Hi Rony,
this depends on your installation.
1. DC is made for smaller installations and so it includes a power supply. You can run up to 3 valves simultaneously.
2. AC is for larger, scalable installations. So you need to buy a powersupply that fits your needs and then you can run as many valves that your powersupply can handle simultaneously.
3. With AC you can also controll 24VAC relay, but not with DC.
simultaneously means “at the same time”. You can run up to 72 valves in sequence with both devices.
We are on vacation from June 20th. until June 28th - from June 29th we are here for you again. Order by June 19th. will still be sent if in stock.