Oh well done, @Michal_S, that’s quite a breakthrough.
But please tell us the details of how you did it. Given that neither the remote controller or SNET-Pro2 allow us to enter #2012 values below 10degC, I assume that you forced the 0degC value in either using Modbus (maybe using your MIM-B19N) or with @toadhall’s code (as he describes in Contribution: Samsung ASHP NASA link <-> MQTT bridge (Home Assistant) post #118 onwards). I ask because those of us too mean to invest in a MIM-B19N or HA may want to emulate your success using Python or similar.
Any guidance appreciated!
PS @Topaz’s idea above for fooling the controller into thinking that there’s no DHW circuit looks very interesting as an option to avoid frost protection heat loss from the tank. Have you tried it?