Water heater recovery rate calculator

Estimate gallons per hour of recovery from input, efficiency and temperature rise for gas or electric water heaters.

What this means

Recovery rate is how many gallons per hour a heater can raise by a given temperature rise. A larger rise, such as in winter with colder inlet water, lowers recovery. Compare with the manufacturer's rated recovery.

Formula used

  • GPH = (BTU input × efficiency) ÷ (8.33 × ΔT)
  • Electric: BTU = kW × 3412
  • Metric: L/h = kW × efficiency × 860 ÷ ΔT (K)

Related tools

Gas meter clocking calculator · Pipe volume and fill time calculator · Hydronic GPM, BTU and ΔT calculator

Estimates based on your inputs. Always verify against the manufacturer's data and the codes that apply where you work.

Stuck on a fault? Ask Brixon, first question free

Describe the symptom and your readings. Brixon helps you work through the free, quick checks first, then the deeper tests. It can be wrong, so confirm on the equipment.

Ask Brixon, first question free