Variable-speed pump power factor at typical run speedmedium confidence
- Observed range
- 0.1 — 0.3 (typical 0.16)share of full-speed power
- Why this value
- The affinity laws give power proportional to the cube of speed, so a pump at half speed draws one eighth the power. Real installations run between 40% and 60% of full speed depending on plumbing restriction and filter condition, giving 0.06 to 0.22; we selected 0.16 for variable speed and 0.28 for two-speed low. The comparison in the calculator also lengthens variable-speed runtime to deliver equal turnover, so the saving shown is not an artefact of comparing unequal work.
- Applies to
- Not regionally variable.
- Known limits
- No additional limitation recorded.
- Sources
- Recorded before the richer schema; see rationale for provenance
- Last verified
- 2026-07-31 · reviewed biennial