OK, interesting, I think this is the first time I see 24V DC non-latching valves. The user manual seems to refer to both 24V DC and 24V AC coil voltage, I assume this means two different types of solenoid?
Yes you can purchase an ac or dc version of the valve or just exchange the solenoid to change the type. Unfortunately I did not purchase these valves or sprinkler system they came with the property. The old controller is completely dead and more then 30 years old.
Anyways, if you’ve already invested in the DC valves, you can modify the OpenSprinkler circuit by replacing the triacs with transistors like MPSA14. You won’t need the flyback diode any more because all current versions of OpenSprinkler have per-channel transient voltage suppressor (TVS) or MOV (these serve as surge voltage protectors). You can also use a relay board in conjunction with OpenSprinkler, but it will be much more bulky.
I was also taking a look at your blog about the relay board but if I understand correctly I would still have to replace the Triacs anyway, Is this correct?
It is also a little unclear for me how the relay board works as there seems to be more outputs then inputs. The old controller also has some kind of relay board with 8 inputs that control 20 outputs(zones).
Is it not necessary to reprogram the opensprinkler for this case?
Thanks for your help