I am terribly out of project schedule. New boiller regulation valve not meet expectations on tests. Basically it is working and it is usably but looks strange.

Whole regulation range is round zero valve adjustment and it is very sensitive for boiller (first) pump power. Something what looks clear and flat become more complex. ( As usually... )

Looks like nobody knows how it is working include me! Hydrodynamic as well as aerodynamic rools are out of human senses. On internet and at pratice what a saw regulation configuration all the same. Two pumps and four way valve between. It is what I built up now. Of course there is stupid idea too tu use one pump only. It leave boiler in bad environment and health conditions - low end boiller is at very low temperature.

I have to go my own way to do it. This weekend I will start from zero and will rebuilt pipes and valves again! Second problem to solve are shame air bubles in system because I did not take care about it and wrong air release valve to replace.