First, already have 4 valve actuators running on this system.
While doing final walk through with PB we found out our spa return pipe does not have a check valve installed. As a result of this the water drains from the spa whenever the filter is off or the system is in spa only mode. This actually went unnoticed for many weeks since the spa return valve had been closed while the spillover brickwork was sealed. When the valve was finally open our pool had been on for 24/7 for some time after that so return was always sending water in. Only recently did we switch to timed filter runs. It seems we have several options. Since we have limited space at the existing valve, simply replace it with a check valve. But then I've eliminated the ability to turn the return off at all. Other option would be to replace the existing manual valve with a 5th actuated valve, however the PS-8 has connection for 4 actuators. Is it possible to join to valves off of one connection? That way, when everything is switched to spa mode, the valve on the return could be closed (since it's not needed while in dedicated spa mode). Right now, in order to use the spa, I have to manually close the return valve to prevent water from backflowing through this piping. One other option is to dig underneath footer where equipment is and install a check valve underground.
Sorry for the long explanation. Bottom line is I would like to consider my options and the actuator may be less expensive than having them dig and add check valve. If it's possible to join this actuator with the spa valve actuator, that would be my preference. still can close the return if needed and no more draining. Probably could have been avoided if they had installed in first place or at least if I had enough room to add the check valve without digging.