Verify the inputs
Measure or document each input. If a value is only an estimate, record its source and test a conservative alternative.
Independent energy/ CALCULATOR
Hot-water recirculation energy and cost
Estimate annual pump electricity and the energy needed to replace heat lost from a hot recirculation loop.
FROM ESTIMATE TO ACTION
Use the result, not just the number.
Keep the calculation traceable
Save the input link or copied result together with the date, units and assumptions. A number without its inputs cannot be checked later.
Confirm the decision
Compare the estimate with the related guide, current product data and requirements that apply at your location before buying or building.
Inputs to verify
- Recirculation pump input power (W)
- Use measured electrical input or the pump nameplate input, not hydraulic output.
- Pump run time per day (min/day)
- Use controller history or measured average daily run time.
- Hot supply and return length (m)
- Add the heated supply and return sections of the recirculation loop.
- Average linear pipe heat loss (W/m)
- Use a design or measured value for the actual pipe size, insulation, water and ambient temperatures.
- Hours the loop stays hot per day (h/day)
- Include the cooling period after the pump stops, not only pump motor run time.
- Water-heating efficiency (%)
- Useful heat restored to the loop divided by purchased heater energy.
- Operating days per year (days/year)
- Use the number of days the recirculation system is enabled.
- Energy price (currency units/kWh)
- Use the relevant electricity or delivered-energy price.