Best Instant Gas Hot Water Systems in Australia: Complete Buyer’s Guide

Choosing the best instant gas hot water system in Australia depends on your gas type, household size, number of bathrooms, daily hot water demand, available space and replacement setup. Instant gas, also called continuous flow gas hot water, can be a strong option for homes with natural gas or LPG that want hot water heated on demand instead of stored in a large tank.

At Hot Water Outlet, you can compare instant gas hot water systems online from trusted brands, along with the wider range of hot water systems, gas hot water systems, electric hot water systems, heat pump hot water systems and common valves, pipework and fittings.

Quick Answer: What Is the Best Instant Gas Hot Water System?

The best instant gas hot water system is the one that matches your property’s gas type, household demand, number of bathrooms, required flow rate and replacement setup.

As a general guide:

• Choose a smaller instant gas unit for lower-demand homes, small households or properties with limited simultaneous hot water use.

• Choose a medium-flow instant gas system for everyday household use where one or two outlets may be used.

• Choose a higher-flow instant gas system for larger homes, family households or properties with multiple bathrooms.

• Choose the correct natural gas or LPG model, because gas types are not interchangeable.

• Check controller options, flow rate in L/min, dimensions, connection positions and outdoor location suitability before ordering.

For most buyers, the best starting point is to compare instant gas hot water systems by gas type, flow rate, brand, household suitability and product specifications.

What Is an Instant Gas Hot Water System?

An instant gas hot water system heats water as it flows through the unit. Unlike a storage tank, it does not keep a large amount of hot water heated and ready. When a hot tap is turned on, the unit heats water on demand using natural gas or LPG.

Instant gas systems are often called:

• Continuous flow hot water systems

• Continuous flow gas hot water systems

• Instantaneous gas hot water systems

• Tankless gas hot water systems

• Instant gas water heaters

These systems are commonly compared by flow rate in L/min, gas type, controller compatibility, dimensions, connection positions and household suitability.

Instant gas hot water may suit homes where:

• Natural gas or LPG is already available

• The current hot water system is gas

• Continuous flow hot water is preferred

• A large storage tank is not ideal

• The right flow rate can be matched to household demand

• The property has a suitable outdoor location

• A licensed gas fitter can complete the connection work

Instant gas is not automatically the right option for every home. It needs to match the property’s gas supply, water demand, number of bathrooms and installation requirements.

Why Instant Gas Hot Water Systems Are Popular

Instant gas hot water systems are popular because they heat water only when needed and do not rely on a large storage tank. This can make them appealing for households that want a compact gas hot water option with continuous flow performance.

Many buyers compare instant gas hot water when:

• Replacing an old gas storage system

• Replacing an older continuous flow unit

• Renovating a bathroom, kitchen or laundry

• Moving away from a large storage tank

• Comparing gas hot water options

• Choosing a system for a family home

• Looking for a compact outdoor gas hot water unit

Instant gas systems are especially common in homes already connected to natural gas or LPG. If your home does not have gas, compare electric hot water systems and heat pump hot water systems instead.

Instant Gas vs Gas Storage Hot Water

Instant gas and gas storage hot water systems both use gas, but they work differently.

A gas storage system heats and stores hot water in a tank. An instant gas system heats water as it passes through the unit.

Choose instant gas hot water systems if you want continuous flow gas hot water and the selected flow rate suits your home. Choose gas hot water systems if you want to compare gas storage options or traditional gas tank replacements.

Instant Gas vs Electric Hot Water

Instant gas and electric storage hot water systems suit different homes.

Electric storage systems heat and store water in a tank using electricity. Instant gas systems heat water on demand using natural gas or LPG.

If your home already has gas, instant gas may be worth comparing. If your home has electric storage and no gas supply, electric hot water systems or heat pump hot water systems may be more relevant.

Natural Gas vs LPG Instant Gas Hot Water

One of the most important checks before buying an instant gas hot water system is gas type.

Natural gas and LPG systems are different. A natural gas instant gas hot water system is designed for natural gas. An LPG instant gas hot water system is designed for LPG. They are not interchangeable.

