- 1
In the Segment ledger, tick Riser under the line of each suction run that rises. The plan is drawn flat, so this is how Kelvin knows.
- 2
Type how far it rises, in metres, in the cell that appears under it. Left blank, the whole run is taken to rise.
- 3
Under Velocity bands and ΔK limits, enter Riser min for suction: the minimum velocity your own standard calls for to carry oil up. There's no default, and a blank leaves risers not judged.
- 4
Under Pipe sizing, set Riser check load to the share of design load the riser must still carry oil at, such as with cases in defrost or compressors unloaded. Blank checks it at the full design load.
What Kelvin does with it
- An auto-sized riser that's too slow at the check load is taken down to the largest tube that reaches the minimum without going over the band's maximum at design load.
- If only part of the run rises, the horizontal keeps the size its pressure drop calls for, and only the rise takes the smaller bore. The ledger shows the riser's size and metres under Size, and the plan labels the run S, R and L.
- The run's pressure drop is both lengths added, and the refrigerant charge counts each bore's own metres.
- On Max ΔK or Both, the paths through a riser that was taken down are held again around it, by raising other segments, never the rise itself.
What the check says
- Pass: the riser's velocity at the check load reaches the minimum.
- Double riser needed (critical): no single standard tube reaches the minimum and stays within the band's maximum at design load.
- Riser velocity low (critical): a size you entered is too slow at the check load. Kelvin never changes an entered size.
- Riser not judged: no riser minimum is entered for that line.
Note
Discharge lines can be ticked as risers too, under System lines, and are judged against the discharge Riser min. A liquid riser has no oil-return check.