Best Gas Water Heater: How to Choose Between Instant Gas and Gas Storage Hot Water

Dec 1, 2024

A gas water heater can be a practical choice for homes with natural gas or LPG, especially where the household needs strong hot water recovery, compact outdoor installation or a like-for-like replacement of an existing gas system.

The best gas water heater depends on your gas type, household size, number of bathrooms, shower habits, water pressure, gas pipe sizing, installation location and whether you want instant gas hot water or a gas storage tank.

Installed Today helps customers compare gas hot water systems, instant gas hot water systems, 26L instant gas hot water systems and broader hot water systems online.

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 where shown.

Quick Answer

The best gas water heater is the one that matches your household demand and gas setup.

Choose an instant gas water heater if:

You want compact continuous flow hot water
The home has suitable natural gas or LPG
Gas pipe sizing is suitable
Water pressure is suitable
Outdoor wall space and clearances are available
You are replacing an existing continuous flow gas unit

Choose a gas storage water heater if:

You are replacing an existing gas storage tank
You want stored hot water
The existing outdoor tank location is suitable
The home already has natural gas or LPG
Continuous flow is not the preferred option

Natural gas and LPG are not interchangeable. Gas work must be completed by a licensed gas fitter.

What Is a Gas Water Heater?

A gas water heater uses natural gas or LPG to heat water for showers, basins, kitchens and laundries.

There are two main types of domestic gas water heaters:

Instant gas water heaters
Gas storage water heaters

An instant gas water heater heats water on demand as it flows through the unit. A gas storage water heater heats and stores water in a tank.

Both types can work well in the right home, but they suit different properties and usage patterns.

Instant Gas Water Heaters

Instant gas water heaters are also called continuous flow gas hot water systems or tankless gas water heaters.

They heat water when a hot tap is turned on. Water flows through the unit, a gas burner heats the heat exchanger, and hot water is delivered to the outlet.

Instant gas water heaters may suit:

Homes with natural gas or LPG
Customers wanting a compact wall-mounted system
Like-for-like replacement of an existing continuous flow unit
Homes with suitable gas pipe sizing
Homes with suitable water pressure
Outdoor installations with compliant clearances
Households wanting hot water heated on demand

Customers can compare instant gas hot water systems, including 26L instant gas hot water systems.

Gas Storage Water Heaters

Gas storage water heaters heat and store water in a tank. The stored hot water is available for use until the tank is depleted, then the system reheats.

Gas storage water heaters may suit:

Like-for-like gas storage replacements
Homes with natural gas or LPG
Customers wanting a familiar tank-style system
Properties with a suitable existing tank location
Homes where continuous flow pipe sizing or pressure is not ideal
Households with predictable stored hot water demand

Customers comparing gas storage options can browse 130/135L gas hot water systems, 160/170L gas hot water systems and 5-star gas hot water systems.

Instant Gas vs Gas Storage

Instant Gas May Suit:

Compact outdoor wall-mounted installation
Homes with suitable gas pipe sizing
Homes with suitable water pressure
Continuous flow hot water within the unit’s rated capacity
Customers replacing an existing instant gas unit
Homes where tank space is limited

Gas Storage May Suit:

Like-for-like tank replacement
Homes wanting stored hot water
Properties with an existing gas storage location
Homes where instant gas is not practical
Customers who prefer a tank-style system

The better choice depends on gas type, water pressure, household demand and installation requirements.

Does Instant Gas Mean Endless Hot Water?

Instant gas systems do not run out in the same way as a storage tank, but they are not unlimited.

Every instant gas water heater has a rated flow capacity. If too many outlets are used at the same time, the system can be exceeded.

Performance can be affected by:

Number of showers running
Showerhead flow rate
Kitchen and laundry use
Water pressure
Gas pipe sizing
Natural gas or LPG supply
Distance from the unit to outlets
Incoming water temperature
Unit size

A 26L gas water heater may suit some higher-demand homes, but only where gas pipe sizing and water pressure are suitable. Bigger is not automatically better.

Best Instant Gas Water Heaters to Compare

There is no single best gas water heater for every home. The right unit depends on demand, gas type and installation conditions.

Rinnai Infinity B26 Natural Gas Water Heater

The Rinnai Infinity B26 Natural Gas Hot Water System may suit customers comparing a 26L natural gas continuous flow water heater.

