2024 Best Instant Gas Hot Water Systems

Choosing the best instant gas hot water system in 2024 comes down to more than picking the biggest unit or the most recognisable brand.

The right system depends on your household size, number of bathrooms, gas supply, water pressure, installation location, hot water habits and whether you are replacing an existing gas unit or changing from electric storage, gas storage or solar hot water.

For many Brisbane, Gold Coast and South East Queensland homes, instant gas hot water is popular because it provides continuous hot water on demand without needing a large storage tank. But it is not the right solution for every property.

This guide compares the top instant gas hot water system options for 2024, explains what matters when choosing a unit, and helps you decide whether brands like Rinnai, Rheem, Dux, AquaMAX, Bosch, Vulcan or Thermann are the right fit for your home.

Quick answer

The best instant gas hot water system for most homes in 2024 is usually a quality 6-star continuous flow unit from a proven brand such as Rinnai or Rheem, sized correctly for the number of bathrooms and hot water outlets in the home.

For many households, the Rinnai B-Series, Rheem Metro Series and Rinnai Infinity range are strong options because they balance efficiency, reliability, availability and brand support. However, the best system for your home depends on gas supply, flow rate, installation location, water temperature requirements and household demand.

If you are replacing or upgrading a gas hot water system, JR Gas & Water can help compare instant gas hot water systems, gas storage hot water systems, hot water repairs and servicing, and other hot water system options.

What is an instant gas hot water system?

An instant gas hot water system, also called a continuous flow gas hot water system, heats water only when a hot tap is turned on.

Instead of storing hot water in a tank, the unit detects water flow, lights the gas burner and heats water as it passes through the heat exchanger. This means the system does not run out of stored hot water in the same way a tank can.

Instant gas hot water can suit:

• homes with natural gas or LPG

• households wanting continuous hot water

• homes with limited space for a tank

• replacements for older continuous flow systems

• some replacements for gas storage systems

• households with steady hot water demand

• homes where wall-mounted external installation is practical

It may not suit:

• homes without suitable gas supply

• properties with undersized gas pipework

• homes with very low water pressure

• households wanting to reduce gas use

• properties better suited to a heat pump

• complex internal installation situations

• homes where the unit is too far from bathrooms or kitchens

Instant gas is excellent for the right property, but it still needs to be sized and installed correctly.

Best instant gas hot water systems for 2024

Best Overall: Rinnai B-Series

The Rinnai B-Series earns the top spot as one of the strongest instant gas hot water choices for 2024 because it offers a practical balance of price, performance, reliability and brand support.

It is a popular option for homeowners who want continuous hot water without jumping into the highest-priced models.

Best for

• standard family homes

• replacing older continuous flow systems

• customers wanting strong value

• natural gas or LPG homes

• homeowners wanting a proven brand

• households wanting a simple, efficient instant gas option

Why it ranks highly

The Rinnai B-Series is widely considered a strong all-rounder because it gives many homes the main benefits of instant gas hot water without overcomplicating the choice.

It offers continuous hot water, compact wall-mounted design, good energy efficiency and strong brand recognition. It is also a practical fit for many external replacement jobs where the home already has a compatible gas setup.

Things to consider

Some B-Series models may not have the same premium display or advanced features as higher-end units. For many households, that will not matter. But if you want advanced controls, premium features or a very specific flow rate setup, it is worth comparing the broader instant gas hot water range.

Reliable Runner-Up: Rheem Metro Series

The Rheem Metro Series is another strong 2024 option, especially for customers who like the security of a well-known Australian hot water brand.

Rheem has a long-standing reputation in hot water, and the Metro range is commonly considered by homeowners comparing reliable continuous flow gas systems.

Best for

• homes wanting a trusted hot water brand

• customers comparing Rinnai and Rheem

• standard external gas hot water replacements

• households wanting 6-star continuous flow efficiency

• homeowners who value after-sales support

Why it ranks highly

The Rheem Metro range is a good fit for homeowners who want a mainstream, proven instant gas system with strong brand backing.

It is especially worth considering if you already have a Rheem gas hot water system and want to stay with the same brand or if your installer recommends it based on the site conditions.

Things to consider

The best Rheem Metro model depends on flow rate requirements and household demand. A smaller model may suit a single-bathroom home, while a larger one may be needed for multiple bathrooms or higher simultaneous hot water use.

