Matjaz

Good luck to all selfbuilders, hope you will make even better controller... for those who want help Im available always by personal message.

heat pump flows so much energy in the system, as much as it needed at the moment like INVERTER If you would read the pdf manual you would understand, in he beggining we thought same as you..

You are correct. Heat pump changes the steps according to flow temperature sensor... You set lets say 45 degrees and it will always keep it , no matter of other conditions.. triggers OFF by room thermostat

if you use steps from 1-7 you will have significally lower energy consumption and smaller number of on/off of compressor.. What this means for years of use we all know.. [price for product removed, - please read the forum terms and conditions: https://forum.buildhub.org.uk/terms/ ]

with this "controller above" definitely no as I said it works on 100% power of compressor and has no controll for flow temperature and so on... But as I mentioned before it is possible to find controller for AX-09 IVT with functions on popular sites..

This "controller" version is very dangerous for heat pump. It works on 100% or on 0% That Siemens thermostat trigger off/on the heatpump when desired temperature is reached. So basically it is ON/OFF heat pump, controllers for IVT AX-09 can be found on popular sites...