It costs a little more but reduce the number of circs on the trucks. 0 ?? ?? hr Posts: 6,106Member April 2005 Steve, slowing the flowthrough a radiant circuit or HW baseboard, air coil, etc will slow the heat transfer not increase it.There is a limit to how fast of course, velocity and noise are a couple factors.it is not about how long the fluid lingers" in the pipes or the emitters, but the aver