Rinnai B Series Instant Gas Hot Water Review: Is It Worth It?
The Rinnai B Series instant gas hot water range is a practical choice for households wanting continuous flow gas hot water without storing a full tank of heated water. Models such as the Rinnai B20 and Rinnai B26 are commonly compared by homeowners replacing older gas continuous flow units, upgrading from gas storage, or choosing between natural gas and LPG instant hot water systems.
For customers comparing products online, the Rinnai Infinity B26 Natural Gas Hot Water System, Rinnai Infinity B26 LPG Gas Hot Water System, Rinnai Infinity B20 Natural Gas Hot Water System and Rinnai Infinity B20 LPG Gas Hot Water System sit within Installed Today’s Instant Gas Hot Water Systems range.
The main appeal is simple: continuous flow gas hot water, compact wall-mounted design, strong brand recognition and no stored tank of hot water sitting outside. The main thing to get right is choosing the correct size, gas type and installation setup.
Quick Answer
Best for: homes already using natural gas or LPG instant hot water
Common sizes: 20L and 26L continuous flow models
Best Rinnai B20 fit: smaller to medium households with moderate hot water demand
Best Rinnai B26 fit: larger households, higher-use homes or properties with more bathrooms
Main advantage: continuous flow hot water without a storage tank
Main limitation: must be matched to the correct gas type, gas supply and flow demand
Good categories to compare: Gas Hot Water Systems, Instant Gas Hot Water Systems, 26L Instant Gas Hot Water Systems and Rinnai Hot Water Systems
What Is the Rinnai B Series?
The Rinnai B Series refers to Rinnai’s continuous flow gas hot water systems, commonly seen in models such as the B20 and B26. These systems heat water as it passes through the unit, rather than storing hot water in a tank.
When someone turns on a hot tap or shower, cold water flows through the unit, the burner activates, and the water is heated on demand. This is why these systems are often called instant gas hot water systems or continuous flow gas hot water systems.
They are popular for homes that want:
a compact wall-mounted unit
continuous hot water while gas and water supply are suitable
no large storage tank
natural gas or LPG options
a recognised hot water brand
a practical replacement for older instant gas units
If you are comparing Rinnai against other gas options, Installed Today’s Rinnai Hot Water Systems collection is the best starting point.
Rinnai B20 vs Rinnai B26
The biggest difference between the Rinnai B20 and Rinnai B26 is flow capacity.
A 20L continuous flow system is generally suited to smaller or medium homes with moderate hot water demand. It may suit townhouses, units, smaller families, couples or homes where not many hot water outlets are used at the same time.
A 26L continuous flow system is better suited to larger households or homes with stronger hot water demand. It may suit homes with more bathrooms, higher shower use or customers replacing an existing 26L gas continuous flow unit.
As a general guide:
| Model Type | Best Suited To | Main Consideration |
|---|---|---|
| Rinnai B20 | Smaller to medium homes | Check whether 20L is enough for peak use |
| Rinnai B26 | Medium to larger homes | Check gas supply, pipe sizing and installation suitability |
The right model depends on the number of bathrooms, shower habits, incoming water temperature, gas supply, water pressure and how many outlets may be used at once.
Natural Gas vs LPG Rinnai B Series Models
Rinnai B Series systems must be ordered in the correct gas type. Natural gas and LPG are not interchangeable.
Natural gas models are designed for homes connected to a natural gas supply. LPG models are designed for bottled gas or LPG supply setups.
Choosing the wrong gas type can delay installation, require a product exchange or create extra costs. Before ordering, check whether your property uses natural gas or LPG.
Installed Today currently lists both natural gas and LPG options, including:
Rinnai Infinity B20 Natural Gas Hot Water System
Rinnai Infinity B20 LPG Gas Hot Water System
Rinnai Infinity B26 Natural Gas Hot Water System
Rinnai Infinity B26 LPG Gas Hot Water System
Who Should Choose a Rinnai B20?
The Rinnai B20 is best suited to homes that need a compact, efficient continuous flow gas hot water system without stepping up to a larger 26L model.
