Understood, ok i'm discarding PWM for AC Solenoids 
Another question: if i send power with less frequency? If i power on the triac in a way to get a 45hz instead of 60hz, the ac solenoid will open slowly right? And if i send power with really lower frequency, it will close slowly? In this way may i be able to control how much open the internal valve?
Using the circuit posted above, if i send the power with a frequency that oscillate between 15hz and 45hz, should it open slowly and close slowly, right? Because i'm not cutting off the power to the inductive load, i'm just giving it less power.
Is this right?
Thank you!