4 Best Gas Hot Water Systems

Gas hot water systems are efficient water heating appliances that use natural gas or LPG to heat water for residential and commercial use. These systems come in two main types: storage systems that maintain a tank of hot water and continuous flow systems that heat water on demand. Gas systems work by igniting gas in a burner which heats water either in a tank or through a heat exchanger. They offer benefits such as faster heating times compared to electric systems, lower running costs when using natural gas, and the ability to provide hot water during power outages.

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The best choice for your home will depend on your specific needs. Different gas hot water systems are better suited to various household dimensions, family size, hot water usage patterns, and purpose. Larger homes with higher hot water demands might require systems with greater capacity or flow rates, while smaller households can benefit from more compact, economical options.

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1. Rheem Gas Hot Water Heaters

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Rheem gas hot water heaters are trusted Australian systems available in both storage and continuous flow options. Popular models include the Rheem Stellar series for continuous flow and the Rheem 5 Star range for storage tanks.

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Rheem continuous flow units deliver impressive flow rates of 16-27 litres per minute, while their storage tanks offer recovery rates of approximately 200 litres per hour. This makes them suitable for medium to large households with multiple bathrooms requiring simultaneous hot water access.

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These systems are ideal for homes with existing natural gas connections or properties with access to LPG. Installation requires proper gas line connection with adequate pressure, appropriate fluing for exhaust gases, and cold water supply connection. The units must be installed outdoors or in well-ventilated areas with sufficient clearance from windows and other structures for safety reasons.

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2. Dux Gas Hot Water Heaters

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Dux gas hot water heaters are Australian-manufactured systems known for their reliability and efficiency. Key models include the Dux Prodigy storage tanks and the Condensex continuous flow range.

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Dux continuous flow systems provide flow rates of 13-26 litres per minute, while their storage systems offer recovery rates of approximately 170-220 litres per hour. These specifications make Dux heaters appropriate for small to large households depending on the chosen model.

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These systems work well in suburban homes with steady hot water usage patterns. Installation requires connection to gas supply lines with correct pipe sizing, water connections with appropriate pressure limiting devices, and proper ventilation for combustion air. The systems need to be mounted on non-combustible surfaces and positioned to allow easy access for maintenance and servicing.

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3. Rinnai Gas Hot Water Heaters

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Rinnai gas hot water heaters are known for their innovative technology and reliability. Their Infinity continuous flow series and HotFlo storage tanks are popular choices in the Australian market.

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Rinnai continuous flow systems deliver flow rates between 16-26 litres per minute, with advanced models featuring temperature controllers for precise water temperature. Their storage systems offer recovery rates of approximately 190 litres per hour. These specifications suit various household sizes from singles to large families.

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These systems are excellent for homes seeking energy-efficient hot water solutions. Installation requirements include appropriate gas line sizing, adequate water pressure, and suitable mounting locations. Continuous flow units require installation of a condensate drain for high-efficiency models, and all systems need proper clearance from combustible materials and building openings.

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4. Bosch Gas Hot Water Heaters

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Bosch gas hot water heaters feature German engineering excellence with high-efficiency ratings. Their 4000S and 5000S continuous flow ranges are particularly well-regarded for their performance.

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Bosch systems provide flow rates of 10-25 litres per minute depending on the model, with precise electronic temperature control allowing water heating to exactly the desired temperature. These systems are suitable for various household sizes from small apartments to large family homes.

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These gas hot water systems are perfect for environmentally-conscious households seeking to minimise energy use. Installation requirements include connection to appropriately sized gas lines, water connections with isolation valves, and mounting in locations protected from extreme weather. The systems need clearance around air intake and exhaust components, and must comply with local gas fitting regulations.

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What is a Gas Hot Water System?

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A gas hot water system is a water heating appliance that uses natural gas or LPG (Liquefied Petroleum Gas) as its primary energy source to heat water for residential and commercial use. These systems are available in two core variants: storage systems and continuous flow types. The main function of a gas hot water system is to heat cold water to a specified temperature using a gas burner, making hot water readily available for household activities.