It may suit:
smaller homes
townhouses
units
couples
small families
lower to moderate hot water demand
homes with one main bathroom
properties replacing an existing 20L instant gas unit
customers wanting natural gas or LPG instant hot water
The B20 may not be the best fit for larger households, homes with multiple bathrooms used at once, heavy shower demand or customers expecting strong hot water flow from several outlets at the same time.
If you are unsure whether 20L is enough, compare it against 26L options in the Instant Gas Hot Water Systems category before ordering.
Who Should Choose a Rinnai B26?
The Rinnai B26 is better suited to homes with higher hot water demand. It is often chosen as a replacement for an existing 26L continuous flow system or as an upgrade from a smaller instant gas unit where the home’s gas supply and installation setup can support it.
It may suit:
medium to larger homes
families
homes with more than one bathroom
higher shower demand
rental properties needing a stronger instant gas option
customers replacing an old 26L gas continuous flow unit
homes already set up for external gas continuous flow hot water
Installed Today’s 26L Instant Gas Hot Water Systems collection is useful if you want to compare Rinnai with other 26L natural gas and LPG models.
Rinnai B Series Key Features
Key features of the Rinnai B Series include:
continuous flow gas hot water
natural gas and LPG model options
compact wall-mounted design
no hot water storage tank
20L and 26L model choices
temperature preset options depending on product selection
strong brand recognition
external installation design on typical residential models
suitability for replacing many older gas continuous flow systems
compatibility with selected controllers and accessories depending on model and setup
The main practical benefit is that you only heat water when hot water is being used. There is no large storage tank constantly holding hot water.
Long-Term Use: What Homeowners Usually Notice
In long-term use, the main benefit of a Rinnai B Series instant gas system is consistent hot water when the system is correctly sized and the property’s gas and water supply are suitable.
Homeowners usually notice:
compact installation compared with storage tanks
steady hot water when sized correctly
no stored tank heat loss
good fit for natural gas homes
LPG options for properties without natural gas
less ground space needed than storage hot water
dependence on correct gas supply and water pressure
importance of professional installation and servicing
The most common problems usually come from incorrect sizing, wrong gas type, poor gas supply, water pressure issues, old pipework, blocked filters, controller settings or installation issues rather than the brand alone.
Rinnai B Series Running Costs
A Rinnai B Series instant gas system can be efficient because it heats water on demand. Unlike gas storage hot water, it does not keep a full tank hot throughout the day.
Running costs are affected by:
gas type
gas tariff or LPG bottle cost
number of people in the home
shower length
number of bathrooms
water temperature setting
incoming cold water temperature
flow rate
how many outlets are used at once
system size
maintenance condition
Natural gas and LPG running costs can differ significantly. LPG can be more expensive depending on bottle pricing, usage and delivery arrangements. Natural gas may be more convenient where the property is already connected.
Before ordering, check whether gas hot water still makes sense for the property compared with electric, heat pump or storage alternatives in the full Hot Water Systems range.
Rinnai B Series vs Gas Storage Hot Water
A Rinnai B Series continuous flow unit and a gas storage hot water system work differently.
A gas storage system heats and stores hot water in a tank. It can be simple and familiar, but it takes up more space and can have standing heat loss because stored water is kept hot.
A Rinnai B Series continuous flow system heats water only when a tap or shower is turned on. It is compact, wall-mounted and does not store a full tank of hot water.
| Feature | Rinnai B Series Instant Gas | Gas Storage Hot Water |
|---|---|---|
| Hot water method | Heats as water flows | Heats and stores water |
| Size | Compact wall-mounted unit | Larger tank |
| Running cost potential | Efficient when used correctly | Can have standing heat loss |
| Recovery | Continuous while gas/water supply suits | Limited by stored tank and recovery |
| Best suited to | Homes wanting compact continuous flow | Homes wanting traditional storage gas |
For many homes, continuous flow gas is a practical upgrade from old gas storage, but the gas supply and pipework still need to be checked.
Rinnai B Series vs Electric Storage Hot Water
The Rinnai B Series is very different from electric storage hot water.
