Very nicely explained, thanks. If the UFH 2 port valve was open and the UFH pump was running, would that not draw flow through from the boiler even if the main pump wasn't on?
Umm its a new installation the diy approach is sometimes to forget about professional design and installation.But. Please post photos of the new manifold arrangement,showing the settings on the mixing valve and the electric control panel. A cad design is necessary for the diy to follow,it explains how to set various items on the manifold and it helps to have this info when selling the property, Wet ufh is an excellent heat idea,done a few. is it diy ? is another question.