Best Premium Continuous Flow Option: Rinnai Infinity Series

The Rinnai Infinity Series is one of the better-known premium names in continuous flow gas hot water.

It is commonly chosen by homeowners who want a higher-end instant gas unit, strong performance and a brand with a long history in continuous flow systems.

Best for

• homeowners wanting a premium continuous flow unit

• larger households with suitable gas supply

• homes with multiple hot water outlets

• customers who value brand reputation

• homes where system performance matters more than lowest upfront price

Why it ranks highly

The Rinnai Infinity range has a strong reputation because it helped define the continuous flow gas hot water category in Australia.

For the right home, it can provide dependable continuous hot water and strong performance. It is particularly worth considering when the household wants a premium gas hot water replacement and the site has suitable gas supply and installation conditions.

Things to consider

A premium system still needs correct sizing. If the gas pipework, water pressure or installation location is not suitable, even a premium unit may not perform properly.

Best Budget-Friendly Instant Gas Options

Not every home needs the highest-priced instant gas system. For some households, a more affordable continuous flow model may be the better value choice.

Brands such as Dux, Thermann, Vulcan and other mainstream options may suit homeowners looking for a practical gas hot water replacement at a lower upfront cost.

Best for

• rental properties

• straightforward replacements

• budget-conscious homeowners

• smaller homes

• households with moderate hot water use

• customers who want instant gas without premium pricing

What to consider

Budget-friendly does not mean bad. But it does mean you should pay attention to warranty, parts availability, service support, heat exchanger quality, noise, flow rate and installation suitability.

A cheaper unit is not good value if it is undersized, difficult to service or poorly matched to the home.

Best Instant Gas System for Larger Homes

For larger homes, the main issue is not just brand. It is flow rate.

A larger household may need a 26L, 27L or higher-capacity continuous flow unit depending on the number of bathrooms, simultaneous hot water use and incoming water temperature.

Best for

• homes with 2 or more bathrooms

• families with high shower demand

• homes where two outlets may run at once

• larger houses with suitable gas pipe sizing

• customers wanting continuous hot water rather than storage

What to consider

For larger homes, the gas supply is critical. A high-flow instant gas unit may require adequate gas pipe sizing and supply capacity. If the existing gas line is undersized, the unit may not perform properly or the installation may require additional gas fitting work.

Before choosing a large instant gas system, confirm:

• number of bathrooms

• number of people in the home

• gas type

• existing gas pipe sizing

• water pressure

• distance to fixtures

• whether multiple hot water outlets run together

• whether controllers are required

Best Instant Gas Alternative: Gas Storage Hot Water

Instant gas is not always the best answer.

Some households may be better suited to a gas storage hot water system, especially if they already have a storage system and want a simpler like-for-like replacement.

Gas storage may suit if:

• the home already has outdoor gas storage

• the household prefers stored hot water

• the existing location suits a direct replacement

• the gas line is not suitable for a high-flow continuous unit

• upfront cost matters

• the home has moderate hot water demand

Instant gas may suit if:

• you want continuous hot water

• space is limited

• a wall-mounted system is preferred

• the gas supply is suitable

• the household wants to avoid stored hot water running out

• the current continuous flow system is due for replacement

If your old gas storage system has failed, compare both options before replacing it automatically.

Best Instant Gas Alternative for Efficiency: Heat Pump Hot Water

For some homes, the best upgrade may not be gas at all.

A heat pump hot water system can be a strong option for homeowners focused on energy efficiency and reducing gas use.

Heat pump hot water may suit if:

• you are replacing an old electric system

• you want to reduce running costs

• the home has suitable outdoor space

• you have solar PV

• you want a stored but efficient hot water option

• you are not locked into gas

Instant gas may suit if:

• the home already has suitable gas supply

• you want continuous hot water

• you prefer gas hot water performance

• the existing instant gas system is a straightforward replacement

• upfront cost is a priority

Both systems can be good. The right choice depends on the home.

Key features to compare before buying

1. Flow rate

Flow rate is one of the most important instant gas hot water features.

It is usually measured in litres per minute. Common residential units are often around 16L/min, 20L/min, 24L/min, 26L/min or higher depending on the model.

General guide

• 16L/min may suit smaller homes or single-bathroom properties

• 20L/min may suit smaller to medium homes

• 24L/min to 26L/min may suit many family homes

• Larger models may suit higher-demand households where gas supply allows

The right flow rate depends on how many fixtures may run at once.