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In domestic environments, gas hot water systems are commonly used for everyday tasks such as showering, bathing, washing dishes, doing laundry, and cleaning. They are particularly popular in Australian homes due to their generally lower operating costs compared to electric systems and their ability to heat water quickly. Gas systems are also valued for their reliability during power outages, as many models can continue to provide hot water even when electricity is unavailable.

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What are the Types of Gas Hot Water Systems?

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• Gas Storage System: This type features a tank that stores pre-heated water ready for use. Cold water enters the tank and is heated by a gas burner located at the bottom. The hot water is stored in an insulated tank until needed, with the system automatically reheating water when the temperature drops below a set level. Storage systems typically range from 90 to 360 litres in capacity and are suitable for households with moderate, consistent hot water needs.
• Instant or Continuous Flow: These tankless systems heat water on demand as it passes through a heat exchanger. When a hot water tap is opened, water flows through the unit where it is rapidly heated by gas burners, providing a continuous supply of hot water. There is no storage tank, which makes these systems compact and eliminates standby heat loss. They typically provide 10-27 litres of hot water per minute depending on the model size.
• Condensing Gas Systems: A more advanced variant of continuous flow systems, these capture heat from exhaust gases that would otherwise be lost, redirecting it to preheat incoming cold water. This design achieves higher energy efficiency rates of up to 95%, compared to 80-85% for standard gas systems. They require drainage for condensate but offer reduced energy consumption and operating costs.

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In terms of efficiency, continuous flow systems generally offer better energy performance as they only heat water when needed, eliminating standby heat losses associated with storage tanks. However, storage systems can deliver higher initial flow rates and may handle multiple simultaneous hot water demands better. For space considerations, continuous flow systems are significantly more compact and can be wall-mounted, making them ideal for homes with limited space. Storage systems require floor space for the tank but may better serve households with high simultaneous hot water demands.

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How Does a Gas Hot Water System Work?

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Gas hot water systems use the energy from burning gas to heat water for household use. The heating process differs between storage tank systems and continuous flow units, but both rely on the same fundamental principles of gas combustion and heat transfer. Here's how each type works:

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Storage Gas Hot Water System:

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Step 1: Cold water enters the tank through an inlet pipe at the bottom of the tank.

Step 2: The thermostat detects the water temperature is below the set level and signals the gas control valve to open.

Step 3: The gas burner ignites beneath the storage tank, creating a steady flame.

Step 4: Heat from the flame transfers through the tank's base and into the water.

Step 5: As water heats, it naturally rises to the top of the tank due to convection currents.

Step 6: When a hot water tap is turned on, hot water exits from the top of the tank.

Step 7: Cold water simultaneously flows into the bottom of the tank to maintain the water level.

Step 8: The thermostat continuously monitors water temperature and cycles the burner on and off to maintain the set temperature.

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Continuous Flow Gas Hot Water System:

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Step 1: A hot water tap is opened, creating water flow through the system.

Step 2: Water flow sensors detect the movement of water and activate the system.

Step 3: The electronic ignition system lights the gas burner.

Step 4: Cold water passes through a heat exchanger—a series of pipes above the gas burner.

Step 5: As water flows through the heat exchanger, it rapidly absorbs heat from the gas flame.

Step 6: Temperature sensors monitor the outgoing water temperature.

Step 7: The system modulates the gas supply and flame intensity to maintain the preset water temperature.

Step 8: Hot water at the desired temperature flows out of the tap for use.

Step 9: When the tap is closed, the flow sensor detects the cessation of water movement.

Step 10: The gas burner automatically shuts off until hot water is requested again.

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What are the Benefits of Using a Gas Hot Water System?

