Thermasol PowerPak 240V wiring diagram shows only two wires for the solenoid (both orange). The two red wires are the float switch. There would not be any voltage on the red ones because their function is just to connect to one another once the water level in the tank rises and the ball floats up to a preset position.
It is just my conjecture at this point but I think the aroma unit would have to measure the voltage or the current on the orange wires to "know" if the valve is open or closed. It would have nothing to do with the float switch, so you can safely disregard the red wires.
Since that is a high voltage solenoid, I don't feel comfortable just saying: "connect to orange wires" because I don't know this aroma unit and you can burn either the aroma unit or the Thermasol power supply (or both) if you hook up a unit that's supposed to measure current in parallel instead of in series. Conversely, if it's supposed to measure voltage instead, if you wire it in series with the solenoid, it will just disable the solenoid.
Alternatively, if the aroma unit is entirely a low voltage device, it can have a current sensing transformer that just clamps onto the solenoid wires (the orange, high voltage ones) and no electrical connection is needed and would indeed be dangerous to make one.
So, as you can see, a lot depends on having more information about that aroma unit and I was not able to find any information about the device whatsoever. Since you possess the aroma unit manual, may I suggest that you post it here as an image attachment which our answering system supports (jpg, png, gif)? This way I can take a look and make a better informed suggestion. Â Â Â