It may suit:

Medium to larger households
Homes with natural gas
Properties with suitable gas pipe sizing
Homes with suitable water pressure
Customers replacing an existing 26L gas unit
Outdoor wall-mounted installations

For 26L systems, gas pipe sizing and water pressure must be checked before ordering.

Rinnai Infinity B26 LPG Water Heater

The Rinnai Infinity B26 LPG Gas Hot Water System may suit homes using LPG bottles where a higher-capacity continuous flow unit is needed.

It may suit:

LPG homes
Rural or acreage properties
Medium to larger households
Customers replacing an LPG continuous flow unit
Outdoor wall-mounted installations

LPG bottle setup, regulator suitability, gas pipe sizing and water pressure should be confirmed by a licensed gas fitter.

Rheem 26L Natural Gas Water Heater

The Rheem 26L Natural Gas Hot Water System may suit homes comparing a larger natural gas continuous flow option.

It may suit:

Natural gas homes
Higher hot water demand
Properties with suitable pipe sizing
Homes with suitable water pressure
Customers comparing Rheem instant gas systems

Multiple hot water outlets can still exceed capacity, so sizing should be checked against real household use.

Rheem 26L LPG Water Heater

The Rheem 26L LPG Gas Hot Water System may suit LPG homes where gas supply and water pressure support a 26L system.

It may suit:

LPG bottle properties
Medium to larger households
Outdoor installations
Customers wanting an LPG continuous flow option
Homes where gas supply has been checked

Natural gas and LPG models are different. Always order the correct gas type.

Rheem 20L Natural Gas Water Heater

The Rheem 20L Natural Gas Hot Water System may suit small to medium homes with moderate hot water demand.

It may suit:

Natural gas properties
Smaller to medium households
Moderate shower demand
Like-for-like 20L replacements
Customers who may not need a 26L system

A 20L gas water heater may be more suitable than a larger model where household demand is lower.

Rheem 20L LPG Water Heater

The Rheem 20L LPG Gas Hot Water System may suit LPG homes with moderate demand.

It may suit:

Smaller LPG homes
Outdoor installations
Moderate hot water use
Like-for-like LPG replacement
Customers comparing mid-size LPG systems

LPG regulator setup and gas pipe sizing should be checked before purchase.

Rinnai Infinity B16 Natural Gas Water Heater

The Rinnai Infinity B16 Natural Gas Hot Water System may suit lower-demand natural gas applications.

It may suit:

Small homes
Single bathroom homes
Granny flats
Lower simultaneous hot water use
Like-for-like replacement of a small continuous flow unit

A 16L system may not suit homes where multiple showers or fixtures are used together.

Rinnai Infinity B16 LPG Water Heater

The Rinnai Infinity B16 LPG Gas Hot Water System may suit lower-demand LPG applications.

It may suit:

Small LPG homes
Granny flats
Single bathroom setups
Lower water demand
Compact LPG continuous flow replacements

The LPG setup, regulator and pipework should be checked before ordering.

Bosch 16H Natural Gas and LPG Water Heaters

Customers comparing smaller gas water heaters may also look at Bosch options such as the Bosch 16H Natural Gas Hot Water System and Bosch 16H LPG Gas Hot Water System.

These may suit smaller households or lower-demand applications where the gas type, water pressure and installation location are suitable.

Best Gas Storage Water Heaters to Compare

Gas storage can be a good option where the home already has a storage-style gas system and the household wants a similar replacement.

Rheem 4-Star 135L Natural Gas Water Heater

The Rheem 4-Star 135L Natural Gas Hot Water System may suit customers replacing an existing natural gas storage water heater.

It may suit:

Natural gas homes
Like-for-like gas storage replacement
Outdoor tank locations
Moderate household demand
Customers wanting a familiar tank-style system

If the old 135L gas storage system ran out often, sizing should be reviewed before replacing it with the same capacity.

Rheem 4-Star 135L LPG Water Heater

The Rheem 4-Star 135L LPG Gas Hot Water System may suit LPG homes replacing a gas storage system.

It may suit:

LPG properties
Existing gas storage locations
Like-for-like LPG storage replacement
Moderate stored hot water demand
Customers comparing Rheem LPG storage systems

LPG bottle setup and gas supply should be confirmed before ordering.

