Gas Water Heating System: Benefits, Types and What to Check Before You Buy

Oct 24, 2024

A gas water heating system can be a practical option for homes that already have natural gas or LPG available. Gas hot water systems can heat water quickly, suit a range of household sizes and give homeowners the choice between stored hot water and continuous flow hot water.

The right gas hot water system depends on your household size, number of bathrooms, shower habits, gas type, water pressure, gas pipe sizing, outdoor location and whether you are ordering supply only or choosing an eligible supplied-and-installed option.

Installed Today makes it easy to compare and order gas hot water systems, instant gas hot water systems, 26L instant gas hot water systems and hot water systems online, with supply-only ordering available across major Australian metro areas and selected supplied-and-installed options available on eligible products in Brisbane and Gold Coast service areas.

Quick Answer: Is a Gas Water Heating System Right for Your Home?

A gas water heating system may be right for your home if you already have natural gas or LPG, want a gas-style replacement, have suitable outdoor space and your hot water demand matches the selected system.

As a general guide:

Gas storage hot water systems can suit homes that want stored hot water ready for use
Instant gas hot water systems can suit homes wanting continuous flow hot water without a large tank
16L instant gas systems may suit smaller homes or lower-demand applications
20L instant gas systems may suit small-to-medium households
26L instant gas systems may suit some family homes where gas pipe sizing and water pressure support the unit
Natural gas and LPG systems are not interchangeable
Gas work must be completed by a licensed gas fitter
External gas hot water units are outdoor units unless the specific model is approved for internal flued installation

Before ordering supply only, confirm the gas type, model, size, water pressure, gas pipe sizing, location, valves, drainage, access and installation suitability with your licensed installer.

What Is a Gas Water Heating System?

A gas water heating system uses natural gas or LPG to heat water for showers, baths, kitchen taps, laundry and general household hot water use.

Gas hot water systems usually fall into two main groups:

Gas storage hot water systems
Instant gas hot water systems

Gas storage systems heat water and keep it in a tank. Instant gas systems heat water as it flows through the unit when a hot tap is turned on.

Both can work well in the right home. The best choice depends on your existing system, household demand, gas supply, water pressure and installation location.

Natural Gas vs LPG Gas Hot Water

This is one of the most important checks before buying a gas water heating system.

Natural gas and LPG are different fuel types. A natural gas hot water system must not be treated as interchangeable with an LPG system.

Natural gas is supplied through a gas mains connection
LPG is supplied through bottles or cylinders
Natural gas models and LPG models are different
Gas type conversion is only suitable where the manufacturer allows it
Any approved conversion must be completed by a licensed gas fitter
Ordering the wrong gas type can make the unit unsuitable for the property

Installed Today lists natural gas and LPG options separately where available, including products such as the Rinnai Infinity B26 Natural Gas Hot Water System, Rinnai Infinity B26 LPG Gas Hot Water System, Rheem 26L Natural Gas Hot Water System and Rheem 26L LPG Gas Hot Water System.

How Gas Water Heating Systems Work

Gas water heating systems use a gas burner to heat water. The way the system works depends on whether it is storage or instant gas.

Gas Storage Systems

A gas storage system heats water inside a tank and stores it ready for use. When hot water is used, cold water enters the tank and the burner reheats it.

This can suit homes that want stored hot water and are replacing an existing gas storage system.

Instant Gas Systems

An instant gas system heats water only when a hot tap is turned on.

The process usually works like this:

A hot tap or shower is turned on
The unit detects water flow
The gas burner activates
Water passes through a heat exchanger
Heated water flows to the fixture
The unit turns off when demand stops

Instant gas systems are also called continuous flow gas hot water systems because they heat water as it flows through the unit.

Benefits of a Gas Water Heating System

Fast Heating

Gas systems can heat water quickly, which can make them practical for homes with regular shower, kitchen and laundry demand.

Storage and Continuous Flow Options

Gas gives you the choice between a tank-style storage system and a compact instant gas system.

Compact Instant Gas Units

Instant gas systems are usually wall-mounted outdoors, which can save space compared with a large storage tank.

Natural Gas and LPG Models

Gas hot water systems are available in natural gas and LPG models, giving options for homes with different gas supplies.

