Instant Gas Hot Water Systems from $929
Our Top 3 Instant Gas Systems
Choose How You Want to Order
Not every hot water job is the same. Choose supply only if you already have an installer arranged, select supply and installation together where available, or compare your options if you are still deciding what best suits your home.
Supply Only
Best if you already have a licensed plumber, gas fitter or electrician arranged.
You receive the hot water system and the components listed with that product. Installation and site-specific work are not included unless shown or selected separately.
Valves, old unit removal, disposal, electrical work, pipework changes, gas work, drainage or compliance upgrades may be required depending on your installation.
Supplied & Installed
Best if you want the hot water system and installation organised together.
Select your preferred system, complete the installation questions on the product page and choose any applicable installation options before checkout.
Installation availability and final requirements depend on your location, access, existing services, selected system and site conditions.
Not Sure What You Need?
The right hot water system depends on household demand, energy source and your existing installation.
Compare electric, gas, heat pump and solar hot water systems using the ranges and selection tools throughout the site.
Consider household size, available space, energy source, recovery requirements, running costs and installation requirements before choosing.
Instant Gas Hot Water Systems: Prices, Replacement Costs & Buying Guide
Instant gas hot water systems, also known as continuous-flow gas hot water systems, heat water as it passes through the appliance instead of storing a full tank of hot water. They provide a compact hot water option for homes with a suitable natural gas or LPG supply.
Installed Today offers instant gas hot water systems for supply across supported mainland Australian metro areas, with supplied and installed options available on selected systems in eligible Brisbane and Gold Coast locations. Compare gas type, flow rate, simultaneous hot water demand, gas supply, water pressure, dimensions and installation requirements before choosing a system.
The current collection is advertised from $849. The product grid above is the live source for current product pricing, stock and variants; this guide explains how that product price relates to supply-only, like-for-like replacement and installed costs.
How Much Do Instant Gas Hot Water Systems Cost?
Instant gas pricing starts with the appliance itself, then changes with the installation pathway. A straightforward replacement can be very different from increasing flow rate, changing from gas storage to continuous flow, relocating the unit or upgrading the gas supply. At this September 2026 review, the collection is advertised from $849.
Product cards above override this guide if pricing changes. Delivery is not automatically included unless the selected product or checkout says so.
What Does the Instant Gas Hot Water Price Include?
The advertised product or “from” price is the starting appliance price. It is not automatically the complete installed price and should not be read as including every gas alteration, valve, wall-mounting change, power point, removal, disposal, delivery or site-specific requirement unless those items are explicitly shown in the selected option.
Supply Only
Choose supply only when you already have an appropriately licensed gas fitter or plumber arranged. The price covers the selected appliance and product options unless the listing says otherwise.
Like-for-Like Replacement
Replacing the same gas type and a similar flow-class unit in the same position can be the simplest installed pathway where gas supply, water connections, mounting, clearances and power remain suitable.
Extra Site Work
Gas pipe upgrades, higher flow demand, storage-to-instant conversion, relocation, electrical supply, mounting, valves, drainage and compliance changes can increase the completed cost.
How Much Does It Cost to Replace an Instant Gas Hot Water System?
There is no single replacement price that fits every property. Start with the live product price above, then compare the installation pathway that matches the existing system. A same-fuel, similar-flow, same-position replacement usually has fewer variables than increasing flow rate, changing appliance style or moving the unit.
Same Gas Type & Similar Flow
Often the lowest-complexity pathway where natural gas or LPG, gas pipe capacity, connection positions, wall mounting, clearances and power supply already suit the replacement.
16L, 20L or 26L Upgrade
Moving to a higher flow class can change gas demand and may require larger pipework, different connection positions or other installation changes even when the old unit was also continuous flow.
Gas Storage to Instant Gas
This is a conversion rather than a simple replacement and can add wall mounting, gas pipework, water connection changes, electrical power, removal and disposal of the old storage tank.
Do not judge the cheapest replacement by the appliance price alone. A model that closely matches the existing installation can sometimes be a lower-complexity completed job than a cheaper unit requiring gas or service upgrades.
What Matters When Comparing Instant Gas Hot Water?
What Is an Instant Gas Hot Water System?
