Instant Gas Hot Water Systems Brisbane

Instantaneous gas hot water heaters provide on-demand hot water in a compact, space-saving unit. Without the need to store hot water, instant gas hot water systems are an energy-efficient alternative to storage tank. Continuous flow systems heat the water using a powerful fan-forced burner and copper heat exchanger. Their ability to produce high quantities of hot water while reducing overall energy consumption makes them a favourite amongst our customers.

Dux instantaneous gas hot water system Brisbane

The rapid evolution of continuous flow technology in Australia has led to increased energy efficiency and unit affordability.  The new generation of continuous flow water heaters are extremely versatile and reliable. Unlike the temperamental units of the past (such as the old Bosch Hydro) today’s units are highly sophisticated and reliable. Recent improvements include the ability to operate on a low flow rate and deliver a constant preset temperature.  No more cold showers and regular maintenance!

Another advantage of an instant gas hot water heater is the cost of compliance. Continuous-flow water heaters do not require concrete slabs, drain lines and pressure relief valves. These costs really add up for storage gas and electric hot water installations.

Not all plumbing systems are compatible with instant gas hot water. The installation of gas continuous-flow hot water systems is not recommended for properties with low gas pressure or water flow. Properties with galvanised pipework and water-saving shower head are also more susceptible to temperature fluctuation. For more information regarding your property’s compatibility, please contact a hot water specialist for advice.

Size and Type:

Gas continuous flow hot water system ranges from 12 to 27 litres per minute delivery. In order to select the right size unit its important to consider the following factors:

– Number of users.
– Cold, Hot and Gas pipe sizing.
– Available Gas Pressures.
– Availability of a power source.

Condensing Vs Non-Condensing:

Non-Condensing units are extremely popular and readily available across Australia. Models such as the Rheem Metro, Rinnai Infinity and Dux E series are perfectly suited to domestic applications. These units are affordable, easy to install and can reach up to 6-star efficiency.

With the introduction of condensing technology, instant gas hot water has never been better.   Condensing units are perfect for new homes or green consumers who are environmentally conscious. Condensing hot water systems range between 6.2 and 7 efficiency, however, the trade-off is a more expensive unit price and installation. Depending on the application, this cost may be recouped over time from a reduction in energy bills.

Controllers and Preset Temperatures

A number of continuous flow water heaters are compatible for use with a Kitchen and Bathroom remote controller. While some homeowners like this feature, due to the restricted delivery temperature in Australia, the controllers have limited functionality.

50 degree preset – Standard unit designed for domestic application.

60 degree preset – Designed for use with properties with both tempered and untempered hot water services.

75 degree preset – Commercial application to be used in conjunction with a storage tank.

Commercial Applications

Continuous flow water heaters are very effective in high demand commercial situations. This is due to their ability to heat large volumes of water in a short space of time make. Units such as the Rinnai HD200E can be used as a stand alone unit or as a booster for a storage heater. Combination systems, such as the Demand Duo, are a perfect match for unit complexes and high demand body corporate applications.

Gas Types (Brisbane/ Queensland/ Australia)

Instant gas hot water systems are available in Natural gas and LPG (propane) gas types.

For natural gas applications, a medium or high pressure gas service is required. For gas availability in your area, contact the natural gas hotline on 1300 001 001. In L.P.G. applications, we recommend using a minimum of two 45kg gas bottles. Due to the high demand of continuous flow water heaters, a dual stage regulator is also required.    


Instant gas hot water heaters installations must achieve adequate flue clearances from doors and windows. All installations must include a means of isolation for both cold water supply and gas supply services. In keeping with the plumbing code, insulation must be installed on the supply pipework. In Brisbane, a Form 4 must be submitted to council and a gas plate and certificate must be completed.  


In order to achieve the necessary water flow rate and gas delivery, the following works may be required;

– Upgrading of the gas service from 15mm to 20mm to achieve the correct Mj/H delivery.
– Upgrading the cold water and hot water supply lines from 15mm to 20mm.
– Installation of a waterproof power point in close proximity of the unit.
– Installation of a power flue for internal units.
– Condensate drain line for condensing units.

Please see details below outlining the available sizes and warranty information for the most popular gas continuous flow hot water systems we install:

Rinnai hot water service Brisbane

Model B16 B20 B26
Litres/min 16 20 26
Ignition Electronic
Gas Type Natural Gas and LPG
Efficiency 6+ Stars
Pre-set temperature 50ºC and 60ºC
Warranty Heat exchanger 10 years including 3 years parts & labour
Dux hot water








Litres/min 17 21 26
Ignition Electronic
Gas Type Natural Gas and LPG
Efficiency 6+ Stars
Pre-set temperature 50ºC or 60ºC
Warranty Heat exchanger 12 years including 3 years parts & labour



876E16, 874E16


875E24, 871E24


875E26, 871E26

Litres/min 16 24 26
Ignition Electronic
Gas Type Natural Gas and LPG
Efficiency 6 Stars
Pre-set temperature 50ºC and 60ºC
Warranty Heat exchanger 10 years including 3 years parts & labour

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