The heat-rejection load table still prints 385 kW in its conservative column after the hydraulic chapter computed a later figure of 105 kW and forbade anyone from deducting the difference on its own. Pump work enters the fluid, so the duty the distribution units must reject is the liquid-side computing heat plus the share of secondary pump power that becomes heat in the loop. The hydraulic basis carries that share at 1.00, the value for a canned or wet-rotor machine, where a dry motor and coupling would give 0.85 to 0.90 [SENSITIVITY]. It carries the pump power itself at the electrical side's allowance of 385 kW [TARGET]. That the shortfall this produces against an eleven-unit branch is the pump term exactly, and that the allowance belongs to a temperature difference the same basis rejects, are both already on the record and are taken here as stated. What has not been done is to run the chapter's own corrected pump figure back through its own identity.
Substitution Moves Two Published Figures, Not the Failure
Doing that moves two published numbers and leaves the conclusion where it was. Substituting the upper of the chapter's two later pump figures into the duty identity leaves a deficit of 105 kW instead of 385 kW, about 0.9 per cent instead of 3.2 [MODELED]. The branch still fails to close at full liquid fraction. It fails by roughly a quarter of the amount the duty table implies, which is a different statement about the same failure and a weaker one.
The concurrent-maintain short on the eleven-unit grouping does not move when the pump kilowatts move. That hole is a grouping arithmetic, not a pump-heat arithmetic.
The flow table the enquiry package draws on is built on duty figures with the larger pump term inside them. At the recommended temperature difference the published whole-site flow is 1,069 cubic metres an hour; recomputing the same identity with the corrected pump term gives about 1,044, some 2.4 per cent lower [MODELED]. The chapter is deliberately conservative here and says so, on the ground that primary-side fans, primary circulation and make-up treatment may be absent from the same allowance and would consume anything released.
The same additive term also sets where the branch stops closing. Working the identity the other way, the duty crosses the eleven-unit branch's redundant capacity at a liquid fraction of about 0.97, which is the figure the chapter prints as the failure threshold [MODELED]. With the corrected pump power the crossing moves close to 0.99. Neither is a comfortable place for a threshold to sit, because the chapter's own upper bound on liquid fraction is 0.97 and the residual air-side share it assumes is three to eight per cent.
Those two figures are the ones that leave the chapter. The flow is what a pipe schedule and an enquiry package are sized against, and the crossing is what a control strategy is written to keep clear of; the deficit itself and the allowance behind it stay inside the calculation and do not travel in the same way. A 2.4 per cent move on a flow, and two hundredths on a liquid fraction, are small in isolation and are not small in figures that other documents copy without recomputing them.
The Conservative Column Still Carries 385 kW
The heat-rejection chapter verified the ban on a lone deduction. Its baseline column takes 105 kW. Its conservative column keeps 385 kW. The interval between them is the hydraulic chapter's own range, and the conservative end is the electrical already-used value, not a hydraulic result. An independent check of a different supplier packet computed secondary pump heat near 12 kW on that packet's own assumed efficiencies. That figure is not this loop and is not a replacement for either column.
The Corrected Pump Figure May Not Be Deducted Alone
The hydraulic chapter does not correct the electrical allowance and forbids anyone downstream from correcting it. It registers the difference as a change candidate and marks the pump figure as a mandatory check when the primary side closes, so that three movements in opposite directions are settled in one netting rather than one at a time. Neither recomputed figure above may therefore be lifted out on its own; both exist as a sensitivity on a number the document is still carrying.
The 1.00 Conversion Fraction Is Not a Plant Property
Whether the conversion fraction is right depends on a purchase nobody has made. No pump has been selected, so the construction of the machines is unknown, and the 0.85 to 0.90 band would take roughly 40 to 58 kW back out of the duty at the electrical side's figure alone. The 385 kW is itself an assumed allowance awaiting supplier data, recorded as such in the same row that admits it into the protected-load total.
Limits and open items
Confirmed: the hydraulic chapter forbids deducting the corrected pump figure from protected load on its own; the heat-rejection table keeps 385 kW in the conservative column. [FACT]
Carried allowance: 385 kW, graded as an electrical-side assumption. [TARGET]
Conversion fraction: 1.00 against a dry-motor band of 0.85 to 0.90. [SENSITIVITY]
Substitution results, not a release: a deficit of 105 kW instead of 385 kW, about 0.9 per cent instead of 3.2; a crossing near 0.99 instead of 0.97; whole-site flow about 1,044 cubic metres an hour against a published 1,069. [MODELED]
Open: secondary pump power at the duty point of an actual machine; the three movements the chapter wants settled in one netting. [HOLD]
Nothing here has been reviewed or sealed by an Engineer of Record. Nothing describes how any installed system behaved.
Secondary Pump Power at the Duty Point Is Unmeasured
What would move the identity is the one measurement nobody has: secondary pump power at the duty point of an actual machine. No pump has been chosen to measure it on, and the three movements the chapter wants settled in one netting are all still open, so the term that decides whether an eleven-unit branch closes stays at a value the same document argues is four to eight times too large.
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Source: K&K Data Service Inc., “Correcting CDU Pump Heat Moves the Close Threshold, Not the Failure,” https://www.kkdatasvc.com/lab/hydraulic-calculation-detail/a-corrected-pump-term-moves-the-failure-threshold-not-the-failure/.
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