Hot Water Heater Systems: Electric, Gas, Heat Pump and Solar Options Explained
Hot water heater systems come in several main types: electric storage, gas storage, instant gas, instant electric, heat pump and solar hot water. Each system heats water differently, has different installation requirements and suits different homes.
The best hot water heater system for your home depends on your household size, number of bathrooms, shower habits, energy source, available space, water pressure, gas type, electrical requirements, drainage, access and long-term running cost goals.
Installed Today makes it easy to compare and order hot water systems online, including electric hot water systems, gas hot water systems, instant gas hot water systems and heat pump hot water systems. Supply-only ordering is available across major Australian metro areas, with selected supplied-and-installed options available on eligible products in Brisbane and Gold Coast service areas.
Quick Answer: What Are the Main Hot Water Heater Systems?
The main hot water heater systems are:
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Electric storage hot water systems, which heat and store water in a tank using an electric element
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Gas storage hot water systems, which heat and store water in a tank using natural gas or LPG
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Instant gas hot water systems, which heat water as it flows through the unit
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Instant electric hot water systems, which heat water on demand for selected point-of-use applications
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Heat pump hot water systems, which use heat from the surrounding air to help heat stored water
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Solar hot water systems, which use roof-mounted collectors and a booster to heat stored water
There is no single best system for every home. The right choice depends on the property, energy source, household demand and installation conditions.
Storage vs Continuous Flow Hot Water Heater Systems
Hot water heater systems are often grouped into two broad categories: storage systems and continuous flow systems.
Storage Hot Water Systems
Storage systems heat water and keep it in a tank until it is needed.
Storage options include:
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Electric storage hot water
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Gas storage hot water
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Heat pump hot water
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Solar hot water with storage tank
Storage systems can suit homes that want hot water ready for showers, kitchen use, laundry and general household demand. The key is choosing the right tank size. A tank that is too small can run out during peak use, while a tank that is too large may cost more than needed.
Continuous Flow Hot Water Systems
Continuous flow systems heat water as it passes through the unit.
Continuous flow options include:
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Instant gas hot water
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Instant electric hot water for selected applications
Continuous flow systems do not store a full tank of hot water. They can be compact and efficient where sized correctly, but they need the right gas supply, water pressure or electrical capacity depending on the system type.
Electric Hot Water Heater Systems
Electric hot water systems are common in Australian homes. They use an electric element to heat water stored inside a tank.
Electric storage may suit:
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Homes without natural gas or LPG
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Existing electric hot water replacements
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Rental properties
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Simple like-for-like replacements
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Small, medium and larger households
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Homes already wired for electric storage hot water
Common electric storage size categories include:
Popular electric storage options include:
Electric hot water can be practical, but running costs depend on household usage, tariff, tank size and whether the system is correctly matched to demand.
If your old electric system regularly ran out of hot water, do not automatically replace it with the same size.
Gas Hot Water Heater Systems
Gas hot water systems use natural gas or LPG to heat water. They can be storage systems or instant gas systems.
Gas hot water may suit homes that:
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Already have natural gas or LPG
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Want gas storage or continuous flow hot water
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Have suitable outdoor installation space
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Have suitable gas pipe sizing
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Have suitable water pressure
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Want a gas-style replacement
Gas work must be completed by a licensed gas fitter. Natural gas and LPG systems are not interchangeable, so the correct gas type must be selected before ordering.
Gas Storage Hot Water Systems
Gas storage systems heat and store water in a tank. They can suit homes already using gas that want stored hot water ready for daily use.
Gas storage may suit:
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Existing gas storage replacements
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Homes already set up for natural gas or LPG
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Households wanting a tank-style system
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Properties with suitable outdoor space
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Homes where stored hot water suits the usage pattern
Common gas storage categories include:
Popular gas storage options include:
Gas storage systems can be a practical like-for-like option where the old system worked well and the site still suits gas storage.
