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Plant Engineering Calculator

Updated Sep 18, 2026

Condensate Contamination Loss Calculator — Rejected Return, Heat & Water Cost

Estimate the thermal and water penalty when contaminated condensate must be rejected instead of returned to the boiler house.

Live calculationWorking shownPrivate in browser

Inputs

Results

Sensible heat lost 69.77 kW
Annual heat 418600 kWh
Annual rejected water 6000 m³
Combined value $22744
More actions

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Formula

Q=m·Cp·(Tcond−Tmakeup); annual water=m×hours.

Your calculation, step by step

These steps use the values currently entered above so the result can be checked independently.

  1. 1.Temperature advantage = 90.00 − 30.00 = 60.00 °C.
  2. 2.Sensible heat = 1000.00 kg/h × 4.186 kJ/kg-K × 60.00 K ÷ 3600 = 69.7667 kW.
  3. 3.Annual heat = 69.7667 × 6000 = 418600.0 kWh.
  4. 4.Screening rejected-water volume = 1000.00 × 6000 ÷ 1000 = 6000.00 m³/year (1,000 kg ≈ 1 m³).
  5. 5.Combined entered value = 418600.0 × $0.0400 + 6000.00 × $1.0000 = $22744.00.

How to use this calculator

  1. Enter measured or design values using the units shown beside each field.
  2. Review the live results and the substituted calculation steps before using the estimate.
  3. Check the assumptions below, then continue to a related calculator when the next engineering decision needs another model.

Worked example

Rejecting 1,000 kg/h of 90°C condensate instead of 30°C makeup discards about 69.8 kW of sensible heat.

Assumptions and limits

  • Sensible heat only; flash-steam value is a separate job.
  • Water volume uses the screening approximation 1,000 kg liquid ≈ 1 m³; use actual density for tighter accounting.
  • Only return condensate when chemistry and contamination controls permit it.

How to interpret the result

Treat the primary result as an engineering screening value, then use the secondary outputs to understand scale, energy or operating impact. Confirm site measurements, equipment limits and applicable standards before making a design or control change.

Questions engineers ask

Why is rejected condensate both an energy loss and a water loss?

Hot condensate replaces cold makeup water when it is safely returned. Rejecting it loses its sensible heat and forces the plant to replace roughly the same liquid mass with treated makeup water, with additional water, chemical and often sewer costs.

Does this include flash-steam value from rejected condensate?

No. This owner intentionally calculates sensible liquid heat relative to the entered makeup-water temperature. If the condensate pressure is reduced and flashing occurs, evaluate flash steam and phase-change enthalpy separately.

Can contaminated condensate always be returned after valuing the loss?

No. Chemistry and contamination risk govern return eligibility. The calculation shows the economic/thermal consequence of rejection; it does not override boiler-water quality, process-safety or treatment requirements.

Continue the calculation

Use the next calculator in the same engineering workflow instead of restarting from search.

condensate recovery energy savingscondensate returnboiler makeup water
Methodology. MAXScanner shows the governing formula, entered values and calculation outputs so the estimate is auditable. The calculator is a screening aid; assumptions and equipment-specific limits remain part of the engineering review.