When a hot tap is opened, cold water flows through the continuous-flow unit. The burner activates and heats the water as it passes through the heat exchanger before supplying the hot water outlet.
Because the unit does not maintain a large stored tank of heated water, instant gas systems are generally compact and are commonly mounted on an external wall.
Continuous-flow systems are normally selected by flow rate rather than tank capacity. The required flow depends on the household, number of bathrooms, simultaneous outlets, desired water temperature and conditions at the property.
Natural Gas vs LPG Instant Hot Water
Natural Gas
Natural gas continuous-flow systems are designed for properties connected to an appropriate mains natural gas supply.
If an existing continuous-flow unit already uses natural gas, another suitable natural gas model is generally the first replacement option to compare.
LPG
LPG continuous-flow systems are designed for properties using bottled or bulk LPG rather than mains natural gas.
They can suit homes, acreage properties, granny flats and other applications where LPG is already available.
Do Not Guess the Gas Type
Natural gas and LPG appliances are different configurations. Confirm the fuel type before ordering the replacement system.
If you are unsure, have the existing installation checked by an appropriately licensed gas fitter.
What Size Instant Gas Hot Water System Do You Need?
Instant gas systems are commonly grouped by litres-per-minute flow class. The number is useful for comparison, but the actual amount of hot water available varies with temperature rise, water pressure, gas supply and operating conditions.
| Flow Class | Common Starting Point | Typical Application | Important Checks |
|---|---|---|---|
| 16L | Lower hot water demand | Smaller homes, units, granny flats and households with limited simultaneous hot water use | Bathrooms, shower demand, inlet temperature and gas supply |
| 20L | Small to medium households | Homes wanting more flow while retaining a compact continuous-flow system | Simultaneous outlets, water pressure and available gas capacity |
| 26L | Family homes and stronger demand | Homes where more than one hot water outlet may be required close together | Gas pipe sizing, temperature rise and realistic peak demand |
| Higher Flow | Higher-demand applications | Properties requiring additional continuous-flow capacity where the services can support it | Manufacturer specifications and licensed gas assessment |
Flow-rate classes are a starting point only. Individual system output depends on operating conditions and manufacturer specifications.
Instant Gas Hot Water Installation Price Drivers
The appliance price is only one part of the completed replacement. These are the main site factors that can change the installed cost of a continuous-flow gas hot water system.
| Price Driver | Why It Matters | Common Scenario |
|---|---|---|
| Natural gas or LPG | The appliance must match the property's actual fuel type | Replacing an LPG unit with the correct LPG version |
| Flow rate | Higher-flow appliances can require greater gas input | Changing from 16L or 20L to a 26L unit |
| Gas pipe capacity | Existing pipework may not deliver the required gas volume and pressure | Older or undersized gas line feeding a higher-input replacement |
| Connection positions | Gas, hot and cold connection locations vary between brands and models | Changing brand even when retaining the same flow class |
| Electrical supply | Many units require power for ignition, fans or electronic controls | Adding or relocating a suitable nearby power point |
| Wall mounting & clearances | The new appliance must suit the wall and required distances from openings and boundaries | Relocation because the old mounting point no longer suits |
| Storage-to-instant conversion | Changing system type adds removal, mounting and service alterations | Replacing a floor-mounted gas storage tank with wall-mounted continuous flow |
Bathrooms and Simultaneous Hot Water Use
Instant gas sizing should focus on how much hot water may be required at the same time, not simply the total number of people living in the home.
One Outlet at a Time
A smaller flow class may be suitable where hot water use is generally limited to one shower or outlet at a time.
Multiple Bathrooms
Homes where two showers or other hot water outlets may operate together generally need stronger continuous-flow capacity.
Usage Matters
Household size alone can be misleading. A larger household that rarely uses multiple outlets simultaneously may have different requirements from a smaller home with high concurrent demand.
Why Instant Gas Flow Rate Changes with Water Temperature
The advertised flow class does not mean the appliance will always deliver that exact volume of water at every hot water temperature.
Continuous-flow output is affected by the difference between the incoming cold water temperature and the required hot water temperature. When a greater temperature rise is needed, the available flow can be lower.
This is why climate, incoming water temperature and the number of outlets operating together should be considered alongside the advertised flow rating.