Practical Replacement Pathway

If your home already has gas hot water and the old system worked well, replacing it with another gas hot water system may be practical where the gas supply, water pressure and installation location remain suitable.

Continuous Flow Potential

A correctly sized instant gas system can provide continuous flow hot water within the unit’s capacity, provided the property has suitable gas pipe sizing and water pressure.

Limitations of Gas Water Heating Systems

Gas hot water is not right for every property.

Potential limitations include:

Natural gas and LPG models are different
Gas work requires a licensed gas fitter
Larger instant gas units may need gas pipe sizing checks
Water pressure must suit the selected unit
External gas units must be installed outdoors unless approved as internal flued models
Location and clearances matter
Some systems may need electrical connection for ignition or controls
Pipework, valves or drainage may need upgrading
LPG running costs depend on bottle supply and household usage
Homes without gas may be better comparing electric storage or heat pump hot water

The best gas water heating system is the one that suits both the household and the property.

Gas Storage Hot Water Systems

Gas hot water systems include storage and instant options. Gas storage systems heat water in a tank and keep it ready for use.

Gas storage may suit homes that:

Already have natural gas or LPG
Want a tank-style replacement
Prefer stored hot water
Have suitable outdoor installation space
Are replacing an existing gas storage unit
Have hot water usage that suits a storage tank

Common gas storage categories include:

Popular gas storage options include:

Instant Gas Water Heating Systems

Instant gas hot water systems heat water as it passes through the unit. They do not store a full tank of hot water.

Instant gas may suit homes that:

Want continuous flow hot water
Want a compact wall-mounted unit
Already have natural gas or LPG
Have suitable gas pipe sizing
Have suitable water pressure
Have outdoor wall space
Are replacing an existing instant gas system

Instant gas systems are commonly compared by flow rate, such as 16L, 20L and 26L.

16L Instant Gas Hot Water Systems

A 16L instant gas hot water system may suit lower-demand homes or smaller applications.

It may suit:

One-bathroom homes
Smaller households
Lower shower demand
Replacing an existing 16L unit
Properties where gas supply or water pressure does not support a larger unit

Relevant options include:

20L Instant Gas Hot Water Systems

A 20L instant gas hot water system may suit small-to-medium households with moderate hot water demand.

It may suit:

Smaller families
Moderate shower use
One-to-two bathroom homes, depending on fixtures and habits
Replacing an existing 20L unit
Homes where a 26L unit is not needed or not supported by site conditions

Relevant options include:

26L Instant Gas Hot Water Systems

A 26L instant gas hot water system is often compared for family homes and higher shower demand.

It may suit:

Larger households
Higher hot water demand
Some two-bathroom homes
Homes wanting continuous flow gas hot water
Replacing an existing 26L unit
Properties with suitable gas pipe sizing
Properties with suitable water pressure

Popular options include:

A 26L system is not automatically the best option for every home. Gas pipe sizing and water pressure must support the selected model.

Gas Storage vs Instant Gas Hot Water

System Type	How It Works	Best Suited To	Key Checks
Gas storage	Heats and stores water in a tank	Homes wanting stored hot water	Tank size, gas type, valves, drainage
Instant gas	Heats water as it flows through the unit	Homes wanting continuous flow hot water	Flow rate, gas pipe sizing, water pressure
26L instant gas	Larger continuous flow option	Some higher-demand homes	Gas supply, pipe sizing, water pressure

Gas storage may be better if your old gas storage unit worked well and your household likes a tank-style system.

Instant gas may be better if you want a compact wall-mounted system and the property supports the required flow rate.

Gas Hot Water vs Electric Hot Water

Electric hot water systems use an electric element to heat stored water. They may suit homes without gas or customers wanting a simple like-for-like electric replacement.

Gas hot water may suit homes that already have natural gas or LPG available.

Option	Best Suited To	Key Considerations
Electric storage	Homes without gas or simple electric replacements	Tank size, electrical supply, tariff, drainage
Gas storage	Homes with gas wanting stored hot water	Correct gas type, valves, outdoor location
Instant gas	Homes wanting continuous flow gas hot water	Gas pipe sizing, water pressure, gas type
Heat pump	Energy-focused electric homes	Outdoor airflow, drainage, noise, electrical supply

If your home does not have gas, electric storage or heat pump hot water may be more relevant.