2. Gas type

Instant gas systems are usually available in natural gas or LPG models.

Before ordering, confirm whether the property uses:

• natural gas

• LPG bottles

• another existing gas setup

Natural gas and LPG units are not interchangeable without the correct model or approved conversion process.

3. External vs internal installation

Many instant gas hot water systems are installed externally. Internal gas hot water installations have stricter flueing and ventilation requirements and need to be assessed carefully.

External units may suit:

• outdoor wall-mounted replacements

• existing external continuous flow systems

• homes with suitable wall space and clearances

Internal units may require:

• correct flueing

• proper ventilation

• suitable clearances

• model-specific approval

• a more detailed quote

If the current unit is internal, do not assume a standard external replacement package will apply.

4. Temperature control

Some homes need temperature controllers or specific temperature-limited models.

This can matter for:

• bathroom safety

• family homes

• rental properties

• kitchen temperature needs

• compliance requirements

• user convenience

Ask whether the selected system is temperature-limited and whether controllers are required for your setup.

5. Heat exchanger quality

The heat exchanger is one of the most important parts of an instant gas hot water system.

A good heat exchanger helps transfer heat efficiently from the burner to the water and plays a major role in performance and lifespan.

When comparing systems, consider:

• heat exchanger material

• warranty

• brand reputation

• serviceability

• parts support

• water quality issues

• maintenance expectations

6. Warranty and service support

A hot water system is not just a purchase. It is a long-term installed product.

Before choosing a system, compare:

• parts warranty

• heat exchanger warranty

• labour warranty terms

• local service support

• brand reputation

• installer support

• availability of replacement parts

This is where major brands like Rinnai and Rheem often remain popular.

7. Installation cost and site suitability

The cheapest unit may not give the cheapest installed outcome.

Installation cost can change depending on:

• existing system type

• gas pipe sizing

• unit location

• wall mounting

• water pipe alterations

• electrical requirements

• controllers

• flueing

• LPG setup

• access

• removal of the old system

• compliance upgrades

For non-standard jobs, use JR Gas & Water’s Request Quote page rather than guessing.

Brisbane and Gold Coast installation considerations

Instant gas hot water can work very well across Brisbane, Logan, Ipswich, Redlands, Moreton Bay and the Gold Coast, but local installation conditions vary.

Common local factors include:

• older homes with undersized gas pipework

• rental properties with ageing gas storage systems

• Queenslanders and post-war homes with longer pipe runs

• townhouses with tight external wall space

• properties using LPG bottles

• homes converting from electric storage

• coastal corrosion around Gold Coast properties

• long distances between the hot water unit and bathrooms

• high-demand family homes with multiple bathrooms

A good instant gas installation is not just about mounting the unit. It is about making sure the system can actually deliver the hot water the household expects.

What can go wrong if the wrong unit is chosen?

Choosing the wrong instant gas system can lead to frustrating performance issues.

Common problems include:

• water not getting hot enough

• temperature fluctuations

• poor flow at showers

• the unit cutting in and out

• poor performance when two outlets run together

• long wait times for hot water

• gas supply problems

• error codes

• unhappy tenants or family members

• higher installation costs than expected

Many of these issues can be avoided by checking household demand, gas supply, unit location and installation requirements before ordering.

What you can check before booking

Before asking for a quote, gather the following information.

Helpful details include:

• photos of the current hot water system

• model number of the existing unit

• gas type: natural gas or LPG

• number of bathrooms

• number of people in the home

• whether hot water runs out or fluctuates

• whether the unit is internal or external

• whether multiple showers run at once

• distance from the unit to bathrooms

• whether you want controllers

• suburb and property type

• access photos

This helps JR Gas & Water recommend the right system and quote more accurately.

Cost factors for instant gas hot water systems

The installed cost of an instant gas hot water system depends on the unit and the work required.

Cost can be affected by:

• brand and model selected

• flow rate

• natural gas or LPG

• external or internal installation

• whether it is a like-for-like replacement

• gas pipe sizing

• water pipe alterations

• controller installation

• flueing requirements

• electrical requirements

• old unit removal

• access to the installation area

• compliance upgrades

• urgency of replacement

For clear pricing pathways, start with JR Gas & Water’s service work pricing, browse instant gas hot water systems, or request a quote for non-standard installations.

Maintenance tips for instant gas hot water systems

Instant gas hot water systems still need basic maintenance to keep them working properly.