Gas Pipe Sizing Matters for Continuous Flow
Instant gas systems can have substantial gas input requirements. Existing gas pipework that operated an older or smaller appliance may not automatically be suitable for a larger replacement.
This becomes particularly important when upgrading flow rate or changing from gas storage to continuous flow.
Gas pipe size, length, available pressure, regulators and the total gas load from other appliances at the property need to be considered by an appropriately licensed gas fitter. Additional gas pipework may be required.
Does Instant Gas Hot Water Need Electricity?
Many modern continuous-flow gas hot water systems use electricity for ignition, controls and electronic operation even though gas provides the heat.
When replacing an existing unit, check whether the required electrical supply is already available in the correct location and whether it meets the selected appliance requirements.
Electrical work, relocation of a power point or changes to the electrical installation may be required in some replacement or conversion jobs.
Where Can an Instant Gas Hot Water System Be Installed?
Many residential continuous-flow gas systems are designed for external wall mounting. The installation location must comply with the manufacturer's instructions and applicable gas installation requirements.
Clearances around windows, doors, openings, corners, boundaries and other building features can affect where the appliance can be positioned.
The location should also allow suitable access to gas, cold water, hot water and electricity where required, while remaining practical for future servicing.
Instant Gas Controllers and Temperature Settings
Selected continuous-flow systems can operate with compatible temperature controllers or other control options, depending on the model.
Controllers can provide convenient temperature adjustment and system control, but compatibility varies between brands and models.
Check the individual product specifications if controllers or a particular temperature-control feature are important to the installation.
What Does an Instant Gas Hot Water System Cost to Own?
A lower purchase price does not automatically mean the lowest total cost. Compare the appliance price with installation complexity, fuel type and tariff, household demand, efficiency, servicing, warranty and whether the existing gas infrastructure can be reused.
Product
Appliance price, gas type, flow class, brand, controls and warranty.
Installation
Gas pipework, plumbing, wall mounting, electrical supply, access and compliance work.
Fuel
Natural gas or LPG cost, household demand, temperature rise and operating pattern.
Ownership
Warranty, servicing, parts support, controllers and future replacement compatibility.
Instant Gas Hot Water Systems Brisbane
Brisbane is a primary continuous-flow gas installation market for Installed Today. Selected instant gas hot water systems can be ordered with professional installation in eligible Brisbane, Logan, Ipswich, Moreton Bay and Redlands service areas, subject to the selected product, postcode, fuel type and installation requirements.
Common Brisbane jobs include replacing failed Rinnai, Rheem and Bosch continuous-flow units, changing flow rate to better suit household demand and converting suitable gas-storage installations to compact wall-mounted continuous flow.
Installation requirements may include gas pipe upgrades, plumbing, wall mounting, electrical work, valves, disposal and other compliance work depending on the existing installation.
Instant Gas Hot Water Systems Gold Coast
Installed Today also offers selected instant gas hot water systems supplied and installed across eligible Gold Coast service areas.
Continuous-flow gas can be a practical replacement where the home already has a suitable natural gas or LPG supply and the customer wants to retain a compact wall-mounted gas system.
The selected unit needs to suit household flow demand, fuel type, available gas supply, water pressure, installation clearances and electrical requirements.
Buy Instant Gas Hot Water Systems Across Major Australian Metro Areas
Customers who already have an appropriately licensed installer arranged can order instant gas hot water systems for supply across supported mainland Australian metro areas.
Our main continuous-flow gas markets include Brisbane, Gold Coast, Sunshine Coast, Sydney, Melbourne, Perth and Adelaide, together with major regional and metropolitan centres including Townsville, Cairns, Toowoomba, Newcastle, Central Coast, Wollongong and Geelong.
Installation availability is separate from product supply. Brisbane and Gold Coast are the primary installed markets, while customers in other supported areas can purchase supply only where delivery is available and arrange their own appropriately licensed gas fitter or plumber.
Replacing an Existing Instant Gas Hot Water System
If the existing continuous-flow system has provided enough hot water, replacing it with the same gas type and a similar flow class is generally the simplest starting point.
Before ordering, compare the existing appliance with the replacement.