Before ordering, confirm whether the property uses:

• Natural gas

• LPG bottles

• Bulk LPG

• Existing gas storage

• Existing instant gas

• No gas supply

Do not guess the gas type. Choosing the wrong model can create delays, compatibility issues and extra costs. If you are unsure, speak with a licensed gas fitter before ordering.

What Flow Rate Instant Gas Hot Water System Do I Need?

Instant gas hot water systems are usually compared by flow rate in L/min. Flow rate describes how much hot water the unit can produce under suitable conditions.

The right flow rate depends on:

• Number of people in the home

• Number of bathrooms

• Number of showers

• Shower flow demand

• Whether multiple outlets are used at once

• Bath use

• Kitchen hot water use

• Laundry hot water use

• Gas supply

• Water pressure

• Product specifications

A small home with one bathroom may not need the same flow rate as a larger family home with two bathrooms and back-to-back showers. The goal is to choose a flow rate that suits real household demand.

16L vs 20L vs 26L Instant Gas Hot Water

Many buyers compare 16 L/min, 20 L/min and 26 L/min instant gas hot water systems. These are common flow rate categories, but the right choice depends on the property.

A higher flow rate can support more demand, but bigger is not always automatically better. The system still needs to suit the gas supply, household use and product requirements.

Best Instant Gas Hot Water System for Small Homes

Small homes, units and townhouses may suit a lower to medium flow instant gas system, depending on usage. The key is to match the unit to the number of people, number of bathrooms and how often hot water is used at the same time.

For smaller homes, compare:

• Natural gas or LPG model

• Flow rate in L/min

• Number of occupants

• Number of bathrooms

• Shower use

• Kitchen and laundry hot water demand

• Available wall space

• Connection positions

• Product dimensions

A small household should not automatically choose the smallest system. If hot water use is high or multiple outlets are used at once, a larger flow rate may be worth comparing.

Best Instant Gas Hot Water System for Families

Family homes usually need stronger hot water performance than smaller households. A family may need a higher-flow instant gas system, especially if multiple showers, bathrooms or hot water outlets are used close together.

For family homes, compare:

• Number of people in the home

• Number of bathrooms

• Morning and evening shower demand

• Back-to-back showers

• Bath use

• Laundry use

• Kitchen use

• Whether multiple outlets run at once

• Gas type

• Flow rate in L/min

An instant gas system can suit family homes when the flow rate is matched correctly. A family of four with one bathroom may have very different needs from a family of five with two bathrooms and frequent simultaneous hot water use.

Best Instant Gas Hot Water System for Rental Properties

For rental properties, the best instant gas hot water system is usually one that suits the existing gas supply, property size, likely tenant demand and replacement setup.

For rentals, compare:

• Existing gas type

• Current hot water system type

• Current flow rate if replacing instant gas

• Current tank size if replacing gas storage

• Number of bedrooms

• Number of bathrooms

• Likely tenant demand

• Brand recognition

• Warranty information

• Product availability

• Required valves and fittings

• Delivery access

A like-for-like instant gas replacement may be practical if the current system worked well. If tenants have reported poor hot water performance, compare whether a different flow rate or system type is needed.

Best Instant Gas Hot Water System for Renovations

Renovations are a good time to review the hot water system. A new bathroom, larger bath, upgraded kitchen or laundry renovation can change how much hot water the property needs.

Instant gas may suit a renovation if:

• The home already has natural gas or LPG

• Continuous flow hot water is preferred

• A storage tank is being removed

• The new layout increases hot water demand

• The system location can be planned properly

• The flow rate suits the finished home

For renovation projects, think about the final layout, not just the current household demand. If you are adding another bathroom, upgrading fixtures or changing the kitchen/laundry layout, check whether the selected system will still suit after the renovation is complete.

You may also need valves, pipework and fittings depending on the replacement and renovation setup.

Best Instant Gas Hot Water System for Like-for-Like Replacement

If your old instant gas hot water system has failed, is unreliable or no longer keeping up, a like-for-like replacement may be the simplest place to start.