Rheem Stellar 330 Natural Gas Water Heater

The Rheem Stellar 330 Natural Gas Hot Water System may suit customers comparing larger natural gas storage options.

It may suit:

Homes with natural gas
Higher stored hot water demand
Larger households where tank-style gas suits
Customers comparing premium gas storage options
Properties with a suitable outdoor tank location

The right choice depends on usage, recovery, location and installation requirements.

Rheem Stellar 360 Natural Gas Water Heater

The Rheem Stellar 360 Natural Gas Hot Water System may suit homes with higher stored hot water demand where a larger natural gas storage system is appropriate.

It may suit:

Larger households
Natural gas properties
Higher daily hot water use
Homes where storage gas is preferred
Customers comparing larger gas storage systems

If multiple bathrooms are used heavily, sizing should still be checked carefully.

Vulcan 4-Star 135L Natural Gas Water Heater

The Vulcan 4-Star 135L Natural Gas Hot Water System may suit customers comparing value-focused gas storage replacements.

It may suit:

Natural gas homes
Like-for-like 135L gas storage replacement
Moderate household demand
Existing tank-style gas installations

Vulcan 4-Star 135L LPG Water Heater

The Vulcan 4-Star 135L LPG Gas Hot Water System may suit LPG homes comparing gas storage options.

It may suit:

LPG properties
Tank-style gas replacements
Moderate stored hot water use
Customers comparing LPG storage water heaters

Vulcan 4-Star 170L Natural Gas Water Heater

The Vulcan 4-Star 170L Natural Gas Hot Water System may suit customers comparing larger Vulcan gas storage options.

It may suit:

Natural gas homes
Larger stored hot water demand
Like-for-like gas storage replacement
Properties with suitable outdoor space

What About Stiebel Eltron?

Stiebel Eltron is more relevant to electric and instant electric hot water than gas water heaters.

If you are comparing compact point-of-use electric systems, browse Stiebel Eltron hot water systems and instant electric hot water systems.

Instant electric is not the same as instant gas. It may suit sinks, kitchenettes, offices and low-demand fixtures, but whole-home instant electric can require significant electrical capacity, dedicated circuits or three-phase power depending on the application.

Natural Gas vs LPG Gas Water Heaters

Natural gas and LPG are different fuels. The gas water heater must match the property’s gas type.

Before ordering, confirm:

Does the home use natural gas or LPG?
Is the selected unit a natural gas or LPG model?
Is the existing system the same gas type?
Is gas pipe sizing suitable?
Is the gas meter or LPG bottle setup suitable?
Are other gas appliances connected?
Is the installation location compliant?
Has a licensed gas fitter confirmed suitability?

Do not order a natural gas model for an LPG property, or an LPG model for a natural gas property.

What Size Gas Water Heater Do You Need?

Gas water heater sizing depends on demand, not just the number of people.

Consider:

Number of occupants
Number of bathrooms
Shower length and frequency
Whether showers run at the same time
Bath use
Kitchen and laundry use
Showerhead flow rates
Existing system size
Whether the old system ran out
Natural gas or LPG
Gas pipe sizing
Water pressure
Distance from unit to outlets

16L Instant Gas

A 16L instant gas water heater may suit:

Small homes
Single bathroom properties
Granny flats
Lower-demand households
Like-for-like smaller instant gas replacements

20L Instant Gas

A 20L instant gas water heater may suit:

Small to medium households
Moderate hot water demand
Homes where a 26L unit is unnecessary
Like-for-like 20L replacements

26L Instant Gas

A 26L instant gas water heater may suit:

Higher-demand households
Multiple bathroom homes where usage is moderate
Larger homes where gas supply is suitable
Like-for-like 26L replacements

For 26L systems, gas pipe sizing and water pressure must be checked. Multiple outlets can still exceed capacity.

135L to 170L Gas Storage

Gas storage systems around 135L to 170L may suit homes replacing an existing gas storage tank, depending on demand and recovery.

If the old system regularly ran out, do not automatically replace it with the same size.

Gas Water Heater vs Electric Water Heater

Gas and electric water heaters suit different homes.