- Natural gas or LPG
- Existing flow-rate class
- Number of bathrooms
- Simultaneous hot water demand
- Available gas supply
- Existing gas pipe sizing
- Water pressure and pipework
- Appliance dimensions
- Connection positions
- Wall-mounting position
- Installation clearances
- Electrical supply
Changing brand or flow rate does not always create a true like-for-like replacement. Connection positions, dimensions, mounting, gas demand and electrical requirements can differ between models.
Changing from Gas Storage to Instant Gas
Changing from gas storage to continuous flow can remove the large storage cylinder and replace it with a compact wall-mounted appliance. It can be a useful option where the property already has gas and the proposed installation suits continuous flow.
However, it is not simply a matter of removing one unit and attaching another. Continuous-flow systems can have substantially different gas input, water connection, wall-mounting and electrical requirements.
The gas supply should be assessed before assuming an existing gas-storage installation can support the selected continuous-flow appliance.
Instant Gas Hot Water Brands
The current Installed Today instant gas collection includes continuous-flow systems from Rinnai, Rheem and Bosch, with natural gas and LPG models available across different residential flow classes.
When comparing brands, look beyond the logo. Compare gas type, flow rate, dimensions, connection positions, warranty, controls, installation requirements and suitability for the existing gas supply.
For replacement work, a system that closely matches the property's services and household demand can be more practical than choosing solely by advertised flow rate or purchase price.
Instant Gas vs Gas Storage, Electric and Heat Pump Hot Water
Instant Gas
Compact wall-mounted hot water that heats water as required. Best considered where a suitable natural gas or LPG supply is already available.
Gas Storage
Stores hot water in a tank and can provide a straightforward replacement where an existing gas-storage setup already works well.
Electric or Heat Pump
Electric storage provides a straightforward non-gas option, while heat pumps are commonly considered where lower hot water electricity consumption is a priority.
Choose How You Want to Order
Supply Only
Choose supply only if you already have an appropriately licensed gas fitter or plumber arranged and simply need the continuous-flow unit supplied.
Installation, gas work, electrical work, valves, pipework, mounting, disposal and compliance upgrades are not included unless specifically shown.
Brisbane Installation
Selected instant gas hot water systems are available with installation in eligible Brisbane metro service areas.
Availability depends on product, postcode, gas type, existing services and installation conditions.
Gold Coast Installation
Supplied and installed continuous-flow gas options are also available for selected products in eligible Gold Coast areas.
Product and installation options are confirmed during the ordering process.
Instant Gas Hot Water Price, Replacement & Installation FAQs
How much does an instant gas hot water system cost?
The current Installed Today instant gas collection is advertised from $849 at this September 2026 review. The live product cards above remain the current price source. Final cost depends on the appliance, supply-only or installed pathway and any site-specific work.
Is the displayed instant gas price supply only?
The displayed product or “from” price is the starting appliance price unless the selected product or option specifically states installation is included. Review the installation choices before checkout.
How much does it cost to replace a 26L instant gas hot water system?
Start with the current 26L product price above, then add the relevant installation pathway. A like-for-like replacement can be simpler where gas type, gas pipe capacity, water connections, mounting, clearances and power supply already suit the new appliance.
How much does it cost to replace a 20L instant gas system?
The completed cost depends on the 20L appliance selected and how closely it matches the old unit. Changing brand can still alter connection positions, dimensions, mounting or gas demand, so compare the complete installation rather than flow rate alone.
What is the cheapest instant gas hot water replacement?
The lowest-priced appliance is not automatically the lowest completed replacement. A compatible like-for-like system can require less additional work than a cheaper unit needing gas pipe, mounting, electrical or relocation changes.
Is a 26L instant gas system better than a 20L system?
A 26L class provides greater potential flow, but it is not automatically the better fit. Household simultaneous demand, gas pipe capacity, water pressure, temperature rise and installation requirements should determine whether the extra flow is useful.
Can I replace a 16L instant gas unit with a 26L model?
It may be possible, but the higher-flow unit can have different gas input and service requirements. Gas pipe sizing, regulator capacity, water pressure, connections, mounting and electrical supply should be checked before treating it as a simple upgrade.
Can I replace gas storage with instant gas hot water?
Often yes where the property and gas supply suit the selected continuous-flow appliance. It is not automatically a direct swap; gas pipe sizing, wall mounting, water connections, clearances, electrical supply, removal and disposal may need to change.
What is the difference between natural gas and LPG instant hot water?
