John,
I do not see a make-up line that makes your spa spillover.. What they have done is make the Return valve only rotate 90 degrees, which is stupid since you have an EasyTouch...
I still am not sure why the spa only drains when left in the spa mode. Just to make sure I am looking at this correctly, please put the system in the Spa mode and let me know where the handle of both the Intake and Return valves are pointed.. The Intake valve is right in front of the pump and the Return valve is down by you filter..
Have you ever taken out the check valve at the top of your plumbing just to the right of the Tab feeder and inspected it??
If your Intake valve was set correctly, your pool would operate like this..
Pool mode... All the water would be sucked from only the Pool through Intake valve by the pump and then pushed through the filter and heater and then through the Return valve and back to only the pool. No spa spillover
Spa mode... All the water would be sucked from only the Spa through Intake valve by the pump and then pushed through the filter and heater and then through the Return valve and back to only the Spa. No spa spillover
Spillover mode... All the water would be sucked from only the
Pool through Intake valve by the pump and then pushed through the filter and heater and then through the Return valve and back to only the
Spa. Huge spillover that you control via pump speed.. A trickle or Niagara falls, whatever works for you.
Thanks,
Jim R.