Gas Water Heater May Suit:

Homes with natural gas or LPG
Customers replacing an existing gas system
Homes wanting instant gas continuous flow
Properties with suitable gas pipe sizing
Homes with suitable water pressure
Outdoor installation locations

Electric Water Heater May Suit:

Homes without gas
Like-for-like electric replacements
Customers wanting a familiar storage tank
Properties where gas installation is not practical
Homes where heat pump or instant gas is not suitable

Customers comparing electric alternatives can browse electric hot water systems, including 250L electric hot water systems, 315L electric hot water systems and 400L electric hot water systems.

Gas Water Heater vs Heat Pump Hot Water

A gas water heater may suit homes with natural gas or LPG, while a heat pump may suit homes wanting an efficient electric storage-style option.

Gas May Suit:

Homes already using gas
Customers wanting continuous flow hot water
Properties with suitable gas pipe sizing
Homes with suitable water pressure
Like-for-like gas replacements

Heat Pump May Suit:

Homes without gas
Customers moving away from gas
Properties with outdoor space
Locations with clear airflow
Homes where condensate drainage can be managed
Solar PV homes where timer operation suits usage

Customers can compare heat pump hot water systems, including medium heat pump hot water systems from 200L to 280L and large heat pump hot water systems over 280L.

Installation Requirements for Gas Water Heaters

Gas water heater installation can involve plumbing, gas fitting and sometimes electrical work.

A licensed gas fitter should confirm:

Natural gas or LPG type
Gas pipe sizing
Gas meter or LPG bottle setup
LPG regulator suitability
Appliance gas load
Outdoor location
Clearances
Ventilation requirements
Water pressure
Temperature control requirements
Compliance requirements

Gas work must be completed by a licensed gas fitter. Plumbing work should be completed by a licensed plumber where required. Electrical work must be completed by a licensed electrician where required.

External gas units are designed for outdoor installation unless the specific model is approved for internal flued installation.

Running Costs and Efficiency

Gas water heater running costs vary by home.

Costs can be affected by:

Natural gas prices
LPG bottle prices
Gas supply charges
Household hot water use
Shower length
Number of occupants
System size
Storage vs instant gas
Temperature settings
Water pressure
Pipe runs
Maintenance condition
Other gas appliances

It is not safe to assume gas is always cheaper than electric, heat pump or solar in every property. The best choice depends on energy prices, usage and installation conditions.

Rebates and Incentives

Rebates and incentives can change and do not apply to every hot water system.

Gas water heaters are not automatically eligible for rebates. Some efficient hot water systems, especially selected heat pump or solar products, may be eligible for STCs, rebates or incentives depending on current rules, product type, location and installation details.

Before choosing a system based on incentives, confirm current eligibility and whether any discount is already included in the advertised price.

Maintenance for Gas Water Heaters

Maintenance depends on the system type, water quality, gas supply, usage and manufacturer guidance.

Maintenance may include:

Checking for visible leaks
Monitoring temperature stability
Cleaning inlet filters on continuous flow systems
Watching for error codes
Checking hot water flow
Inspecting valves on storage systems
Servicing gas components where required
Checking ignition issues
Descaling where hard water affects performance
Following manufacturer service guidance

If you smell gas, turn off the gas supply if safe to do so, avoid ignition sources and contact a licensed gas fitter or emergency service as appropriate.

Installed Today is positioned as an online supplier of hot water systems, water filters and pumps, with selected supplied-and-installed options on eligible products in Brisbane and Gold Coast service areas where shown. General repair diagnosis, emergency plumbing and ongoing servicing should be handled by licensed trades where required.

Brisbane and Gold Coast Considerations

In Brisbane and Gold Coast homes, gas water heater suitability can be affected by:

Natural gas availability
LPG bottle setup
Gas meter location
Gas pipe sizing
Water pressure
Narrow side access
Outdoor wall location
Eaves, windows and clearances
Existing valve condition
Coastal exposure on the Gold Coast
Apartment or townhouse restrictions
Whether the old system kept up with demand
Compliance upgrades
Old unit removal

Selected supplied-and-installed options are available on eligible Installed Today products in Brisbane and Gold Coast service areas where shown. Availability depends on the product, address and installation requirements.

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.

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.

For supply-only products, the listed product price generally covers the product only.

