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

Choosing the best instant gas hot water system brand depends on your home’s gas type, household demand, number of bathrooms, water pressure, gas supply, available wall space and required flow rate in L/min. The best brand is not simply the cheapest or most familiar name. It is the brand with a model that suits your property, gas setup and hot water usage.

At Hot Water Outlet, you can compare instant gas hot water systems, gas hot water systems, hot water systems and leading brands including Rinnai, Bosch and Rheem.

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

There is no single best instant gas hot water brand for every home. Rinnai, Bosch and Rheem are commonly compared for instant gas and continuous flow hot water systems. The best choice depends on natural gas or LPG, required flow rate, gas supply, water pressure, bathroom count, controller compatibility, available location and product specifications.

As a general guide:

• Choose Rinnai hot water systems if you are comparing a widely searched instant gas and continuous flow hot water brand.

• Choose Bosch hot water systems if you are comparing gas continuous flow options and compact external gas hot water systems.

• Choose Rheem hot water systems if you want to compare instant gas alongside broader electric, gas storage and heat pump hot water options.

The best instant gas brand is the one with the right gas type, L/min flow rate and specifications for your home.

Instant Gas Hot Water Brands Compared

Instant gas systems are sized by flow rate in L/min, not by storage tank capacity. A higher-flow model may suit larger households, but only if the property has suitable gas supply and water pressure.

What Is an Instant Gas Hot Water System?

An instant gas hot water system heats water as it passes through the unit. It does not store hot water in a large tank.

Instant gas systems are also commonly called:

• Continuous flow hot water systems

• Gas continuous flow systems

• Tankless gas hot water systems

• Instantaneous gas hot water systems

They may suit homes that want continuous hot water from a compact external unit, provided the gas supply, water pressure and location are suitable.

Instant Gas vs Gas Storage

Instant gas and gas storage systems work differently.

An instant gas system:

• Heats water as it flows through the unit

• Is sized by flow rate in L/min

• Does not store a large tank of hot water

• Needs suitable gas supply and water pressure

• Is commonly installed externally unless the specific product is designed and approved otherwise

A gas storage system:

• Stores hot water in a tank

• Is sized by tank capacity and recovery rate

• May suit homes replacing existing tank-style gas systems

• Needs the correct natural gas or LPG model

• Takes up more physical tank space

If you want continuous flow hot water, compare instant gas hot water systems. If you want tank-style gas hot water, compare gas hot water systems.

Natural Gas vs LPG Instant Gas Systems

Before comparing instant gas brands, confirm your gas type.

Instant gas hot water systems may be:

• Natural gas

• LPG

Natural gas and LPG are not interchangeable. A natural gas model cannot simply be used on LPG unless the specific product is designed and approved for that gas type.

Before ordering, check:

• Existing hot water unit label

• Gas meter

• LPG bottle setup

• Product listing

• Appliance data plate

• Licensed gas fitter advice if unsure

Choosing the wrong gas type can cause delays, extra costs and compatibility issues.

Rinnai Instant Gas Hot Water Systems

Rinnai is one of the most searched brands for instant gas and continuous flow hot water.

Rinnai hot water systems may suit buyers who want:

• Instant gas hot water

• Continuous flow hot water

• Natural gas or LPG options where available

• A compact external gas hot water system

• A brand commonly compared against Bosch and Rheem

• Flow rate options for different household sizes

Before choosing Rinnai instant gas, check:

• Natural gas or LPG

• Required flow rate in L/min

• Number of people in the home

• Number of bathrooms

• Whether two showers may run close together

• Gas supply capacity

• Water pressure and flow

• External wall location

• Controller compatibility where relevant

• Product dimensions

• Required valves and fittings

Rinnai may suit homes where gas supply, water pressure and external location are suitable.

Bosch Instant Gas Hot Water Systems

Bosch is commonly compared for gas continuous flow and instant gas hot water.

Bosch hot water systems may suit buyers who want:

• Instant gas hot water

• Continuous flow hot water

• Natural gas or LPG options where available

• Compact external gas hot water

• A comparison against Rinnai and Rheem gas systems

Before choosing Bosch instant gas, check:

• Gas type

• Flow rate in L/min

• Gas supply suitability

• Water pressure and flow

• Number of people in the home

• Number of bathrooms

• External wall location

• Product dimensions

• Required valves and fittings

Bosch is often best compared within the instant gas category rather than against electric storage or heat pump systems.

Rheem Instant Gas Hot Water Systems

Rheem is commonly compared across several hot water categories, including instant gas, gas storage, electric storage and heat pump hot water.

