Thanks for the replies.

The rate of ON/OFF is to be determined. I need at least 10 steps from stop to full speed.

I am setting up a test circuit to see how it goes. With TRIACS like BTA12/600BW the snubber is not necessary (these are characterized as snubberless).

As for the heat I feel that it is not going to build up since the motor is running with almost normal voltage and is gettin power at zero crossing.

Ioannis