Australian homes typically run one of four hot water system types: heat pump, instantaneous gas, gas storage, or electric storage. Each uses a different heat source and storage approach, and each comes with its own cost profile, lifespan, and best-fit scenario.
Choosing the right hot water system comes down to three things: your energy source, how much hot water your household uses, and what you want to pay over the life of the system. Get those three right and everything else falls into place. We cover all the main types below, so you can walk away clear on which one suits your home.
Heat Pump Hot Water Systems
A heat pump extracts warmth from the surrounding air to heat a storage tank, using the same refrigeration cycle as a reverse-cycle air conditioner. It is the system type we recommend most often at TempcoFRH Energy Solutions, and for most households in our region it delivers the strongest balance of running cost and reliability.
How it works
Refrigerant circulates through an outdoor evaporator coil, absorbing ambient heat from the air. A compressor raises the refrigerant temperature, and a heat exchanger transfers that heat to the water in the tank. Because the system moves existing heat rather than generating it, it produces roughly three to four units of heat energy for every one unit of electricity consumed.
Pros
- Running costs around 60 to 75% less than conventional electric storage on the same tariff
- Works without a gas connection, well suited to all-electric homes and new builds
- Pairs with rooftop solar to reduce running costs further, especially during off-peak heating cycles
- Government incentives may reduce the upfront cost; ask us at quote time for current details
Cons
- Higher purchase price than electric or gas storage, typically ~$3,500 to $6,500 or more before installation
- Needs outdoor or well-ventilated space; not suitable for confined indoor cupboards
- Produces operational noise similar to a small air conditioner unit
Best for
Most Australian households, particularly those replacing an electric storage system where the running cost saving is largest. Also the default recommendation for new builds without gas.
If you are weighing it against instantaneous gas, our heat pump vs instantaneous gas comparison covers the trade-offs in detail.
Instantaneous Gas Hot Water Systems
Instantaneous gas systems, also called continuous flow, heat water on demand with no storage tank. Hot water is available the moment a tap opens and there is no volume limit, which is what distinguishes this system from any tank-based option.
How it works
When a hot tap opens, a flow sensor triggers the gas burner. Water passes through a compact heat exchanger and exits at the set temperature. Flow rate is measured in litres per minute; a higher-rated unit can supply multiple outlets simultaneously. The burner cuts out the instant flow stops, so gas is consumed only while water is moving.
Pros
- Lifespan of approximately 15 to 20 years with regular servicing, longer than any storage tank.
- No standby heat loss at all; the system consumes no energy between uses
- Wall-mounted and compact; requires no floor space for a tank
- Can operate during a power outage on models with a standing pilot or battery ignition
Cons
- Requires a gas connection; LPG is available for properties off the mains network but at higher cost
- Flow rate caps out; very large households running several showers at once may need a high-capacity unit or two systems
- Gas tariffs have risen significantly in NSW in recent years, which narrows the running cost advantage over heat pump in some scenarios
Best for
Homes already on a gas connection where continuous supply is the priority and floor space is limited. A strong choice for families with peak morning demand and properties where outdoor space for a heat pump tank is not available.
Gas Storage Hot Water Systems
Gas storage systems use a burner to heat water in an insulated tank and keep it ready until needed. They are familiar and widely supported, but they carry a structural efficiency disadvantage that instantaneous gas and heat pumps do not share.
How it works
A thermostat monitors tank temperature and fires the gas burner to reheat whenever it drops. Fire safety regulations require the base of the tank to remain uninsulated, which creates a constant path for heat loss. The burner cycles on and off around the clock to compensate, regardless of whether hot water is being used.
Pros
- Wide installer support and long service history across Australia
- Faster recovery than electric storage; the gas burner reheats a depleted tank in around an hour
- Straightforward like-for-like replacement where gas pipework is already in place
Cons
- Continuous standby heat loss from the uninsulated base means the burner runs even overnight
- Higher running costs than instantaneous gas in most households over the life of the system
- Tank lifespan of approximately 8 to 12 years, shorter than instantaneous systems
Best for
Homes replacing a like-for-like gas storage unit where switching technology is not practical. For most new installations, instantaneous gas or a heat pump is worth considering first.
Electric Storage Hot Water Systems
Electric storage systems heat water with a resistive element inside a tank, the same principle as a kettle. They are the cheapest option to purchase and install, but carry the highest running costs of any system type on a standard tariff.
How it works
The element runs on grid electricity and heats the tank to a set temperature. Most systems can be configured to run on an off-peak tariff, meaning the tank reheats during low-cost overnight hours and stores that hot water for daytime use. Connected to a rooftop solar system and set to heat during peak solar output, running costs can fall close to heat pump levels.
