With so much talk about OT and boiler condensing in other threads, I shifted my attention to the little spoken about 'guy', the Automatic Bypass Valve.

In today's world of self modulating pumps, TRVs and zones, how does one set up the ABV?

This is likely to become a topic as debated as "is balancing really relevant with TRVs and zones".

Most boilers will specify a minimum flow rate. So how does one actually measure the flow rate running through the boiler.