Two underfloor heating manifolds

Hi,

I needed to have two underfloor heating maifolds due to space constraints for the same floor (ground floor) and one will be physically monted above the other on the wall and they are both the same sze with three circuits each. Can they just be connected in parallel with one another or should I install a low loss header? Both manifolds have roughly equal pipe runs (therefore also similar pressure loss and dT).

I am hoping no low loss header is needed and I am able to balance each run without too much pain.

Low loss headers are used when adding addational pumps to a system, so will not be required unless you need a dedicated pump for UFH.