Gas Hot Water vs Heat Pump Hot Water

A heat pump hot water system is an electric-style storage system that uses heat from the surrounding air to help heat water.

Heat pump hot water may suit homes that:

Are replacing older electric storage
Want to reduce hot water electricity use
Have suitable outdoor space
Have clear airflow
Can manage condensate drainage
Have suitable electrical supply
Want to use more daytime solar electricity where timing suits

Gas hot water may suit homes that:

Already have natural gas or LPG
Want gas storage or instant gas
Have suitable gas pipe sizing
Have suitable water pressure
Prefer continuous flow hot water

Neither option is automatically best. The right system depends on the home.

Installation Requirements for Gas Water Heating Systems

Gas water heating systems need correct installation to operate safely and reliably.

Before ordering, check:

Natural gas or LPG supply
Correct gas model
Existing gas pipe sizing
Water pressure
Water flow rate
Current system type
New system type
Outdoor installation location
Required clearances
Ventilation and flue requirements where applicable
Electrical requirements for ignition or controls
Existing valve condition
Drainage and overflow points
Pipework route
Access for delivery
Access for servicing
Whether old unit removal is needed
Whether disposal is included

Gas work must be completed by a licensed gas fitter.

Outdoor and Indoor Gas Hot Water Suitability

Most external gas hot water units are designed for outdoor installation.

Do not install an external gas unit indoors unless the specific model is approved for internal flued installation.

Before ordering, confirm:

Whether the model is external or internal flued
Required wall clearances
Window and door clearances
Ventilation requirements
Flue requirements where applicable
Weather exposure
Access for servicing
Gas supply route
Pipework route
Electrical connection where required

Choosing the wrong type of gas unit can create installation and compliance problems.

What Is Not Included in Supply-Only Gas Hot Water Pricing?

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

It does not usually include:

Installation labour
Licensed gas fitting
Electrical 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
Relocation of the system
Gas type conversion
Site assessment

Always check the product page and confirm site requirements with your licensed installer before ordering.

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 gas fitter or installer organised and want to order the product online.

Supply-only may suit you if:

Your installer has confirmed the correct model
The correct gas type has been selected
Gas pipe sizing has been checked
Water pressure has been checked
Outdoor location and clearances are suitable
Existing valves and drainage have been reviewed
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.

Before choosing a supplied-and-installed option, check exactly what is included and what may be extra.

Brisbane and Gold Coast Gas Hot Water Considerations

For Brisbane and Gold Coast homes, gas water heating selection often depends on the existing system, natural gas or LPG availability, outdoor space and site access.

Common local considerations include:

Natural gas vs LPG availability
Replacing gas storage with gas storage
Changing gas storage to instant gas
Replacing an old instant gas unit
Gas pipe sizing for 26L systems
Water pressure
Outdoor wall space
Clearances around windows and doors
Side access
Existing valve condition
Drainage and overflow
Old unit removal and disposal
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.

Gas Hot Water Brands to Compare

Installed Today stocks a range of major hot water brands, including:

Brand matters, but correct gas type, size, water pressure, gas pipe sizing and installation suitability matter more than brand alone.

Rheem Gas Water Heating Systems

Rheem hot water systems include electric, gas and heat pump options.

Rheem gas products to compare include:

Rinnai Gas Water Heating Systems

Rinnai hot water systems are commonly compared for instant gas hot water.

Popular Rinnai gas options include:

Bosch Gas Water Heating Systems

Bosch hot water systems are often compared for compact instant gas hot water applications.

Relevant Bosch options include:

Maintenance for Gas Water Heating Systems

Gas water heating systems need maintenance according to the manufacturer’s requirements and the installation conditions.

General maintenance considerations include:

Keeping the area around the unit clear
Checking for visible leaks
Watching for rust or corrosion
Monitoring hot water temperature
Checking for unusual noises
Checking valves where required
Keeping external units clear of debris
Following manufacturer servicing guidance
Using a licensed gas fitter for gas faults or repairs

Do not attempt gas repairs yourself.