Pros
- Lowest upfront cost of any system type, typically ~$900 to $2,500 before installation
- Simple to install and service; no specialist gas or refrigeration skills required
- Off-peak tariff scheduling reduces energy cost without changing the hardware
Cons
- On a standard peak tariff, running costs are the highest of any system type
- Off-peak scheduling means water is only heated at set times, which can fall short on high-demand days
- Tank lifespan of approximately 8 to 12 years, the same as gas storage
Best for
Homes with a generous rooftop solar setup and the ability to schedule tank heating during peak solar output hours. Without solar or an off-peak tariff, most households will recover the cost difference of a heat pump through running cost savings within a few years.
If you are comparing the lifespan across different types, our guide on how long a hot water system lasts can be worth reading.
Quick Comparison: Hot Water System Types at a Glance
| System Type | Upfront Cost | Running Cost | Lifespan | Best Suited To |
|---|---|---|---|---|
| Heat Pump | ~$3,500 to $6,500+ | Low | ~10 to 15 yrs | Most households; especially electric storage replacements |
| Instantaneous Gas | ~$1,000 to $3,000+ | Low to Medium | ~15 to 20 yrs | Gas-connected homes; families wanting continuous supply |
| Gas Storage | ~$1,500 to $3,500+ | Medium | ~8 to 12 yrs | Like-for-like gas storage replacements |
| Electric Storage | ~$900 to $2,500+ | High | ~8 to 12 yrs | Homes with rooftop solar; budget-constrained installs |
Note: All figures are approximate purchase price ranges excluding installation. Costs vary by model, capacity, and site.
Our guide on hot water system size can help you choose the right size system according to your family needs.
How to Choose the Right Hot Water System for Your Home
The right hot water system depends on your specific situation. These are the four questions worth working through before you decide.
1. Do you have a gas connection?
No gas means the heat pump is the clear front-runner. With gas, the choice between instantaneous and heat pump comes down to budget, space, and whether you want to stay on gas long-term given current tariff trends.
2. How much hot water does your household use?
Tank-based systems need to be sized to cover peak daily demand; run short too often and you are effectively paying for standby heat you did not use. Instantaneous gas sidesteps the sizing question entirely since there is no tank to run out of.
3. What space and site constraints do you have?
Heat pump tanks need outdoor or well-ventilated space; they cannot go in a sealed cupboard. Instantaneous gas units are wall-mounted and take up minimal space. If the installation site is constrained, that may settle the question before anything else does.
4. What is your budget over the life of the system?
The cheapest system to buy is the most expensive to run, and vice versa. Heat pump costs more upfront but typically recovers the difference through lower running costs within a few years.
For a full breakdown, see our article on hot water installation costs in Australia.
| INSTALLER TIP: Tempco FRH Energy installs and repairs hot water systems across Australia. For most Southern Highlands homes we install today, a cold-climate heat pump is our first recommendation. If the property is on natural gas and outdoor space is limited, instantaneous gas is the next call. |
Frequently Asked Questions
Which hot water system type is cheapest to run in Australia?
Heat pump hot water systems generally have the lowest running costs of any type, using around 60 to 75% less electricity than a conventional electric storage system. The exact figure depends on your tariff, household size, and whether you have rooftop solar. Instantaneous gas is competitive for households with a natural gas connection.
Is a heat pump hot water system suitable for cold climates like the Southern Highlands?
Yes, provided you select a model rated for cold-climate operation. We specify cold-climate rated units as standard for Southern Highlands installations. Your installer will confirm the right specification for your site.
What is the difference between instantaneous and storage hot water systems?
Storage systems heat water in advance and keep it ready in an insulated tank. Instantaneous systems, also called continuous flow, heat water on demand as you use it with no tank at all. Storage systems can run short if demand exceeds tank capacity. Instantaneous systems provide a continuous supply but require adequate gas pressure and flow rate.
How long does a hot water system last?
Storage systems, both gas and electric, typically last approximately 8 to 12 years. Heat pump systems average approximately 10 to 15 years. Instantaneous gas systems generally last approximately 15 to 20 years with regular servicing. Maintenance makes a real difference to lifespan across all types.
Can I switch from gas to a heat pump hot water system?
Yes. Heat pump systems run on electricity, so no gas connection is needed. The switchover is straightforward in most homes. It is one of the more common upgrades we carry out across the Southern Highlands, particularly as households look to reduce running costs over time.
Do I need a plumber or an electrician to install a hot water system?
Hot water system installation in NSW requires a licensed tradesperson, typically a licensed plumber, with an electrician required for any electrical connections. TempcoFRH Energy Solutions manages the full installation process, including coordination of trades where required.