A header sized so that the pressure gradient along its length stays small compared with the branch resistance — which is what keeps the node at the top of the rack from running warmer than the node at the bottom. Standard configuration is reverse-return; direct-return is available where the rack layout demands it.
Ports are dry-break QD-16 on 42 mm centres as standard, with blanking plugs on unused positions so a partially populated rack can be commissioned and filled exactly like a full one.
