Let me start by saying that I'm posting this in Boffin's Corner because it's about an experiment that curiosity has driven me to try out. But it's probably not something the professional plumbers around here would endorse. Nevertheless, this is what I'm trying:   The issue I'm addressing is running a small, single zone UFH loop using a 30kW system boiler that only has a 3:1 modulation capability. The UFH loop only requires around 2 kW so, in the absence of any other loads, the boiler i