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Water Heater Recovery Rate Calculator

Gallons per hour a water heater can warm by ΔT.

Compute the recovery rate (gallons per hour) of a gas water heater from its BTU input rating, its efficiency, and the desired temperature rise: GPH = BTU · efficiency / (8.33 · ΔT).

Marcus Laurent By Marcus Laurent
Published Last reviewed 1 min read

Inputs

BTU/h
%
°F

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

GPH = BTU · η / (8.33 · ΔT °F)

In depth

Compute the recovery rate (gallons per hour) of a gas water heater from its BTU input rating, its efficiency, and the desired temperature rise: GPH = BTU · efficiency / (8.33 · ΔT).