At home

Choosing a hot water system

The most suitable hot-water storage system for you will mainly depend on the size of your household and the number of water-consuming appliances in regular use.

Most suitable for households with higher hot water consumption, storage systems work by heating water and storing it in a tank for use as required. Alternatively, continuous flow (also known as ‘instantaneous’) hot water systems are best for smaller homes with lower requirements. They heat only on demand, so don’t waste energy (and your money) by heating water that isn’t used.

Smarter Choice star rating logo

Whichever system you choose, purchase a model with a high energy star rating. The more stars, the more energy efficient the water heater and the lower its greenhouse gas emissions.

Comparison of costs

When choosing a hot water storage system, take into account the purchase price, installation and running costs, and the life expectancy of the unit. Use the Enery Rating Calculator to compare the energy running costs of different systems.

The tables (below) will help you estimate the size of system your household requires and the ongoing water costs, according to the energy source and the number of people being served.

Households with higher than average water consumption should select the next largest system size in the range. A dishwasher with a hot-water connection counts as an extra person.

Gas water heaters

Storage

Continuous flow

Max no. of persons served

Capacity (litres)

Max no. of outlets served
at one time*

Flow rate (litres
per minute)

3

90

1

16

4

130

2

20

5

170

3+

24

6

200

-

-

9

260

-

-

* Continuous flow systems are sized according to the required flow rate. A guide is often the number of bathrooms in the home. Consult suppliers of manufacturers for specific sizing guidelines for their products.

Solar water heaters

No. of persons served

Capacity (litres)

Size of sunlight collector panel required (m2)

1-2

160-200

2

3-4

300-370

4

5-6

440

6

Electric storage water heaters (including heat pump)

Off Peak*

Peak

Max no. of persons served

Capacity (litres)

Max no. of persons served

Capacity (litres)

3

160

2

40

4

250

3

63

6

315

4

80

8

400

5

125

* High-volume water-users (e.g. with a hot-water spa or dishwasher) should select the next largest system size in the range

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Page last updated: 10 December 2015