Before ordering, check:

• Existing brand and model

• Natural gas or LPG

• Current flow rate in L/min

• Existing controller setup

• Current dimensions

• Connection positions

• Outdoor location

• Water pressure

• Power requirements

• Required valves and fittings

• Delivery access

If the current system supplied enough hot water, a similar flow rate may be a practical starting point. If the old unit struggled, compare whether a higher flow rate or different model may better suit the household.

Best Instant Gas Hot Water System for Replacing Gas Storage

Some homes compare instant gas when replacing an old gas storage hot water system. Moving from gas storage to instant gas may appeal if you want continuous flow hot water and no large storage tank.

Before replacing gas storage with instant gas, check:

• Current gas type

• Current gas storage tank size

• Existing gas supply

• Existing unit location

• Available wall space

• Flow rate required

• Number of bathrooms

• Household demand

• Connection changes

• Required valves and fittings

• Licensed gas fitting requirements

A gas storage system and instant gas system do not connect or perform in exactly the same way. Suitability should be checked before ordering.

Instant Gas Hot Water Brands to Compare

Hot Water Outlet lists recognised hot water brands so buyers can compare instant gas systems by flow rate, gas type, controller options and product specifications.

Rinnai Instant Gas Hot Water Systems

Rinnai hot water systems are commonly compared by buyers looking at instant gas and continuous flow hot water. Rinnai may be worth reviewing if you want to compare different flow rates, gas types and controller options.

When comparing Rinnai instant gas systems, check the natural gas or LPG model, flow rate in L/min, controller compatibility, dimensions and warranty information.

Rheem Instant Gas Hot Water Systems

Rheem hot water systems are widely recognised across gas, electric, instant gas and heat pump categories. Rheem may be worth comparing if you want a familiar brand with a broad hot water range.

When comparing Rheem instant gas systems, check gas type, flow rate, household suitability, connection positions and product specifications.

Bosch Instant Gas Hot Water Systems

Bosch hot water systems are often compared by buyers looking at gas and continuous flow hot water systems.

When comparing Bosch instant gas systems, check natural gas or LPG suitability, flow rate, controller options, dimensions and installation requirements.

Dux Instant Gas Hot Water Systems

Dux hot water systems are commonly considered across household hot water categories. Dux may be worth comparing if you are reviewing multiple gas and storage hot water options.

When comparing Dux gas hot water products, check system type, gas type, flow rate or tank capacity, dimensions and warranty information.

Instant Gas Hot Water Replacement Guide

Replacing an instant gas hot water system starts with identifying the current model and setup. This makes it easier to compare a suitable replacement.

Look for:

• Brand

• Model number

• Flow rate

• Natural gas or LPG

• Controller setup

• Existing location

• Connection positions

• Dimensions

• Power requirements

• Manufacturing date

• Water pressure rating

If the current unit has worked well, a similar flow rate and gas type may be a good starting point. If the current unit has not kept up with household demand, compare whether a higher-flow model may be more suitable.

When Should You Replace an Instant Gas Hot Water System?

You may need to consider replacing an instant gas hot water system if:

• Hot water temperature is unreliable

• The unit is old and unreliable

• The system no longer suits household demand

• Error codes are recurring

• Repairs are becoming uneconomical

• The unit does not keep up with multiple outlets

• The current system is the wrong size for the home

• You are renovating and changing hot water demand

• You want to upgrade from an older continuous flow model

• A licensed tradesperson has recommended replacement

Not every hot water issue means the full system needs replacement. Some problems may relate to controllers, valves, gas supply, water flow or other components. If you are unsure, speak with a licensed plumber or gas fitter before ordering.

Instant Gas Hot Water Controllers

Some instant gas hot water systems may support temperature controllers. Controllers can allow temperature control from selected areas of the home, depending on the system and setup.

Before choosing a system based on controllers, check:

• Whether the unit supports controllers

• Which controller models are compatible

• How many controllers can be used

• Where controllers may be located

• Whether your current controllers are compatible

• Whether extra wiring or accessories are required

Do not assume controllers are included or compatible. Always check the product listing and specifications before ordering.

Instant Gas Hot Water Parts and Accessories

An instant gas hot water order may need more than the main unit. Depending on the replacement setup, pressure requirements, connection layout and controller requirements, extra parts may be needed.

