
the 3-way valve (bypass port) to obtain a progressive reduction in pump speed and consequent increase in total efficiency
of the variable flow rate system.
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We reserve the right to make changes without any prior notice. Translation from original instructions