Rheem hot water systems may suit buyers who want:

• Instant gas hot water

• A broader hot water brand comparison

• Natural gas or LPG options where available

• A comparison against Rinnai and Bosch

• The option to compare instant gas against storage, electric or heat pump systems

Before choosing Rheem instant gas, check:

• Natural gas or LPG

• Required L/min flow rate

• Gas supply capacity

• Water pressure and flow

• Number of bathrooms

• Product dimensions

• Connection positions

• Controller compatibility where relevant

• Required valves and fittings

Rheem may be a strong comparison brand if you are still deciding between instant gas and other hot water system types.

Rinnai vs Bosch Instant Gas

Rinnai and Bosch are both commonly compared for instant gas hot water.

Rinnai may suit buyers who:

• Are replacing an existing Rinnai system

• Want to compare Rinnai continuous flow options

• Need natural gas or LPG where available

• Want to compare controller-compatible models where relevant

• Have suitable gas supply and water pressure

Bosch may suit buyers who:

• Are replacing an existing Bosch system

• Want to compare gas continuous flow options

• Need a compact external gas hot water system

• Have suitable gas type, gas supply and water pressure

The better choice depends on the exact model, flow rate, gas type, dimensions, controller requirements and product specifications.

Rinnai vs Rheem Instant Gas

Rinnai and Rheem are both commonly compared for instant gas hot water.

Rinnai is often searched by buyers focused specifically on continuous flow gas hot water.

Rheem may suit buyers who want to compare instant gas against a broader range of hot water system types, including electric, gas storage and heat pump options.

Choose based on:

• Correct gas type

• Flow rate in L/min

• Water pressure

• Gas supply

• Product dimensions

• Controller compatibility

• External location

• Household demand

The best choice is the model that suits your home, not simply the brand with the most familiar name.

Bosch vs Rheem Instant Gas

Bosch and Rheem can both be compared for instant gas hot water.

Bosch may suit buyers focused on gas continuous flow systems.

Rheem may suit buyers comparing instant gas as part of a broader hot water system search.

Before choosing between Bosch and Rheem, check:

• Natural gas or LPG

• Flow rate

• Gas supply

• Water pressure

• Number of bathrooms

• External location

• Product dimensions

• Required valves and fittings

Both brands still need correct sizing and site suitability.

What Size Instant Gas Hot Water System Do You Need?

Instant gas systems are sized by flow rate in L/min.

Flow rate helps estimate how much hot water the system can supply at once.

A higher L/min model may suit larger households, but it is not automatically better. The property needs suitable gas supply and water pressure.

Best Instant Gas Brand for One Bathroom

A one-bathroom home may suit Rinnai, Bosch or Rheem depending on gas type, flow rate and usage.

For one bathroom, check:

• Number of occupants

• Shower habits

• Bath use

• Whether other hot taps run during showers

• Natural gas or LPG

• Gas supply

• Water pressure

• External wall location

• Product dimensions

A one-bathroom home with one or two people may not need the same flow rate as a one-bathroom family home.

Best Instant Gas Brand for Two Bathrooms

Two-bathroom homes need more careful instant gas sizing because showers and outlets may overlap.

A higher-flow instant gas system from Rinnai, Bosch or Rheem may suit if:

• The selected L/min rating matches demand

• Gas type is confirmed

• Gas supply can support the unit

• Water pressure and flow are suitable

• External location is practical

• Product clearances can be met

For two bathrooms, do not choose only by brand or product price. Flow rate, gas supply and water pressure matter more.

Best Instant Gas Brand for Families

Families usually have higher hot water demand, especially during morning and evening peaks.

Instant gas may suit a family if:

• The correct L/min model is selected

• Natural gas or LPG is available

• Gas supply is suitable

• Water pressure and flow are adequate

• The external wall location is suitable

• Household demand matches product specifications

For families, compare:

• Rinnai instant gas

• Bosch instant gas

• Rheem instant gas

Avoid choosing too low a flow rate just to reduce upfront product price.

Best Instant Gas Brand for Small Homes

Small homes may suit instant gas hot water if gas is available and the external location works.

A smaller or moderate-flow model may suit if:

• Hot water demand is low to moderate

• The home has one bathroom

• Gas supply is suitable

• Water pressure is suitable

• External wall space is available

• The household does not regularly run multiple hot outlets at once

Small homes still need proper checks. Do not assume the smallest model is automatically the best option.

Best Instant Gas Brand for Units

Units can be more complicated because of space, building rules, gas supply and location requirements.

Instant gas may suit a unit if:

• The building already supports gas hot water

• Natural gas or LPG is confirmed

• Body corporate rules allow the replacement

• External location is compliant

• Gas supply and water pressure are suitable

• Product dimensions suit the available space

• Delivery access is practical

Some units may be better suited to electric hot water systems if gas replacement is difficult.

