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What size hot water system is right for me?

Hot water systems are as varied as the households that need them. Big family homes, to small studio apartments, townhouses which are home to 3 generations to units for couples, every home has different hot water habits and requirements. So how do you find the right hot water system for your home? We recommend speaking to your local hot water specialists for expert advice specific to your requirements. But before you hit up the experts here are our tips on choosing the right hot water system for your home.

Things to consider

  • How many people live in your house or apartment? More people usually equals a bigger unit, however, if you’re a family of 6 water conservationists who take 3 min showers you could keep the size down. (There is always an exception to the rule, this is why speaking to your local hot water team is a great idea.)
  • Do some of those people who like to take long showers or big baths every night?
  • How many bathrooms/showers in your home? Do they all get used at once? Sometimes? Always? Boost the size of your hot water system to avoid running out.
  • Does your family shower, use the dishwasher, and throw a load of washing on all at the same time? In the morning before work and school or in the evening when everyone gets in? High demand periods need a lot of hot water.
  • When does your household use most of their hot water - in the evening or in the morning? This can affect the suitability and efficiency of solar hot water.
  • Are you considering connecting the hot water system to an off-peak electricity tariff? You’ll need a bigger tank to cater for use during peak (non-heating) periods.
  • Does your home have a spa bath? Spa’s or large baths can use a huge amount of hot water to fill.
  • Do you live in a warm or cool climate? The ambient temperature of the water can affect the efficiency of some types of hot water systems. (Tip - Sydney is classed as a cool climate)
  • Are you planning on expanding your household in the next 10 years? Your hot water system will last at least that long probably longer if you look after it, so make sure it will cater for the future growth of your family.
  • Are you thinking of selling your home in the next 10 to 15 years? Consider the needs of future occupants or potential buyers.

Recommended size guide for instant hot water systems

No. of showers 12 litre 16 litre 20 litre 26 litre 32 litre
Warm climate 1 1 1 - 2 1 - 3 1 - 4
Cool climate 1 1 1 1 - 2 1 - 3

Storage electric hot water sizing guide

Tank Size  No. people - peak tariff    No. people - off-peak tariff   
  Warm Climate Cool Climate  Warm Climate Cool Climate 
50L 1 1 - -
80L 2 - 3 1 - 2 1 - 2 -
125L 3 - 4 2 - 3 2 - 3 1 - 2
160L 4 - 5 3 - 4 3 - 4 2 - 3
200L 6 - 7 4 - 5 4 - 5 3 - 4
250L 7 - 8 5 - 6 5 - 6 4 - 5
315 8 - 9 6 - 7 6 - 7 5 - 6
400 10 + 8 + 8 + 6 +

Gas storage hot water system size guide

Tank Size Cool Climate Warm Climate
135L 1 - 4 1 - 5
170L 1 - 5 1 - 6

Solar hot water size guide

Tank Size No. people Booster Collector panels
160L 2 - 5 Gas 2
180L 1 - 2 Gas or electric peak 1
270L 2 - 5 Gas or electric peak 2
300L 2 - 5 Gas or electric peak 2
335L 2 - 6 Electric 2
410L 3 - 7 Electric 2

Heat pump water heater size guide

Tank Size No. people
160L 2 - 4
250L 3 - 5
300L 4 - 6
315L 4 - 6

FIND OUT EXACTLY WHAT HOT WATER SYSTEM WILL SUIT YOUR HOME

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Refs - https://www.rinnai.com.au/wp-content/uploads/RIN_METZ3051_Hot-Water-Reference-Guide_Update_FINAL_web.pdf; https://www.sanden-hot-water.com.au/why-choose-sanden-heat-pumps; https://www.rheem.com.au/products