Common Gas Hot Water Problems

A gas water heating system may need attention if you notice:

No hot water
Hot water cutting in and out
Inconsistent temperature
Pilot or ignition issues
Error codes on instant gas units
Unusual noises
Rust or corrosion
Water leaks
Poor hot water flow
Gas smell
Discoloured hot water

Gas smell or suspected gas leaks should be treated seriously. Turn off gas where safe to do so and contact a licensed gas fitter or the relevant emergency service.

Common Mistakes When Choosing a Gas Water Heating System

Ordering the Wrong Gas Type

Natural gas and LPG systems are different. Always choose the correct model.

Choosing 26L Instant Gas Without Checking Gas Pipe Sizing

A 26L unit can suit some homes, but only where gas supply and water pressure support it.

Replacing the Same System Without Checking Demand

If the old system was too small or struggled during peak use, replacing it with the same size may repeat the problem.

Installing an External Gas Unit Indoors

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

Comparing Supply-Only and Installed Pricing Incorrectly

A supply-only product price is not the same as a full installed price.

Ignoring Water Pressure

Poor water pressure can affect instant gas performance.

Choosing by Brand Alone

The right system is the one that suits the household demand and installation conditions.

Before Ordering Checklist

Before ordering a gas water heating system, confirm:

Current system type
Current system size
Whether the old system ran out of hot water
Number of people in the home
Number of bathrooms
Shower habits
Peak hot water demand
Natural gas or LPG availability
Correct gas type
Gas pipe sizing
Water pressure
Outdoor installation location
External or internal-flued suitability
Access for delivery and installation
Drainage and overflow requirements
Whether new valves may be needed
Whether electrical connection is required
Whether old unit removal is included
Whether disposal is included
Whether supply-only or supplied-and-installed is the right option
Installer confirmation before buying supply only

Frequently Asked Questions

What is a gas water heating system?

A gas water heating system uses natural gas or LPG to heat water for showers, baths, kitchens, laundries and household hot water use. It may be a storage system or an instant gas system.

Is gas hot water better than electric?

It depends on the home. Gas hot water can suit homes already set up for natural gas or LPG. Electric storage can suit homes without gas, while heat pump hot water may suit energy-focused homes with suitable outdoor space.

What is the difference between gas storage and instant gas hot water?

Gas storage systems heat and store water in a tank. Instant gas systems heat water as it flows through the unit when a hot tap is turned on.

What size gas hot water system do I need?

The right size depends on people in the home, bathrooms, shower habits, peak demand, water pressure, gas pipe sizing and whether you want storage or instant gas.

Is a 26L gas hot water system good for a family?

A 26L instant gas system can suit some family homes, but only where gas pipe sizing and water pressure support it. A licensed gas fitter should confirm suitability.

Can I use LPG with a natural gas hot water system?

No. Natural gas and LPG systems are different. Always choose the correct gas type.

Can an external gas hot water unit be installed indoors?

No. External gas units are designed for outdoor installation unless the specific manufacturer model is approved for internal flued installation.

Does gas hot water need electricity?

Some gas hot water systems need electricity for ignition, controls or operation. Check the specific model and installation requirements before ordering.

Does supply-only gas hot water pricing include installation?

No. Supply-only generally means the product only unless installation is selected or clearly shown. Installation, gas fitting, valves, electrical work, pipework, drainage, removal, disposal and compliance upgrades are usually separate.

Can I install a gas water heating system myself?

No. Gas hot water systems involve plumbing, gas fitting, water pressure, valves and compliance requirements. Gas work must be completed by a licensed gas fitter.

Final Word

A gas water heating system can be a strong choice for homes already set up for natural gas or LPG. Gas storage systems can suit households wanting stored hot water, while instant gas systems can suit homes wanting continuous flow hot water and a compact outdoor unit.

The best gas hot water system is not just the biggest or cheapest model. It is the system that matches your gas type, household demand, water pressure, gas pipe sizing, installation location and long-term needs.

Before ordering supply only through Installed Today, confirm the selected product with your licensed gas fitter or 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.

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