[g.l.amour]

from xperience

if u use a relatively underpowered pump considering the workload, it is better to run in serial . if u run parallel u risk the pump not having enough power to prime both radiators (the air bubbles just keep dancing in the lines, instead of being blown into the airtrap).

in theory the parallel setup is the more efficient one, but can also mean that u have to undergo alot more trouble routing your tubing.

in my setup the difference of temps between serial and parallel was smaller than my measurment fault tolerance.

hope this helps