Kelvin

Read the duty ledger: Pass, Undersized, Oversized and Not judged

How the Equipment page judges each pick against its duty, what each status word means, and what the Source column says about a model.

Pipework, equipment and charge · Updated 7 Oct 2026

  1. 1

    Read the Duty ledger at the top of Equipment. Each component has a row: its Duty, what's Selected, the model's Source, its Capacity, Margin and Status, then the Rule it was judged by.

  2. 2

    Choose a component's name to jump to its block below, where the same check is set out in full.

  3. 3

    Where a row reads Not judged, read the reason in its block and enter what it asks for.

Margin is capacity ÷ duty − 1, written as a size and a direction, such as 12% spare or 8% short. The oil separator's margin is its flow as a share of its rating instead, and the liquid line's is the subcooling left, in K.

What the status words mean

  • Pass: within the rule's band. A pass carries no mark.
  • Undersized (critical): below the rule's lower limit.
  • Oversized (warning): above its upper limit.
  • Not judged (note): the model can't be rated at this design's conditions from what was entered, and the reason says why, such as a rating at another TD with no published correction, or another refrigerant with no published factor.
  • A dash: nothing is selected yet.

The rules

  • Evaporators: under 0.9× the load per unit is undersized, over 1.5× oversized. A second check reads Below rack SST when the room temperature less the KTD falls below the rack's SST.
  • Expansion valves: under 0.85× the load per unit is undersized. A TXV over 1.5× reads Floodback risk; any other valve over 1.8× reads Oversized.
  • Compressors: below 0% spare is undersized, over 50% spare oversized.
  • Condenser and gas cooler: under 1.0× the heat rejection, compressor power plus cooling load, is undersized, over 1.5× oversized. The condenser also checks that ambient plus the TD it needs doesn't exceed design condensing (Exceeds design).
  • Oil separator: the flow through each separator against its rated flow. An entered rating reads Optimal within it, Above rated over 100%, and Below minimum flow only if the datasheet publishes a minimum.
  • Receiver or flash tank: its pump-down plus the condenser's, against the estimated system charge. Under 1.0× is undersized, over 2.0× oversized, and No charge estimate where there's nothing to estimate yet.
  • Liquid line: Flash gas risk when the line's saturation drop uses up the available subcooling.

These are the thresholds the page states beside each rule.

The Source column

  • Entered, with the document it came from: typed in for this project.
  • Library, then checked, approved or not checked: copied unchanged from the firm library. An entry not yet checked carries a note mark.
  • Displacement · estimate: a compressor rated by its swept volume.
  • The equipment report lists every model's source again in its Sources section.

What the duties stand on

Under the ledger, Calculated from names the system, the linked pipe layout and the refrigerant the duties come from, and the charge estimate the receiver is judged against. That estimate is worked live from these picks and the layout, not read from a saved charge. Anything missing says what it leaves unjudged.

Note

The ledger and each block below run the same checks, so they can't disagree.