Common items to check include:

• Tempering valves

• Pressure relief valves

• Duo valves

• Non-return valves

• Isolation valves

• Controller accessories

• Copper pipework

• Fittings

• Connection accessories

Hot Water Outlet has a dedicated range of valves, pipework and fittings to help customers compare common hot water accessories.

Always confirm compatibility before ordering. Gas and plumbing work should be completed by appropriately licensed tradespeople.

Instant Gas Hot Water Pros and Cons

Potential Advantages of Instant Gas Hot Water

Instant gas hot water can be a practical choice for homes already using natural gas or LPG.

Potential advantages include:

• Continuous flow hot water when correctly sized

• No large storage tank

• Compact wall-mounted design

• Natural gas and LPG options available

• Common choice for gas hot water replacements

• Available from recognised brands

• Flow rates available for different household sizes

• Can suit homes, rentals and renovation projects

Potential Disadvantages of Instant Gas Hot Water

Instant gas is not right for every property.

Potential disadvantages include:

• Requires natural gas or LPG

• Correct gas type must be selected

• Flow rate must suit household demand

• Gas supply must be suitable

• Controllers may be optional or model-specific

• Connection positions must be checked

• Gas and plumbing work must be completed by licensed tradespeople

• Some homes may be better suited to storage, electric or heat pump systems

The best way to compare instant gas hot water is to look at the whole property, not just the purchase price.

What to Check Before Buying an Instant Gas Hot Water System

1. Gas Type

Confirm whether the property uses natural gas or LPG. This is one of the most important checks before ordering.

2. Flow Rate

Choose a flow rate in L/min that suits the number of bathrooms, occupants and hot water outlets.

3. Number of Bathrooms

Homes with multiple bathrooms may need a higher-flow system than smaller one-bathroom homes.

4. Simultaneous Use

Think about whether showers, kitchen taps and laundry use happen at the same time.

5. Existing System

Check the current brand, model, gas type and flow rate before choosing a replacement.

6. Controller Options

If you want temperature controllers, check compatibility before ordering.

7. Dimensions

Compare the product dimensions with the available wall space.

8. Connection Positions

Check water, gas and power connection positions against the existing setup.

9. Outdoor Location

Many instant gas systems are external units. Check whether the selected product suits the intended location.

10. Required Valves and Fittings

Check whether the order needs valves, fittings or pipework as well as the main system.

Common Mistakes When Buying Instant Gas Hot Water

Choosing the Wrong Gas Type

Natural gas and LPG systems are not interchangeable. Always confirm the property gas type before ordering.

Buying by Price Alone

A cheaper instant gas unit is not good value if it does not suit the home, flow rate needs or gas supply.

Choosing Too Low a Flow Rate

An undersized instant gas system may struggle when multiple outlets are used or when household demand is high.

Assuming Bigger Is Always Better

A higher-flow system may not be necessary for every home. Choose based on actual demand, gas supply and product suitability.

Forgetting Controller Compatibility

Not every controller works with every unit. If controllers matter, check compatibility before ordering.

Ignoring Connection Positions

Connection positions can vary between models. Compare the new unit with the current setup before ordering.

Forgetting Valves and Fittings

Some replacements may require compatible valves, pipework or fittings. Check the full order, not just the main unit.

Trying to DIY Gas Work

Gas work must be completed by licensed tradespeople. Do not attempt gas connection work yourself.

Instant Gas Hot Water Buyer Checklist

Before ordering an instant gas hot water system online, check:

• Natural gas or LPG

• Current system type

• Current brand and model

• Current flow rate

• Household size

• Number of bathrooms

• Shower demand

• Bath use

• Kitchen hot water use

• Laundry hot water use

• Simultaneous outlet use

• Required flow rate in L/min

• Controller requirements

• Dimensions

• Connection positions

• Outdoor location suitability

• Water pressure

• Gas supply suitability

• Required valves

• Required fittings

• Delivery access

• Warranty information

• Product specifications

Are Instant Gas Hot Water Systems Worth It?

Instant gas hot water systems can be worth it when the home already has natural gas or LPG and the selected flow rate suits household demand. They can be especially appealing for homes wanting continuous flow hot water without a large storage tank.

