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Water heater cost comparison

Rank storage, instantaneous and heat-pump water-heater options by annual energy cost, using the same hot-water demand and your efficiency, standby-loss and tariff assumptions.

Up to 30 uniquely named options and 100,000 characters. Daily volume 0 to 10 million L in L, US gal or Imp gal; temperature rise 0 to 100 K in K, °C or °F; 1 to 366 whole days. Storage/instantaneous efficiency above 0 to 1, heat-pump COP above 0 to 20, standby 0 to 100,000 input kWh/day and prices 0 to 100,000 per input kWh. Calculated on your device. Downloads: JSON report, results CSV and ranked option CSV. One option per line: name, type, fuel, efficiency or COP, standby input kWh/day and price per input kWh. Up to 100,000 characters. Review the settings before running.

Your result

How to use Water heater cost comparison
  1. Enter daily hot-water volume, temperature rise and days of use.
  2. Enter one option per line: name, Storage/Instantaneous/Heat pump, fuel, efficiency fraction or COP, standby input kWh/day and price per input kWh.
  3. Check that standby is not already included in the efficiency figure you entered.
  4. Review annual energy, cost and ranking, then download the JSON report and comparison CSV.

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Equal water demand

Useful heat is litres × 4.186 × temperature rise in K / 3600 for each day. Water density is approximated as 1 kg/L and specific heat as 4.186 kJ/(kg K). Daily volume and temperature rise are the same for every option.

Efficiency and standby

For storage or instantaneous heaters, enter efficiency as a fraction, such as 0.9 for 90%. For a heat pump enter COP, such as 3. Standby is purchased input energy in kWh/day, added after useful heat is divided by efficiency or COP. Enter 0 if it is already included in your performance figure.

A cost comparison

Fuel and heater labels do not assign performance. Options are ranked by annual energy cost rounded to two decimals, with ties retaining input order. Installation, maintenance, standing charges, delivery speed and capacity are outside this estimate.