• Client Services: 08 9240 4018

Hot Water Systems

Hot Water Systems

How to choose the best

We know hot water systems

Choose a hot water system suitable for your household

Don’t wait until your hot water system dies, plan your next purchase now!
Water heating accounts for 25% of your household’s energy use – and it could be even more. It’s worth reviewing your hot water usage well before your system dies and checking out the alternatives. You may find a hot water system that saves you energy and money as well as being kinder to the environment.

Also, a new electric storage system may not be an option for your home because of new regulations aimed at reducing energy consumption.

Which hot water system is best for me?

One person uses on average about 50L of hot water a day. You will use more hot water if you use your dishwasher often, take very long hot showers or often wash clothes in warm or hot water.

Your Know Hot Water Specialist can analyse your home and usage and recommend the best hot water systems for you.

To determine the right size of system, we will need to know:

  • How many people live in your home?
  • How much hot water you use, and when you use it?
  • When do you all shower – in the morning or evening?
  • How do you wash clothes – in hot or cold water?

For most households, a solar HWS can be the most efficient and cheapest to run. If that’s not an option, here are other suggestions:

  • Small household (1-2 people): Instantaneous hot water system (gas or electric) or small gas storage hot water system.
  • Medium household (3-4): Gas hot water system (instantaneous or storage).
  • Large household (5+): Multiple instantaneous hot water systems may be an option but gas storage units may be more economical.

Energy Star rating

Gas hot water systems have energy efficiency star rating labels; the more stars, the more efficient the water heater. The highest rating is six stars. Minimum Energy Performance Standards (MEPS) currently apply for electric hot water storage systems.

Electric or gas hot water system?

When choosing a hot water system, the first decision you’ll need to make is the heating method: electric hot water system, gas hot water system or solar hot water system?

Electric Hot Water Systems

  • An electric hot water system with a storage tank is usually relatively cheap to buy and install, but is usually the most expensive to run.
  • A typical four-person household needs a 125–160L tank for a continuous system or 250–315L for hot water systems that heat overnight.
  • Electric hot water systems can be installed indoors or outdoors.
  • Electric instantaneous water systems are also available.
  • Electric hot water systems range in price from about $300 to $1500 (not including installation).

Electric Hot Water Systems

Gas Hot Water Systems

  • If you have the connection for it, gas is a good option. It’s cheaper than electricity and because gas rates don’t vary through the day, gas hot water systems can heat water as needed.
  • A typical four-person household needs a tank of about 135–170L. You can also choose an instantaneous hot water system..
  • Gas hot water systems are usually installed outdoors due to venting requirements, but can be installed indoors with a flue.
  • Gas hot water systems have an energy efficiency star rating.
  • Some gas hot water systems have a pilot light, which uses a small amount of gas. Hot water systems with electric ignition are more economical, but in a blackout you can lose your hot water supply.
  • Liquid petroleum gas (LPG) bottles are an alternative to natural gas – but expect to pay significantly more in running costs.
  • Gas hot water systems range in price from about $900 to $2000 (not including installation).

Gas Hot Water Systems

Storage tank or instantaneous hot water system?

Your next decision after choosing the heating method, is whether you go for a hot water system with a tank, or one that heats water instantaneously.

Storage Tank Hot Water Systems

Storage Tank

  • Most electric, gas or solar hot water systems use a tank.
  • Mild-steel tanks can corrode over time. It’s important to conduct maintenance every few years to help prevent this. They usually have 5 to 10-year warranties.
  • Stainless steel tanks are more expensive, but generally last longer and don’t require as much maintenance as mild-steel tanks. They usually carry a 10-year warranty, but will still require occasional maintenance (such as replacing valves and seals).
  • Although tanks are insulated, there will always be some heat loss over time. Therefore, it’s good to install storage tanks in a sunny spot or in an insulated space.

Instantaneous Hot Water Systems


  • An instantaneous hot water system heats only as much water as you need, when you need it.
  • Most instantaneous hot water systems use gas, but electric models are available too.
  • As there are no heat losses as with water stored in a tank, they’re often cheaper to run than storage systems.
  • Electric hot water systems may have higher running costs because you are charged whenever they are in use.
  • The size of instantaneous hot water system you need (flow rate in litres per minute) depends upon the number of hot water outlets the heater has to serve, more than on the number of people in the household. As a general rule, for a two-bathroom house you need a flow rate of about 22–24 L/min. Talk to your Know Hot Water Specialist to find the right capacity for your home..

Call Us