Instant gas may be a good fit if:

• The home already uses gas

• The correct gas type is known

• A compact wall-mounted unit is preferred

• The household wants continuous flow hot water

• The selected flow rate suits the number of bathrooms

• The existing setup can support the replacement

• Licensed gas fitting and plumbing work can be completed

If the home does not have gas, compare electric hot water systems, heat pump hot water systems or the full hot water systems range instead.

Compare Instant Gas Hot Water Systems Online

Hot Water Outlet makes it easier to compare instant gas hot water systems online by gas type, flow rate, brand, controller options, household suitability and product specifications.

Start with:

• Instant Gas Hot Water Systems

• Gas Hot Water Systems

• Hot Water Systems

• Valves, Pipework and Fittings

If you are still deciding between system types, compare instant gas against electric hot water systems and heat pump hot water systems as well.

FAQs About Instant Gas Hot Water Systems

What is the best instant gas hot water system in Australia?

The best instant gas hot water system is the one that suits your gas type, household size, number of bathrooms, flow rate needs and replacement setup. Compare natural gas and LPG models, flow rate in L/min, controller options, dimensions and product specifications before ordering.

What size instant gas hot water system do I need?

Instant gas systems are sized by flow rate in L/min. Smaller homes may suit lower-flow systems, while larger homes or properties with multiple bathrooms may need a higher-flow model. The right size depends on real household demand.

Is 16L instant gas hot water enough?

A 16 L/min instant gas system may suit smaller households or lower-demand homes, but it may not suit larger families or homes where multiple hot water outlets are used at the same time. Check the number of bathrooms, occupants and usage pattern before ordering.

Is 20L instant gas hot water enough?

A 20 L/min instant gas system may suit moderate household demand, depending on the number of bathrooms, shower use and simultaneous hot water use. Always compare the flow rate against your actual household needs.

Is 26L instant gas hot water enough for a family?

A 26 L/min instant gas system is commonly compared for larger homes and families with higher hot water demand. Suitability still depends on gas type, gas supply, number of bathrooms and how hot water is used in the home.

Is instant gas better than gas storage hot water?

Instant gas and gas storage suit different homes. Instant gas heats water on demand and does not require a large storage tank. Gas storage keeps heated water in a tank. The better option depends on your current setup, household demand, available space and replacement goals.

Can I replace gas storage with instant gas hot water?

Some homes may be able to replace gas storage with instant gas, but suitability depends on gas type, gas supply, location, flow rate requirements and connection changes. Speak with a licensed gas fitter if you are unsure.

Can I replace an old instant gas unit with the same size?

You may be able to replace an old instant gas unit with a similar flow rate if the current system worked well and household demand has not changed. If the old unit struggled, compare whether a higher-flow model may be more suitable.

What is the difference between natural gas and LPG instant gas hot water?

Natural gas and LPG are different gas types. A natural gas instant gas unit is designed for natural gas, while an LPG model is designed for LPG. They are not interchangeable.

Do instant gas hot water systems need controllers?

Some instant gas systems may support temperature controllers, but controllers are model-specific and may not be included. Check compatibility before ordering.

Do instant gas hot water systems need valves and fittings?

Some instant gas replacements may require valves, pipework or fittings depending on the system, pressure requirements and connection layout. Browse valves, pipework and fittings and confirm compatibility before ordering.

Can I install an instant gas hot water system myself?

No. Instant gas hot water systems involve gas and plumbing work that must be completed by appropriately licensed tradespeople. Hot Water Outlet sells supply-only hot water systems and accessories online, and may help organise quotes from reputable installers where appropriate.

Find the Best Instant Gas Hot Water System for Your Home

The best instant gas hot water system is the one that suits your gas type, flow rate needs, household demand, available space and replacement setup. Before ordering, compare natural gas and LPG models, flow rate in L/min, controller options, dimensions, connection positions, warranty information and required accessories.

Browse instant gas hot water systems online with Hot Water Outlet to compare trusted brands, or explore the full hot water systems range if you are still deciding between gas, electric, heat pump and storage options.