Practically, is there a difference between the cool and dry modes? I've read up on how they work and it seems like dry mode saves more energy. However, I find that my room is cooler on dry mode as compared to when I set to 26C all day long. The dry mode doesn't have a temperature control on the remote. I'm using the Daikin ftks25dvm fan coil.
If the dry mode does indeed cost less than the cool mode at 26C, then I should probably leave in it dry mode 24/7, right?
This simply goes to show that your comfort level is more dependent on humidity than temperature.
Dry mode works similarly to cool mode, except that it lowers the refrigerant flow and reduces the fan speed within the fan coil. The aim now is to extract as much moisture from the air as possible, and not to lower the temperature. To do that, the duration of air flowing over the cooling coil will be increased to improve the moisture extraction.
The compressor will still be used although at a decreased load, as there is not much heat energy transfer.
The point of aircon is to keep you comfortable right? So use whichever mode that makes your feel the best. Unless you have devices/objects in the room which needs temperature or humidity control. Then pick your mode as per required.
That being said, dry mode does indeed consume less electricity per unit time, compared to cool mode. But that doesn't mean you should run it 24/7 either. The compressor needs to rest.