Instant Gas Hot Water Heater Systems
Instant gas hot water systems, also called continuous flow gas hot water systems, heat water only when a hot tap is turned on.
They do not store a full tank of hot water. Instead, water passes through the unit and is heated by a gas burner and heat exchanger.
Instant gas may suit:
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Homes wanting continuous flow hot water
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Homes with suitable natural gas or LPG
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Homes with suitable gas pipe sizing
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Homes with suitable water pressure
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Properties with outdoor wall space
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Households wanting a compact alternative to a storage tank
Common instant gas sizes include 16L, 20L and 26L.
A 26L instant gas hot water system may suit some family homes, but only where the gas supply and water pressure support the selected unit.
Popular instant gas options include:
External gas hot water units are designed for outdoor installation unless the specific manufacturer model is approved for internal flued installation.
Heat Pump Hot Water Heater Systems
A heat pump hot water system is an electric hot water system that uses heat from the surrounding air to help heat stored water.
It works differently from a standard electric storage system. Instead of relying only on an electric element, a heat pump uses a fan, compressor, refrigerant circuit and heat exchanger to transfer heat into the water.
Heat pump hot water may suit homes that:
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Want to reduce hot water electricity use
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Are replacing an older electric storage system
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Have suitable outdoor space
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Have clear airflow around the unit
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Can manage condensate drainage
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Have suitable electrical supply
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Have a sensible noise location
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Want to pair hot water operation with rooftop solar where timing suits
Heat pump hot water is not automatically the best option for every home. It needs airflow, drainage, access, electrical suitability and noise placement.
Many homes compare:
Popular heat pump options include:
Solar Hot Water Heater Systems
Solar hot water systems use roof-mounted collectors to capture heat from the sun and transfer it into stored water. Most systems include an electric or gas booster for cloudy weather or periods of higher demand.
Solar hot water may suit homes with:
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Suitable roof space
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Good sun exposure
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Minimal shading
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Suitable roof orientation
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A suitable booster setup
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Long-term energy efficiency goals
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Space for collectors and storage
Solar hot water can reduce grid energy use where the property suits the technology, but it is not always the simplest replacement. Roof access, shading, collector placement, booster type, maintenance and upfront cost all matter.
For some homes, a heat pump may be easier to compare because it does not need roof-mounted collectors.
Instant Electric Hot Water Heater Systems
Instant electric hot water systems heat water on demand using electric heating elements. They are usually more relevant for smaller point-of-use applications than full whole-home shower demand.
Instant electric hot water may suit:
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Small sinks
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Offices
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Kitchenettes
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Granny flats
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Low-demand fixtures
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Point-of-use hot water
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Space-limited applications
Instant electric systems can have high electrical requirements. A licensed electrician or installer should confirm whether the property can support the selected unit before ordering.
Electric vs Gas vs Heat Pump vs Solar Hot Water
| System Type | Best Suited To | Key Checks |
|---|---|---|
| Electric storage | Simple replacements and homes without gas | Tank size, electrical supply, access and drainage |
| Gas storage | Homes with natural gas or LPG wanting stored hot water | Correct gas type, outdoor location and valve setup |
| Instant gas | Continuous flow hot water where gas supply suits | Gas pipe sizing, water pressure and correct gas type |
| Heat pump | Energy-focused homes with suitable outdoor space | Airflow, drainage, access, noise and electrical suitability |
| Solar hot water | Homes with suitable roof space and sun exposure | Roof orientation, shading, booster and collector setup |
| Instant electric | Small point-of-use applications | Electrical capacity, circuit requirements and flow rate |
The best hot water heater system is the one that fits your home’s demand and site conditions, not just the one with the lowest upfront price.
Choosing the Right Size Hot Water Heater System
Correct sizing is one of the most important parts of choosing a hot water system.
A system that is too small may run out during peak use. A system that is too large may cost more than needed or may not suit the available space.
