My parents used to sell swimming pools and I used to go out and plumb the pool houses.
These actuators have 3 input wires:
- position / live 1 (red)
- position / live 2 (white)
- Neutral (black)
You have correctly selected SPDT relays but in your schematic you are only using them as SPST?
Assuming the orange wires going to the actuators in your schematic are the live wires, you have not shown any neutral connection and therefore the actuators will not complete a circuit (won’t work).
You should have the live wire from the 24v supply going to the common terminal on each of the SPDT relays. Neutral (black) from the 24v supply should go straight to each actuator.
Red and white wires from the actuators should go to the NO and NC terminals of each relay. (Doesn’t matter which way around, can be reversed later using the toggle switch on the actuator itself)
If I was doing this project I would use standard 110v zwave relays and wire them to toggle 110v coil (dumb) SPDT relays. I would then wire the dry contact side of each relay to the actuators, as noted above.
By using zwave relays you can also rig push buttons into a control panel rather than having to use your phone and / or toggle switch on the sides of the actuators (only intended for maintenance).
Use of Arduino and the relay board you linked to above would also work, but IMHO it just adds too much complication and makes it harder to have the manual switching.
Something very important that you need to watch out for is that you don’t want to be pulling water from the spa and dumping it into the pool… as the spa will quickly drain, pipes would run dry and the water cooled pump would burn out (the heater will protect itself via flow sensors, the pump won’t)
I suggest you use 1nr DPDT relay to control both the out actuator (after the heater) and the actuator that switches suction between pool and spa (before the pump) together. That way you can only pull and return to the same location (pool or spa), these two valves will therefore be hard wired to turn together and won’t be independently controllable, which is what you want.
Summary, you need:
- 2nr SPDT dumb relays
- 1nr DPDT dumb relay
- 3nr zwave dry contact relays
- 3nr push to make momentary switches (optional manual control)
- A large watertight junction box for all electrics (if mounting in the pool house?). Manual switches can be mounted through this junction box to create a control panel if you select the correct type of switches (ones that poke through a hole with gaskets)
You also need a good (working) schematic!
Hope this helps?