Grundfos ALPHA1 L Instrucciones De Instalación Y Funcionamiento página 13

7.4.6 Pump setting for domestic hot-water systems
Recommended and alternative pump settings:
System type
Recommended
Constant curve or
Domestic constant speed, I, II or
hot-water III. See section
system 7.4.4 Constant curve or
constant speed, I, II or III
See also section 10.2 Guide to performance
Factory setting: Radiator heating mode. See section
7.4.1 Radiator heating mode.
7.4.7 Changing from recommended to alternative pump
setting
Heating systems are relatively slow systems that cannot be set to
the optimum operation within minutes or hours.
If the recommended pump setting does not give the desired
distribution of heat in the rooms of the house, change the pump
setting to the shown alternative.
7.4.8 Externally controlled signal connection: PWM input
signal profile A (heating)
The ALPHA1 L can be controlled via a digital low-voltage
pulse-width modulation (PWM) signal.
The circulator runs on constant speed curves depending on the
PWM input signal. The speed decreases when the PWM value
increases. If PWM equals 0, the circulator runs at maximum
speed.
Max.
Max.
PWM input signal
PWM input signal [%]
Fig. 15 PWM input signal profile A (heating)
PWM input signal [%] Pump status
≤ 10 Maximum speed: max.
> 10 / ≤ 84 Variable speed: min. to max.
> 84 / ≤ 91 Minimum speed: IN
> 91/95 Hysteresis area: on/off
> 95 / ≤ 100 Standby mode: off
At high PWM signal percentages (duty cycles), a hysteresis
prevents the circulator from starting and stopping if the input
signal fluctuates around the shifting point.
At low PWM signal percentages, the circulator speed is high for
safety reasons. In case of a cable breakage in a gas boiler
system, the circulators will continue to run at maximum speed to
transfer heat from the primary heat exchanger. This is also
suitable for heat circulators to ensure that the circulators transfer
heat in case of a cable breakage.
Pump setting
Alternative
No alternatives
curves.
7.4.9 Setting up the PWM input signal
To enable the external control mode (PWM profile A), you need a
signal cable connected to an external system. The cable can be
supplied with the circulator as an accessory. See section
11. Accessories,
The cable connection has three conductors: signal input, signal
output and signal reference.
The cable must be connected to the control box via a
mini superseal plug. See fig. 16.
Fig. 16 Mini superseal plug
To set the signal connection, do as follows:
1. Make sure that the pump is turned off.
2. The PWM signal connection is covered by a blind plug.
Remove the plug.
3. Connect the signal cable with the mini superseal plug.
4. Turn on the power supply.
5. The pump automatically detects the PWM input signal and
enables the control mode on the pump.
See fig. 17.
1 x 230 V + 10 / -15%
∽ 50/60 Hz
Fig. 17 Connecting the signal cable to the ALPHA1 L
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