Thanks for the reply. I have the unit back on the bench and now I’m really confused.
I connected a second Pi to help eliminate the Pi as the problem.
After a fresh start from power off I measure voltage between each zone and common I received something around 4vac. Is this expected?
I then run ospi_selftest. Sometimes one of the zones will measure 24vac when activated but there doesn’t appear to be a pattern. Furthermore, in any one run of self_test usually only 1 zone appears to operate normally (though sometimes 2) and it doesn’t tend to be the same zone.
Thanks for the help,
EDIT 1: I just reconnected the original Pi and after 5 runs of self_test I didn’t measure 24vac on any of the zones.
EDIT 2: Hum, and now it seems to be working as expected with the 2nd Pi. I’ll continue testing on the bench, then attach the extension, and then reattach to actual valves.
EDIT 3: The extension is now working properly on the bench as well. I still measure ~4vac on closed zones, is that correct?