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5.2 E) PROTECTION FROM OVERHEATING
Also the operation with very hot water causes cavitation risks and wears the seals, so it
must be avoided.
Reduction of the motor R.P.M.
Especially if the pump is driven by an electric motor driven by an inverter, it is neces-
sary to install a device able to reduce the engine/motor R.P.M. and consequently the
pump capacity, when the bypass valve is operating. With this device the water tem-
perature is reduced.
A thermostat installed inside the tank indicating the achievement of too high tem-
peratures or, when possible, stopping the motor, is another recommended safety
system.
5.2 F) PROTECTION FROM POOR OR NON SUPPLY.
The pump does not have to run dry to avoid the wear of the seals and the overheating caus-
ing the pistons failure, irreparably damaging the pump.
A level switch indicating lack of water in the reservoir, or, when possible, stopping the en-
gine/motor is a recommended way to prevent the dry operation.
Next to the inlet pipe a Pressure switch must be installed, provided with an alarm signal, or
if possible able to stop the engine/motor when the inlet pressure decreases under the value
of incipient cavitation.
In case the level switch, the thermostat or the pressure switch cause the en-
gine/motor stop, the switch to be used must be with manual starting, to avoid the
spontaneous re-starting of the engine/motor.
5.2 G) ENERGY SAVING / PUMP CORRECT USE
It is quite normal that the pump flow is oversized in comparison with the real use needs.
For a correct running of the system, the water circulated through the regulating valve does
not have to exceed 10-15% of the pump flow.
Otherwise, besides the useless energy waste, a water overheating will be generated in the
supply tank, increasing the cavitation risks. Moreover, all the circuit parts, and in particular
the regulating valves, are subject to a continuous and extreme stress.
It is therefore recommended to adapt the pump capacity to the actual system needs, reduc-
ing the pump R.P.M.
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