It does not usually include:

Installation labour
Plumbing alterations
Electrical work
Gas work
New valves
Pipework changes
Gas pipe upgrades
Drainage changes
Tempering valve upgrades
Pressure limiting valve upgrades
Expansion control valves
Old unit removal
Disposal
Compliance upgrades
Concrete bases or slab work
Flue kits unless listed
Temperature controllers unless listed
LPG bottle supply
LPG regulator upgrades
Relocation of the system
Rebate administration
Site assessment

For gas water heaters, confirm gas type, pipe sizing, water pressure, clearances and installation suitability with a licensed gas fitter before ordering.

Common Gas Water Heater Buying Mistakes

Ordering the Wrong Gas Type

Natural gas and LPG are different. The selected model must match the property.

Choosing 26L Without Checking Gas Pipe Sizing

A 26L instant gas system may need more gas supply than existing pipework can provide.

Assuming Instant Gas Is Unlimited

Instant gas systems can provide continuous hot water within their rated capacity, but too many outlets can still exceed performance.

Replacing Like-for-Like When the Old System Was Too Small

If the old system ran out or temperature fluctuated, the size and setup should be reviewed.

Installing External Gas Units Indoors

External gas units are for outdoor installation unless the model is specifically approved for internal flued installation.

Choosing Based Only on Brand

Brand matters, but gas type, sizing, water pressure, pipework and installation location matter more.

Assuming Supply-Only Includes Installation

Supply-only pricing generally covers the product only unless installation is clearly selected or listed.

Before Ordering Checklist

Before choosing a gas water heater, check:

Is the home natural gas or LPG?
Does the selected model match the gas type?
Is the existing system instant gas, gas storage or electric?
Is the replacement like-for-like?
How many people live in the home?
How many bathrooms are used daily?
Are showers used at the same time?
Does the household use a bath?
Did the old system keep up with demand?
Is gas pipe sizing suitable?
Is LPG regulator setup suitable if applicable?
Is water pressure suitable?
Is the outdoor location compliant?
Are clearances suitable?
Are temperature controllers required?
Is a tempering valve or temperature control device required?
Is old unit removal included or separate?
Is the product supply-only or supplied-and-installed?
Has a licensed gas fitter confirmed suitability?

Frequently Asked Questions

What is the best gas water heater?

The best gas water heater depends on gas type, household demand, water pressure, gas pipe sizing and whether you want instant gas or gas storage. Rinnai, Rheem, Vulcan and Bosch options are commonly compared through Installed Today.

Is an instant gas water heater better than gas storage?

Instant gas may suit homes wanting compact continuous flow hot water. Gas storage may suit like-for-like tank replacements. The better option depends on household use, pipe sizing, water pressure and installation location.

What size instant gas water heater do I need?

Common sizes include 16L, 20L and 26L. The right size depends on bathrooms, shower habits, simultaneous use, gas pipe sizing and water pressure.

Is 26L instant gas suitable for every home?

No. A 26L system may suit higher-demand households, but only where gas supply and water pressure are suitable. Bigger is not automatically better.

Can I use LPG on a natural gas water heater?

No. LPG and natural gas are different. The selected water heater must match the property’s gas type.

Do gas water heaters need electricity?

Some instant gas systems need electricity for ignition, controls or temperature controllers. Check the product specifications and installation requirements.

Can I install a gas water heater myself?

No. Gas water heater installation involves gas fitting and plumbing work. Licensed trades must complete the work where required.

Are gas water heaters cheaper to run than electric?

Not always. Running costs depend on gas prices, electricity tariffs, LPG bottle costs, household usage, system type and installation conditions.

Does supply-only pricing include installation?

No. Supply-only pricing generally covers the product only. It does not usually include plumbing work, gas fitting, electrical work, valves, pipework changes, gas pipe upgrades, drainage, old unit removal, disposal or compliance upgrades unless clearly listed.

Final Word

A gas water heater can be a strong option for homes with natural gas or LPG, but the right system depends on more than brand name or advertised capacity.

Instant gas water heaters can suit compact continuous flow installations where gas pipe sizing, water pressure and outdoor clearances are suitable. Gas storage water heaters can suit like-for-like tank replacements where stored hot water is preferred.

Installed Today makes it easy to compare gas hot water systems, instant gas hot water systems, 26L instant gas hot water systems and broader hot water systems online.

For supply-only orders, confirm gas type, gas pipe sizing, water pressure, clearances and installation requirements with licensed trades before purchasing.

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