When choosing size, consider:
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Number of people in the home
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Number of bathrooms
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Shower length
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Bath use
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Kitchen use
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Laundry use
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Morning and evening peak demand
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Whether multiple showers run at once
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Existing system size
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Whether the old system ran out of hot water
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Available energy source
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Installation space
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Recovery rate
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Water pressure
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Gas pipe sizing where relevant
For electric storage, many homes compare 250L, 315L and 400L systems.
For heat pumps, many homes compare 200L–280L and 280L-plus systems.
For instant gas, common sizes include 16L, 20L and 26L.
Hot Water Heater Systems for Small Homes
Small homes may suit:
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Smaller electric storage systems
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16L instant gas where gas supply is suitable
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Compact instant electric systems for small point-of-use needs
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Selected heat pumps where outdoor space and airflow suit
Avoid oversizing unless household demand is likely to increase. Oversizing can increase product cost and may not improve comfort.
Hot Water Heater Systems for Family Homes
Family homes usually need more careful sizing because hot water demand often peaks in the morning and evening.
Common options include:
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250L electric storage
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315L electric storage
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Medium heat pump hot water
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20L instant gas
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26L instant gas where the site supports it
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Gas storage where natural gas or LPG is available
If your current system runs out of hot water, review the size and system type before ordering a replacement.
Hot Water Heater Systems for Larger Homes
Larger homes may need:
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315L or 400L electric storage
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Larger heat pump systems
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26L instant gas where gas pipe sizing and water pressure support it
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Larger gas storage options
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Installer review of pipework, gas supply, water pressure and fixture demand
Do not choose the largest system automatically. The system still needs to suit the property.
Hot Water Heater Systems for Homes Without Gas
Homes without gas usually compare:
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Electric storage hot water
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Heat pump hot water
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Instant electric hot water for small point-of-use applications
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Solar hot water where roof conditions suit
Electric storage can be a simple replacement. Heat pump hot water may be worth comparing if the home has suitable outdoor space, airflow, drainage and electrical supply.
Hot Water Heater Systems for Homes With Natural Gas
Homes with natural gas may compare:
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Gas storage hot water
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Instant gas hot water
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Heat pump hot water if moving toward electric-style hot water
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Electric storage where a simple non-gas replacement is preferred
If choosing instant gas, confirm gas pipe sizing and water pressure before ordering.
Hot Water Heater Systems for LPG Homes
Homes using LPG must choose LPG-compatible hot water systems. Natural gas and LPG models are different.
LPG hot water may suit:
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Homes using bottled gas
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Rural or semi-rural properties
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Homes without natural gas connection
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Properties already set up for LPG hot water
Always confirm the correct LPG model before ordering. Gas work must be completed by a licensed gas fitter.
Hot Water Heater Systems for Solar Homes
Homes with rooftop solar may compare heat pump hot water or electric storage timing options.
Heat pump hot water can pair well with rooftop solar where:
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Timer settings suit household usage
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The system can run during stronger solar generation periods
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Electrical setup is suitable
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The tank size and recovery suit the household
This does not mean hot water is automatically free. Product cost, installation, maintenance and electricity use still matter.
Installation Requirements
Hot water heater system installation depends on the system type and property.
Before ordering, check:
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Current system type
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Current system location
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Indoor or outdoor suitability
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Access for delivery
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Access for future servicing
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Electrical requirements
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Gas pipe sizing where relevant
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Water pressure
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Existing valves
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Drainage and overflow points
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Condensate drainage for heat pumps
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Roof suitability for solar
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Whether the system is being relocated
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Whether old unit removal is required
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Whether disposal is included
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Whether compliance upgrades are needed
Hot water systems involve plumbing, electrical work, gas fitting, water pressure, valves and drainage. Use licensed trades where required.
Supply-Only vs Supplied-and-Installed
Installed Today offers supply-only ordering across major Australian metro areas. This can suit customers who already have a licensed installer organised and want to order the product online.
