Formula & worked example
B=S·Cf/(Cb−Cf); makeup≈S+B.
For 10 t/h steam, 200 ppm feedwater and 3,000 ppm boiler-water limit, blowdown is about 0.714 t/h.
HVAC engineering calculator · Updated Sep 17, 2026
Boiler Blowdown Calculator — Blowdown Rate, Makeup & Heat Loss
Estimate continuous boiler blowdown from feedwater and boiler-water TDS limits, plus makeup requirement and approximate sensible heat carried by blowdown.
Inputs
Live result
Continuous blowdown 0.71428571 t/h
Blowdown as % of steam 7.1428571%
Nominal makeup 10.714286 t/h
Approx. sensible blowdown heat 62.291667 kW
Assumptions & limits
- Simple steady-state solids balance with negligible solids in steam.
- Chemical treatment and local boiler guidance govern actual TDS limits.
Frequently asked questions
What does this Boiler Blowdown Calculator calculate?
Estimate continuous boiler blowdown from feedwater and boiler-water TDS limits, plus makeup requirement and approximate sensible heat carried by blowdown.
Is this suitable for final equipment selection?
Use it as an auditable engineering cross-check. Final selections should use measured design conditions, manufacturer data, applicable standards and local code.
Why does MAXScanner expose the assumptions?
HVAC shortcuts can hide density, pressure, concentration and effectiveness assumptions. Exposing them makes the result easier to verify and revise.