Good maintenance includes:

• keeping the area around the unit clear

• checking for visible corrosion or damage

• watching for error codes

• checking that the unit lights reliably

• arranging professional servicing when needed

• not ignoring fluctuating temperatures

• keeping vents and clearances unobstructed

• checking controllers for faults

• having gas-related issues checked by a licensed gas fitter

Do not open, modify or attempt to repair gas components yourself. Gas work should always be handled by a licensed gas fitter.

When to repair instead of replace

Replacement is not always necessary.

Repair may make sense if:

• the unit is relatively new

• the issue is minor

• parts are available

• the fault is isolated

• the system still suits the household

• the repair cost is reasonable

Replacement may make sense if:

• the unit is old

• faults keep returning

• parts are hard to source

• the system is undersized

• the unit is corroded

• there are repeated error codes

• the household has outgrown the system

• changing system type makes more sense

JR Gas & Water can help with hot water repairs and servicing or replacement advice if the system is no longer worth repairing.

What JR Gas & Water can help with

JR Gas & Water helps homeowners, landlords, property managers and businesses compare, repair, replace and install hot water systems across Brisbane, the Gold Coast and nearby South East Queensland areas.

Depending on the job, JR Gas & Water can help with:

• instant gas hot water systems

• gas storage hot water systems

• hot water repairs and servicing

• electric hot water systems

• heat pump hot water systems

• solar hot water systems

• gas fitting

• gas pipe sizing checks

• LPG and natural gas system selection

• replacement advice from photos and model numbers

• custom quotes for non-standard installations

Related JR Gas & Water services

• Instant Gas Hot Water Systems

• Gas Storage Hot Water Systems

• Hot Water Repairs and Servicing

• Heat Pump Hot Water Systems

• Electric Hot Water Systems

• Solar Hot Water Systems

• Gas Fitting

• Service Work Pricing

• Request a Quote

FAQs

What is the best instant gas hot water system in 2024?

For many homes, the best instant gas hot water system in 2024 is a correctly sized Rinnai or Rheem continuous flow unit. The Rinnai B-Series, Rheem Metro Series and Rinnai Infinity range are all strong options depending on household size, budget and installation requirements.

The best unit is not always the biggest or most expensive. It must suit your gas supply, number of bathrooms, flow rate requirements and installation location.

Is Rinnai or Rheem better for instant gas hot water?

Both Rinnai and Rheem make popular instant gas hot water systems. Rinnai is often strongly associated with continuous flow gas systems, while Rheem has a long-standing reputation across many hot water categories.

The better choice depends on the specific model, warranty, price, household demand, installer recommendation and site conditions.

What size instant gas hot water system do I need?

Smaller homes may only need a lower-flow unit, while family homes often need a 24L/min to 26L/min system or larger, depending on how many bathrooms and hot water outlets may run at the same time.

The correct size depends on water pressure, gas supply, distance to fixtures, number of occupants and peak hot water demand.

Can instant gas hot water run two showers at once?

Some systems can, but only if the unit has enough flow capacity and the gas supply can support it.

For two showers running at once, you will usually need a larger continuous flow system and suitable gas pipe sizing. The exact recommendation should be checked before installation.

Is instant gas better than gas storage?

Instant gas can be better if you want continuous hot water, compact wall-mounted installation and no stored tank. Gas storage can be better if you want a simpler like-for-like replacement and your existing setup already suits storage gas.

The right choice depends on the property, budget, gas supply and household usage.

Is instant gas hot water cheaper to run than electric storage?

Instant gas hot water can be cheaper to run than older electric storage systems in some homes, but the result depends on gas prices, electricity prices, usage habits, system efficiency and installation costs.

For customers focused mainly on running costs, it is also worth comparing heat pump hot water systems.

Can I install an instant gas hot water system myself?

No. Gas hot water installation must be completed by a licensed professional.

Instant gas systems involve gas, water, combustion, clearances and sometimes electrical or controller work. Incorrect installation can be unsafe and may cause performance problems.

Need help choosing the best instant gas hot water system?

If you are replacing an old gas hot water system or comparing instant gas options for your home, JR Gas & Water can help you choose a system that suits your household, gas supply, budget and installation location.

Browse the instant gas hot water system range, compare other hot water systems, or send photos and model details through for a custom recommendation.

Request a quote from JR Gas & Water