Supply-only may suit you if:
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Your installer has confirmed the correct product
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The system size suits your household
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The correct gas type has been selected where relevant
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Electrical requirements have been checked
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Water pressure has been reviewed
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Access and drainage are suitable
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You understand what is not included in the product price
Selected supplied-and-installed options are available on eligible products in Brisbane and Gold Coast service areas. Availability depends on the product, address and installation requirements.
What Is Not Included in Supply-Only Hot Water Pricing?
For supply-only products, the listed product price generally covers the product only.
It does not usually include:
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Installation labour
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New valves
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Electrical work
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Gas work
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Plumbing alterations
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Pipework changes
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Drainage changes
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Condensate drainage for heat pumps
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Tempering valve upgrades
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Pressure limiting valve upgrades
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Expansion control valves
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Old unit removal
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Disposal
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Compliance upgrades
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Concrete bases or slab work
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Relocation of the system
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Rebate administration
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Site assessment
Always confirm full installation requirements with your licensed installer before ordering supply only.
Rebates, STCs and Incentives
Some hot water heater systems, especially heat pumps and solar-style upgrades, may be eligible for rebates, STCs or other incentives depending on the product, location, supplier pathway and current program rules.
These incentives can change.
Before relying on a rebate or discount, confirm:
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Whether the selected product qualifies
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Whether your property qualifies
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Whether the old system type matters
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Whether supply-only purchases are eligible
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Whether an approved supplier or installer is required
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Whether pre-approval is needed
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Whether the incentive is applied upfront or claimed later
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Whether the rebate or STC value is already included in the price
A rebate can improve value, but the system still needs to suit the home.
Maintenance and Long-Term Performance
A hot water heater system needs maintenance to perform safely and reliably. Maintenance requirements vary by system type, water quality, model and installation location.
General maintenance considerations include:
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Checking for leaks
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Watching for rust or corrosion
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Keeping the area around the unit clear
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Following manufacturer servicing guidance
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Checking valves where required
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Checking the anode where applicable
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Keeping heat pump airflow clear
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Checking condensate drainage for heat pumps
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Using a licensed gas fitter for gas systems
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Using a licensed electrician for electrical faults
Do not attempt plumbing, gas or electrical repairs yourself.
Safety Considerations
Hot water systems must be installed and maintained safely.
Important safety checks include:
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Correct temperature control
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Tempering valve requirements
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Safe delivery temperature
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Pressure relief valve operation
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Drainage and overflow
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Gas leak safety where gas is used
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Electrical isolation
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Manufacturer clearance requirements
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Correct external or internal-flued gas model
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Safe access for servicing
External gas hot water units must not be installed indoors unless the specific model is approved for internal flued installation.
Brand Options to Compare
Installed Today stocks a range of major hot water brands, including:
Brand matters, but system type, size, gas type, water pressure, installation location and household demand matter more than brand alone.
Brisbane and Gold Coast Considerations
For Brisbane and Gold Coast homes, hot water system choice often depends on the existing unit, outdoor space, access, drainage and energy source.
Common considerations include:
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Replacing older electric storage systems
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Comparing electric storage with heat pump upgrades
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Natural gas vs LPG availability
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Outdoor wall space for instant gas
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Gas pipe sizing for 26L systems
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Heat pump airflow and noise placement
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Condensate drainage
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Tight side access
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Existing valve condition
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Old unit removal and disposal
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Whether the selected product is eligible for supplied-and-installed options
Installed Today offers selected supplied-and-installed options on eligible products in Brisbane and Gold Coast service areas, with supply-only ordering available across major Australian metro areas.
Common Mistakes When Choosing Hot Water Heater Systems
Choosing Only by Product Price
A cheap system may cost more long term if it is undersized, inefficient or unsuitable for the property.
Replacing the Same Size Without Checking Demand
If the old system ran out of hot water, the same size may not be enough.
Ignoring Gas Type
Natural gas and LPG systems are different. Always choose the correct model.
