Hi Matthew,
We have a given flow rate for the system and a pressure drop of the indoor unit and outdoor unit. We have a spec to design for a certain length of pipework, but I would assume if the majority (or all) of the pipework was vertical instead of horizontal then it would equate to less than the design length of pipework due to gravity?
Just like accounting for fittings and bends where there is an equivalent length, I just assumed there would be something similar for vertical pipework.