Best Instant Gas Brand for Townhouses

Townhouses can suit instant gas hot water, but the layout needs careful checking.

Before choosing Rinnai, Bosch or Rheem for a townhouse, check:

• Side access

• External wall space

• Gas meter or LPG bottle location

• Distance from windows and openings

• Distance from bedrooms

• Neighbouring properties

• Body corporate or complex rules

• Gas pipe sizing

• Water pressure

• Product dimensions

Instant gas can be practical for townhouses where external location, gas supply and water pressure are suitable.

Best Instant Gas Brand for Rental Properties

Rental properties need practical hot water systems that suit likely tenant demand.

Instant gas may suit a rental if:

• Gas hot water is already installed

• The correct natural gas or LPG model is selected

• Gas supply is suitable

• Water pressure is suitable

• The external location works

• The selected L/min rating suits the number of occupants and bathrooms

For rentals, avoid undersizing. A lower product price may create more complaints if tenants experience poor hot water performance.

Best Instant Gas Brand for Renovations

Renovations are a good time to reassess instant gas hot water because the finished home may have higher demand than the old layout.

Instant gas may need a different model if:

• A second bathroom is being added

• More people will live in the home

• A bath is being added

• The old hot water location is changing

• Gas appliances are being added

• Gas pipework is being upgraded

• External wall space is being redesigned

• Water pressure issues are being addressed

Plan instant gas hot water around the finished property, not only the old system.

Gas Supply Requirements for Instant Gas

Instant gas hot water performance depends heavily on gas supply.

Before choosing a brand or model, check:

• Gas meter capacity

• Gas pipe sizing

• Distance from gas supply

• Other gas appliances

• Natural gas or LPG setup

• Regulator requirements where relevant

• Appliance load

• Licensed gas fitter advice

A larger instant gas unit may not perform properly if the gas supply is not suitable.

Water Pressure and Flow Requirements

Instant gas systems need suitable water pressure and flow.

Before choosing an instant gas brand, check:

• Mains water pressure

• Existing shower flow

• Number of hot outlets

• Whether outlets may run together

• Existing pipework

• Pressure limiting valves

• Product specifications

• Licensed plumber advice where needed

If the water supply is poor, replacing the hot water system alone may not solve the problem.

External Location and Clearances

Most instant gas systems are external units unless the specific product is designed and approved for internal or flued installation.

Before choosing an instant gas system, check:

• External wall location

• Clearance from windows and doors

• Clearance from openings

• Distance to gas supply

• Distance to water connections

• Access for servicing

• Weather exposure requirements

• Product installation requirements

Do not assume an external gas unit can be installed indoors. Product type and compliance requirements matter.

Controllers and Temperature Settings

Some instant gas systems may be compatible with temperature controllers, depending on the model.

Before ordering controllers or accessories, check:

• Product compatibility

• Whether controllers are included

• Number of controllers supported

• Controller location

• Wiring requirements

• Whether old controllers are compatible

• Licensed trade requirements

Do not assume existing controllers will work with every new instant gas unit.

Instant Gas vs Electric Storage

Instant gas and electric storage suit different homes.

Instant gas may suit if:

• Natural gas or LPG is available

• Continuous flow hot water is preferred

• Gas supply and water pressure are suitable

• External wall location is practical

• Tank space is limited

Electric hot water systems may suit if:

• Gas is not available

• A storage tank is already installed

• A simple like-for-like replacement is preferred

• Gas supply upgrades are not practical

• External gas placement is difficult

The right choice depends on the property and energy source.

Instant Gas vs Heat Pump Hot Water

Instant gas and heat pump hot water are very different system types.

Instant gas may suit if:

• Gas is available

• Continuous flow hot water is preferred

• Gas supply and water pressure are suitable

• External wall location is practical

Heat pump hot water systems may suit if:

• Efficient electric hot water is preferred

• Outdoor airflow is suitable

• Tank capacity suits the household

• Condensate drainage can be managed

• Noise placement is acceptable

• Electrical requirements can be met

Instant gas is measured by L/min. Heat pump systems are storage systems measured by tank capacity in litres.

Supply-Only Pricing vs Installed Cost

When comparing instant gas hot water brands online, make sure you understand what the price includes.

Hot Water Outlet sells supply-only hot water systems and accessories online. Supply-only pricing usually does not include:

• Installation

• Plumbing labour

• Gas fitting

• Electrical work

• Old unit removal

• Disposal

• Valves

• Fittings

• Pipework changes

• Gas upgrades

• Controller wiring

• Compliance upgrades

• Concrete bases or platforms

• Delivery beyond what is shown at checkout

Before ordering, confirm the full job requirements with appropriately licensed tradespeople.