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Gas hot water systems offer several advantages that make them a popular choice for Australian homes. These benefits range from performance characteristics to practical considerations for households with varying hot water demands:

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• Quick heating time: Gas systems heat water significantly faster than electric alternatives. Storage units recover their tank temperature rapidly after use, while continuous flow systems provide hot water almost instantly.
• Cost-effective over electric in long-term: Although installation costs may be higher initially, gas hot water systems typically offer lower running costs compared to standard electric systems, especially in homes with high hot water usage. Natural gas is often less expensive than electricity for water heating purposes.
• Available during power outages: Many gas hot water systems can continue functioning during electrical power outages, as they require minimal or no electricity. This makes them reliable options for areas with unstable power supply.
• Suits large household use: Gas systems are well-suited for larger households with high hot water demands. Their faster recovery rates and higher flow capacities can accommodate multiple simultaneous users without running cold.
• Generally higher flow rates: Gas continuous flow systems typically deliver superior water flow rates compared to electric instantaneous systems, providing more consistent performance when multiple taps are used simultaneously.
• Can be installed externally: Most gas hot water systems are designed for external installation, which saves valuable indoor space and eliminates concerns about ventilation requirements inside the home.

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What are the Disadvantages of Using a Gas Hot Water System?

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Despite their many benefits, gas hot water systems do have some drawbacks that should be considered when making your selection:

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• Requires gas connection or LPG availability: These systems require access to natural gas connections or regular LPG bottle deliveries, which may not be available or convenient in all locations.
• Higher upfront installation cost: The initial purchase and installation costs for gas hot water systems are typically higher than those for standard electric systems, particularly if gas connections need to be established.
• Potential CO2 emissions: Gas systems produce carbon dioxide emissions during operation, making them less environmentally friendly than heat pump or solar hot water alternatives.
• Periodic servicing of gas components: Gas systems require regular maintenance of specialised components such as gas valves, burners, and flues to ensure safe and efficient operation, which can add to ongoing costs.
• Outdoor placement may need weatherproofing: External installation, while space-saving, may expose units to harsh weather conditions, potentially requiring additional weatherproofing measures or affecting longevity.
• Efficiency may vary if improperly sized: Selecting a gas system that is too large or too small for household requirements can lead to inefficient operation, increased running costs, and reduced performance.

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What is the Efficiency of Gas Hot Water Systems Compared to Electric?

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The efficiency of hot water systems is measured by how effectively they convert energy into heat for water. Gas hot water systems compared to electric typically achieve efficiency ratings of 80-95%, meaning they convert 80-95% of the gas energy into heat for water. Standard electric resistance hot water systems have nearly 100% efficiency in converting electricity to heat, but this doesn't account for the efficiency losses in electricity generation and transmission.

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When considering overall energy efficiency from source to delivery, gas systems often perform better than standard electric systems due to the energy losses associated with generating and transmitting electricity. However, heat pump electric systems can achieve efficiency ratings of 300-400% as they extract heat from the surrounding air rather than generating it directly.

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The Seasonal Energy Efficiency Ratio (SEER) varies for gas systems depending on climate conditions, usage patterns, and system type. In colder climates, gas systems maintain more consistent performance compared to air-source heat pumps, which can lose efficiency in low temperatures. Continuous flow gas systems typically offer better SEER values than storage systems as they eliminate standby heat losses, with modern condensing models achieving the highest efficiency ratings in the gas category.

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What are the Features of the Best Electric Hot Water System?