Choosing 26L Instant Gas Without Checking the Site
A 26L instant gas system needs suitable gas pipe sizing and water pressure.
Choosing Heat Pump Without Checking Location
Heat pumps need clear airflow, condensate drainage, access, electrical suitability and sensible noise placement.
Assuming Instant Electric Suits the Whole Home
Instant electric systems can have high electrical demand and may be better suited to point-of-use applications.
Assuming Rebates Are Guaranteed
Rebates, STCs and incentives can change and may depend on product, location, supplier and installer pathway.
Assuming Supply-Only Includes Installation
Supply-only generally means product only unless installation is selected or clearly shown.
Before Ordering Checklist
Before ordering a hot water heater system, confirm:
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Current system type
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Current system size
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Whether the old system ran out of hot water
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Number of people in the home
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Number of bathrooms
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Shower habits
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Peak hot water demand
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Electric, natural gas or LPG availability
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Correct gas type where relevant
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Electrical requirements
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Gas pipe sizing for instant gas
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Water pressure
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Heat pump airflow and drainage
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Outdoor or indoor suitability
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Access for delivery and installation
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Drainage and overflow requirements
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Whether new valves may be needed
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Whether old unit removal is included
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Whether disposal is included
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Whether rebates or STCs may apply
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Whether supply-only affects rebate eligibility
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Whether supply-only or supplied-and-installed is the right option
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Installer confirmation before buying supply only
Frequently Asked Questions
What are hot water heater systems?
Hot water heater systems are appliances that heat water for showers, baths, kitchens, laundries and household use. Common types include electric storage, gas storage, instant gas, instant electric, heat pump and solar hot water.
What is the best hot water heater system?
The best hot water heater system depends on your household size, bathrooms, shower habits, energy source and installation location. There is no single best system for every home.
Is electric or gas hot water better?
Electric hot water can suit homes without gas or simple replacements. Gas hot water can suit homes already set up for natural gas or LPG. Natural gas and LPG systems are not interchangeable.
Are heat pump hot water systems worth it?
A heat pump may be worth considering if your home has suitable outdoor space, airflow, condensate drainage, electrical supply and noise placement. It may reduce electricity use compared with standard electric storage in the right location.
Is solar hot water better than heat pump hot water?
It depends on the property. Solar hot water needs suitable roof space, sun exposure and booster planning. Heat pumps need suitable outdoor space, airflow, drainage and electrical supply.
What size hot water heater system do I need?
The right size depends on people in the home, bathrooms, shower habits, bath use, peak demand and whether the old system ran out. Common options include 250L, 315L and 400L electric storage, 200L–280L heat pumps and 16L to 26L instant gas systems.
Is instant gas hot water good for families?
Instant gas can suit some families where the system is correctly sized and the property has suitable gas supply and water pressure. Larger homes often compare 26L systems.
Can I use LPG with a natural gas hot water system?
No. Natural gas and LPG systems are different. Always select the correct gas type.
Does supply-only hot water pricing include installation?
No. Supply-only generally means the product only unless installation is selected or clearly shown. Installation, valves, electrical work, gas work, pipework, drainage, removal, disposal and compliance upgrades are usually separate.
Can I install a hot water heater system myself?
No. Hot water systems involve plumbing, gas, electrical work, water pressure, valves, drainage and compliance requirements. Use licensed trades where required.
Final Word
Hot water heater systems are not one-size-fits-all. Electric storage, gas storage, instant gas, heat pump, solar and instant electric systems all suit different homes, budgets and installation conditions.
The best system is the one that matches your household demand, energy source, installation location and long-term goals. A low product price can become expensive if the unit is the wrong size, wrong gas type or unsuitable for the property.
Before ordering supply only through Installed Today, confirm the selected product with your licensed installer. If choosing a supplied-and-installed option in an eligible Brisbane or Gold Coast service area, check exactly what is included before placing the order.
