Hot Water System Running Cost Comparison Calculator - Australian Energy Foundation
Hot Water System Running Cost Comparison Calculator

Hot Water System Running Cost Comparison Calculator

Use this tool to estimate your annual running costs for different types of water heaters to see if you would benefit by getting a different kind of water heater. Only input the information you know or have, for other boxes, leave the default value input. If you need assistance with filling this calculator out and how to read the results, please call our advisors on 1300 23 68 55 with your electricity and/or gas bills on hand.

Please read the Notes & Assumptions at the bottom of the page when calculating your hot water running costs.

Notes and Assumptions

  • Hot water consumption is estimated only for showers. Other uses are normally relatively small, e.g. hand-washing dishes. Most modern washing machines and dishwashers take cold water and heat it internally.
  • This calculator provides only a rough estimate – hot water consumption and cost is affected by several site-specific factors. For more information please contact our energy advisors on 1300 23 68 55.
  • Controlled Load circuits are generally only used for standard electric hot water, not for heat pumps. Electricity can only flow in these circuits at certain times of day, e.g. overnight.
  • Heat pump hot water systems are often run at night using a timer, on a standard electrical circuit. This can be a good option if your electricity plan gives a cheaper rate overnight.
  • Instantaneous or “continuous” electric water heaters have no tank.  During a shower they consume a lot of power – too much to be covered by a typical solar system. Other electric options heat up a tank at a lower power level over a longer time, more suitable to be covered by solar power.
  • Solar calculations assume a typical size solar system and typical household electricity usage patterns. A home with solar panels is assumed to run a heat pump or standard electric water heater on a timer around midday.  Some grid power will still be consumed in addition to solar power during cloudy periods. This is minimised with a heat pump because it runs at lower power.
  • It’s possible to automatically switch off a water heater during cloudy periods, or reduce its power level. Several devices are available to achieve this, but they’re not included in this calculator.
  • Feed-in tariffs tend to be updated each year, varying with the wholesale market value of electricity.  In most parts of Australia 6c is a reasonable average for feed-in tariffs over an appliance lifespan.
  • If your electricity plan uses complicated rates (e.g. varying by season) you’ll need to estimate an average value for this calculator.
  • Bills include a fixed daily supply charge as well as energy charges.  If selecting an electric water heater will eliminate your gas bill, you should allow for this saving over an appliance lifespan.  E.g. $1 per day over 10 years = $3,650 saved.
  • Another type of water heater uses 1-3 rooftop panels to directly heat water using the sun’s heat. These aren’t included in this calculator due to the variety of such systems. In most climates they also require a gas or electric booster to cover cloudy periods. As a rule of thumb, a good electrically-boosted solar thermal hot water system would consume about as much annual electricity as a heat pump. Most of its electricity will be used during cloudy times, so it won’t be helped much by solar electricity.
  • The household is assumed to be connected to the electricity grid. It’s also possible to heat water with firewood, e.g. a wetback on a wood heater. This calculator doesn’t include such options.