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The best electric hot water systems combine performance, durability, and efficiency to provide reliable hot water while keeping running costs reasonable. These key features differentiate premium systems from basic models:

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• High energy efficiency: Top electric hot water systems feature high energy efficiency ratings, typically displayed as energy star ratings (4 stars and above) or efficiency percentages (90%+). These systems use superior insulation materials to reduce heat loss and incorporate smart heating technology that minimises electricity consumption while maintaining consistent water temperature.
• Strong tank material: Premium electric hot water systems are constructed with corrosion-resistant, durable tank materials. Stainless steel tanks offer excellent longevity and corrosion resistance, particularly in areas with hard or aggressive water. Other high-quality options include tanks with marine-grade enamel coating or sacrificial anodes that protect against rust and extend the system's operational life.
• Dual/multi-element heating: Leading electric hot water systems often feature dual or multiple heating elements that provide faster recovery times and more flexible heating options. These systems can heat water in different sections of the tank simultaneously or sequentially, improving efficiency and ensuring hot water availability even during periods of high demand.
• Digital temperature control: Advanced temperature control interfaces allow precise temperature settings and monitoring. These digital systems enable users to program heating schedules, adjust temperatures with greater accuracy, and often include smart features that learn household usage patterns to optimise heating cycles and energy consumption.
• Good manufacturer warranty: The best electric hot water systems come with comprehensive warranties of 10 years or more on the tank and typically 2-5 years on electrical components. These extended warranties reflect the manufacturer's confidence in their product quality and provide homeowners with valuable protection against premature system failure.
• Consistent heat recovery rate: Superior electric systems maintain fast and consistent heat recovery rates, measured by how quickly they can reheat a depleted tank. The best systems can heat water at rates of 120-200 litres per hour, ensuring minimal wait times between heavy usage periods and reliable hot water supply for back-to-back showers or simultaneous use in multiple bathrooms.

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What to Consider When Choosing a Gas Hot Water System?

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Choosing the right gas hot water system requires careful consideration of several key factors that affect performance, cost, and suitability for your specific household needs. Your household size and hot water usage patterns are primary considerations, as they determine the capacity or flow rate required to meet your demands. The available space for installation will influence whether a compact continuous flow system or larger storage tank is appropriate. Your existing gas supply type (natural gas or LPG) and connection availability will limit your options, while installation requirements including ventilation, fluing, and clearances must comply with Australian standards. Budget considerations should covers both initial purchase costs and long-term running expenses, with energy efficiency ratings helping to predict ongoing operational costs. Climate conditions in your location can affect system performance, particularly for external installations and heat pump supplementary systems. Future household growth plans should be factored in to avoid premature system replacement. Water quality in your area may necessitate additional water treatment systems to protect against scale build-up and corrosion. Lastly, warranty periods offered by manufacturers provide valuable insight into the expected durability and quality of different systems, with premium models typically offering more comprehensive coverage.

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Best Gas Hot Water System for Large Households

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Large households, typically defined as homes with 4 or more residents or 3+ bathrooms with potential simultaneous hot water usage, require high-capacity systems capable of meeting substantial demand. For these households, we recommend continuous flow systems with flow rates of 26 litres per minute or greater, or storage tanks of at least 170 litres.

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The Rinnai Infinity 26 and Infinity 32 continuous flow models are excellent choices, offering outstanding flow rates of 26-32 litres per minute respectively, with the ability to supply multiple bathrooms simultaneously without loss of pressure or temperature. These systems can be linked in tandem for extremely high-demand situations and feature precise digital temperature control.

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For those preferring storage tanks, the Rheem Stellar 360-litre system provides exceptional capacity with a fast recovery rate of approximately 200 litres per hour, making it suitable for large families with staggered but frequent hot water usage. The Dux Prodigy 5 Star 170L is another worthy option, offering high energy efficiency with its 5-star rating while still providing ample hot water for larger households.

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The Bosch 8000S series continuous flow units, with flow rates up to 28 litres per minute, represent the premium end of the market with their high-efficiency condensing technology and precise electronic temperature control. These systems are ideal for large, modern homes with multiple simultaneous hot water demands across several bathrooms, laundry, and kitchen.

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Best Gas Hot Water System for Small Households

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Small households, typically consisting of 1-2 residents living in apartments, units, or small houses with 1-2 bathrooms, require more compact and economical hot water solutions. These households have lower simultaneous hot water demands and can benefit from appropriately sized systems.

