Thank you for the answer, that's interesting. This means you need cooling demand to obtain heat from the condenser, isn't it?

Therefore if it's cold and I don't need any cooling, I can't get DHW or heating.

Did I misunderstand it?

@Gio - yes. You might want to look at the WaterHeater:HeatPump objects.

@Gio You are correct, you would need cooling demand in the zones in order to have the refrigerant loop reject heat from the condenser to the hot water loop. When it's cold and zones have heating demand instead, the refrigerant loop will need to siphon heat from the condenser instead.

As @kwalkerman mentioned, you could use a WaterHeater:HeatPump object so that DHW system could receive heating year-round. However, this object doesn't provide space heating.

@kwalkerman I think you can provide heating with it, but through a water coil terminal (fan coil for example). In this case I need a direct expasion to provide heating and cooling and a condenser for DHW. During winter (heating demand) I temporarly switch the power to the DHW generation; during summer instead, it reverses the cycle to shortly produce the hot water.

@Aaron Boranian I think I could model both of them, 1 heat pump for DHW and 1 VRF for heating and cooling (basically it's one machine with 2 different operations thus different performances), but they shouldn't never operate together. Could it work? Can I set them not to operate simultaneously with DHW priority?