When you look up the Cv of a three port TMV, is the pressure drop and flow based on flow from one inlet to the outlet or both inlets to the outlet, or does it not really matter. I am thinking about the circuit where a TMV is used for boiler protection - the biggest pressure drop is likely to be across the TMV, but I can't get my head around if it makes a difference if one or both ports are open?
Also, we use metrics in NZ but most Cv's I have seen are based on imperial measures - are there conversion factors to convert Cv's or do you just have to develop your own?
what comes out of the mixed port is the blend of the H &C port. If it needs more hot, that port opens as the cold closes down. The wax cartridge inside move the spool up and down to vary then opening into the valve from the H & C