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The Rinnai B16 continuous flow system is an ideal option for small households, offering a moderate flow rate of 16 litres per minute, which is perfectly adequate for single bathroom homes. Its compact design allows for flexible installation in limited spaces, and its lower gas consumption matches the reduced hot water needs of smaller households.

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Bosch's 4000S series provides excellent reliability in a compact package, with models delivering 13-16 litres per minute. These units are particularly suited to apartments and townhouses where space is at a premium but performance cannot be compromised.

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For those preferring storage systems, the Dux ProdigyLT 90L storage tank offers a good balance of capacity and economy for smaller households. Its compact dimensions make it suitable for installation in tight spaces while still providing enough hot water for typical small household needs.

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The Rheem Metro 90L is another excellent storage tank option, specifically designed for small households with its modest capacity and quick recovery rate. Its smaller footprint makes it ideal for units and townhouses where outdoor space is limited.

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Best Electric Hot Water System for Commercial Buildings

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Commercial buildings have distinct hot water requirements characterised by multiple fixtures being used simultaneously, extended operating hours, and potentially high-volume usage periods. These environments need robust systems capable of handling intensive demands reliably.

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The Rheem Heavy Duty Electric range is specifically engineered for commercial applications, featuring 3-phase power capability for faster heating and recovery. Available in capacities from 250 to 400 litres, these units incorporate reinforced elements and multiple thermostats to handle the demanding requirements of commercial settings.

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Dux's Commercial Electric series offers exceptional durability with its marine-grade enamel coating and high-pressure tolerance. These systems come in various capacities up to 400 litres and include models with three-phase power options that provide rapid recovery for businesses with high hot water demands.

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The AquaMAX Industrial Electric range stands out with its stainless steel construction and modular design allowing for installation of multiple units in tandem. Available with three-phase power connectivity, these systems feature programmable temperature control and anti-legionella cycles particularly suitable for healthcare facilities and accommodation providers.

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Bosch Tronic 8000 commercial units offer European engineering quality combined with Australian compliance standards. These systems feature digital monitoring interfaces, customisable heating cycles, and three-phase power options making them appropriate for office buildings, restaurants, and small hotels requiring reliable hot water delivery.

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Best Electric Hot Water System for Energy Savings

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Energy-efficient electric hot water systems are those that achieve at least 90% efficiency in converting electricity into heated water, with minimal standby losses and smart control features that optimise operation.

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The Rheem Premier Hiline heat pump system leads the category with its exceptional energy efficiency, using up to 65% less electricity than conventional electric systems. It extracts heat from the surrounding air rather than generating it directly, making it particularly effective in warmer climates and providing significant long-term energy savings.

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For maximum energy efficiency, solar-electric hybrid systems like the Solahart PowerStore offer the best solution. These systems use rooftop solar collectors to heat water naturally, with an electric booster element that activates only when solar input is insufficient. This combination can reduce hot water energy costs by up to 80% compared to standard electric systems.

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The AquaMAX Eco-Runner series incorporates advanced insulation technology and programmable operation to minimise energy consumption. Its smart timer functions allow the system to heat water only during off-peak electricity periods, further reducing running costs while maintaining hot water availability.

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The Dux Airoheat heat pump range combines excellent energy efficiency with reliability, using minimal electricity to transfer heat rather than generate it. These systems operate effectively even in temperatures as low as -5°C, making them suitable for energy-conscious households across most Australian climate zones.

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How do Gas Hot Water Systems Compare with Electric Systems?

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When choosing between gas and electric hot water systems, several key factors should be considered to determine which option best suits your specific needs. The following comparison examines the key differences between these two heating technologies:

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Each system type offers distinct advantages depending on your household requirements, existing infrastructure, climate conditions, and budget considerations. Gas systems generally excel in high-demand situations where flow rate is important, while certain electric options like heat pumps and solar-electric hybrids offer superior energy efficiency for environmentally conscious consumers.

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