Valves, Fittings and Accessories

An instant gas hot water order may need more than the main unit.

Common accessories include:

• Tempering valves

• Pressure relief valves

• Duo valves

• Non-return valves

• Isolation valves

• Copper pipework

• Gas fittings

• Controllers where compatible

• Drainage parts

• Connection parts

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.

Common Mistakes When Choosing an Instant Gas Brand

Choosing Brand Before Gas Type

Confirm natural gas or LPG before choosing the exact model. Gas type must be correct.

Choosing Flow Rate by Price Alone

A lower-flow model may not suit families, two bathrooms or overlapping showers.

Ignoring Gas Supply

Instant gas systems need suitable gas supply. A larger unit may need gas supply checks.

Ignoring Water Pressure

Poor water pressure can affect instant gas performance.

Comparing L/min With Storage Litres

Instant gas is sized by flow rate in L/min. Storage hot water is sized by tank capacity in litres.

Assuming External Units Can Go Indoors

External instant gas units are outdoor/external only unless the specific product is designed and approved for internal or flued installation.

Forgetting Controller Compatibility

Controllers may not be included or compatible with every model.

Comparing Supply-Only Price to Installed Cost

Supply-only product pricing is not the same as total replacement cost.

Forgetting Valves and Fittings

The hot water unit may not be the complete order.

Instant Gas Brand Buyer Checklist

Before choosing an instant gas hot water brand, check:

• Current hot water system brand and model

• Current system type

• Current flow rate in L/min

• Whether the current system keeps up

• Natural gas or LPG

• Number of people in the home

• Number of bathrooms

• Shower habits

• Bath use

• Required flow rate in L/min

• Gas supply suitability

• Water pressure and flow

• External location

• Product dimensions

• Connection positions

• Controller compatibility where relevant

• Delivery access

• Required valves and fittings

• Warranty information

• Licensed trade requirements

Compare Instant Gas Hot Water Brands Online

Hot Water Outlet makes it easier to compare instant gas hot water systems by brand, flow rate, gas type, dimensions, specifications and supply-only pricing.

Start with:

• Instant Gas Hot Water Systems

• Gas Hot Water Systems

• Hot Water Systems

Then compare brands:

• Rinnai Hot Water Systems

• Bosch Hot Water Systems

• Rheem Hot Water Systems

FAQs About Instant Gas Hot Water Brands

What is the best instant gas hot water brand?

Rinnai, Bosch and Rheem are commonly compared for instant gas hot water. The best brand depends on gas type, required L/min flow rate, gas supply, water pressure, bathroom count, location and product specifications.

Is Rinnai better than Bosch for instant gas hot water?

Rinnai and Bosch are both commonly compared for instant gas hot water. The better choice depends on the exact model, gas type, flow rate, controller needs, gas supply, water pressure and location.

Is Rheem good for instant gas hot water?

Rheem is commonly compared for instant gas hot water as well as broader hot water categories. It may suit buyers who want to compare instant gas against electric, gas storage and heat pump options.

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 models, while larger families or two-bathroom homes may need higher-flow systems, subject to gas supply and water pressure.

Is 26L instant gas hot water enough for two bathrooms?

A 26 L/min instant gas system may suit some two-bathroom homes, but gas supply, water pressure, shower habits and simultaneous outlet use must be checked before ordering.

Is instant gas better than gas storage?

Instant gas may suit homes wanting continuous flow hot water where gas supply and water pressure are suitable. Gas storage may suit homes replacing an existing tank-style gas system. Neither is automatically better.

Can instant gas hot water run out?

Instant gas systems do not run out in the same way as storage tanks because they heat water as it flows. However, performance still depends on flow rate, gas supply, water pressure and the number of outlets being used.

Can instant gas hot water be installed indoors?

External instant gas units are outdoor/external only unless the specific product is designed and approved for internal or flued installation. Always check product requirements and licensed trade advice.

Do instant gas systems need valves and fittings?

Some instant gas replacements require valves, fittings, controllers or accessories depending on system type 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 plumbing, gas fitting and sometimes electrical work that should 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 Brand for Your Home

The best instant gas hot water system brand depends on your gas type, household demand, required flow rate, gas supply, water pressure and available location. Rinnai, Bosch and Rheem are all worth comparing, but the right choice is the model that suits your home.

Browse instant gas hot water systems online with Hot Water Outlet to compare brands, flow rates, specifications and supply-only pricing.