They are different fuel setups and the appliance must be suitable for the property's gas type. Do not assume natural-gas and LPG models are interchangeable; confirm the correct version before ordering.
Can I buy an instant gas hot water system supply only?
Yes. Supply only suits customers who already have an appropriately licensed gas fitter or plumber arranged or are outside an Installed Today installation area. Delivery availability depends on the product and destination.
Can Installed Today organise instant gas installation?
Selected instant gas systems are available with installation in eligible Brisbane and Gold Coast service areas. Availability depends on product, postcode, gas type, existing services and site conditions.
Is delivery included in the advertised price?
Do not assume delivery is included unless the selected product, promotion or checkout specifically says so. Product supply and installation are separate considerations.
Compare More Than the Flow-Rate Number
A suitable instant gas hot water system needs to match the fuel supply, peak household demand and installation conditions — not simply have the largest advertised litres-per-minute figure.
Compare natural gas or LPG, simultaneous hot water use, flow class, gas supply, water pressure, dimensions, controls, warranty, serviceability and installation requirements before ordering.
Product specifications, pricing and availability can change. Check the individual product information and selected installation option before placing your order.
Choose the Product First, Then Select Your Purchase Path
Use the product range above to compare current instant gas prices, natural gas and LPG variants, 16L, 20L and 26L flow classes, brands and available options. Choose supply only if your installer is already arranged, or select an installation option where available in Brisbane and Gold Coast.
Compare Instant Gas Hot Water Systems Above ↑Instant Gas Hot Water System FAQs
Common questions about choosing, ordering and installing continuous flow gas hot water systems for natural gas and LPG homes.
What is an instant gas hot water system?
An instant gas hot water system, also known as a continuous flow gas system, heats water as it passes through the unit. It does not store hot water in a tank, which makes it a compact option for many homes using natural gas or LPG.
Can I buy an instant gas hot water system supply only?
Yes. Choose supply only if you already have a licensed plumber or gas fitter arranged. Supply-only pricing is for the unit only and does not include installation, valves, old unit removal, disposal, gas work, pipework changes or compliance upgrades unless selected separately.
Can I order an instant gas hot water system supplied and installed?
Yes. Supplied and installed options are available for selected instant gas hot water systems in eligible Brisbane and Gold Coast service areas. Availability depends on your location, access, gas type, existing setup, product type and site requirements.
What is the difference between natural gas and LPG instant hot water?
Natural gas and LPG systems are not interchangeable unless the unit is specifically designed or correctly converted for that gas type. Always choose the correct model for your property and have gas work completed by a licensed gas fitter.
What size instant gas hot water system do I need?
The right size depends on household size, number of bathrooms, shower use, flow rate requirements, gas supply and incoming water temperature. Larger homes or homes with multiple bathrooms may need a higher flow rate model.
What does flow rate mean for instant gas hot water?
Flow rate is the amount of hot water the system can deliver per minute. A higher flow rate may better suit homes with multiple outlets, but performance still depends on gas supply, water pressure, temperature rise and the selected outlet temperature.
Are external instant gas hot water units suitable indoors?
External instant gas hot water units are designed for outdoor installation only. They should not be installed indoors unless the manufacturer specifically states the model is suitable for internal or flued installation.
Can an instant gas system replace a gas storage hot water system?
In some cases, yes. The replacement depends on your existing setup, gas supply, pipework, location, household demand, ventilation, clearances and current compliance requirements. Extra work may be required when changing from storage to continuous flow.
Does installation include gas pipework changes?
Gas pipework changes are not automatically included unless shown in the selected installation option or chosen as an add-on. Some properties may require pipe sizing checks, regulator work, valve upgrades or other compliance upgrades.
Does installation include old system removal and disposal?
Old system removal and disposal are not automatically included unless shown in the selected installation option or chosen as an add-on. Access, unit location, system type and site conditions can affect what is required.
Do instant gas hot water systems need power?
Many instant gas hot water systems need an electrical connection for ignition and controls. Requirements vary by model, so check the product specifications and installation requirements before ordering.
Do you install instant gas hot water systems in Brisbane and the Gold Coast?
Supplied and installed options are available in eligible Brisbane and Gold Coast service areas. Availability depends on the selected product, your address, gas type, access, existing system and installation requirements.