Electric storage systems use electricity to heat and store water in a tank. They can be simple and suitable for homes without gas, but running costs can be higher unless tariffs, solar or system setup make them more affordable.
Rinnai B Series systems use gas and heat water as required. They can suit homes already using natural gas or LPG, especially where the customer wants a compact wall-mounted system instead of a storage tank.
| Feature | Rinnai B Series Gas | Electric Storage |
|---|---|---|
| Energy source | Natural gas or LPG | Electricity |
| Storage tank | No | Yes |
| Space needed | Compact wall-mounted unit | Tank space required |
| Hot water supply | Continuous while properly supplied | Limited by stored volume |
| Installation needs | Gas supply and external placement | Electrical supply and tank location |
The right choice depends on whether the property has gas, how much hot water is used, available space, running cost expectations and installation requirements.
Rinnai B Series vs Heat Pump Hot Water
A heat pump hot water system may offer lower running cost potential than gas in some homes, especially where rooftop solar is available. However, heat pumps need outdoor space, airflow, drainage and make fan/compressor noise while running.
A Rinnai B Series instant gas system may suit homes that already have gas, want a compact wall-mounted unit and prefer continuous flow hot water instead of a storage tank.
A heat pump may suit homes wanting to move away from gas, use rooftop solar during the day, or reduce electricity use compared with standard electric storage.
There is no single best option for every home. Compare gas, electric and heat pump options in Installed Today’s Hot Water Systems range before deciding.
Rinnai B Series vs Rheem and Dux Instant Gas Systems
Rinnai, Rheem and Dux all offer instant gas hot water options. The best choice depends on the model, size, gas type, warranty terms, installation setup, price and availability.
Rinnai is often chosen for brand recognition, continuous flow experience and a strong range of gas hot water products. Rheem and Dux can also be practical options depending on the property and budget.
When comparing instant gas systems, check:
flow rate in L/min
natural gas or LPG model
temperature preset options
warranty terms
product dimensions
installation requirements
minimum flow rate
controller compatibility
brand support
price
whether supplied-and-installed is available
Do not choose only by brand name. Choose the model that suits the home’s gas supply, water demand and installation location.
Supply Only vs Supplied and Installed
Installed Today offers supply-only ordering for customers who already have their own licensed installer arranged. Supply-only pricing is for the product only and does not include installation, valves, gas work, electrical work, pipework changes, drainage work, removal, disposal, wall mounting changes or compliance upgrades unless those options are clearly selected or shown on the product page.
Supplied-and-installed options may be available on selected products in eligible Brisbane and Gold Coast service areas. Availability depends on the product, location, gas type, access, existing setup, gas supply, pipe sizing, required extras and site requirements.
Before ordering supply only, make sure your licensed installer has confirmed the correct gas type, model size, installation location, pipe sizing, water pressure, controller requirements and compliance needs.
Brisbane and Gold Coast Buying Context
For Brisbane and Gold Coast homes, Rinnai B Series instant gas hot water systems can be a practical option where the property already has natural gas or LPG and a suitable external installation location.
Local homes should check:
whether the property has natural gas or LPG
whether the existing unit is 16L, 20L or 26L
whether the old system supplied enough hot water
whether the gas supply can support the selected model
whether pipe sizing is suitable
whether the installation location meets clearance rules
whether a tempering valve or controller changes are needed
whether supplied-and-installed is available for the address
whether supply-only is preferred because a licensed installer is already arranged
A 26L model is not automatically the right choice just because it is larger. If gas supply or pipe sizing is not suitable, performance may not match expectations.
Common Rinnai B Series Issues to Watch For
Common issues with instant gas systems can include:
no hot water
hot water cutting in and out
temperature fluctuation
low flow problems
controller issues
gas supply problems
blocked inlet filters
incorrect gas type
undersized pipework
fault codes
water pressure problems
installation clearance issues
Many problems are site-related rather than product-related. A licensed gas fitter should inspect gas supply, pipe sizing, installation clearances, fault codes and combustion-related issues.
Homeowners should not attempt gas hot water repairs themselves.
Maintenance and Reliability
Rinnai B Series systems are designed for long-term use, but they are not maintenance-free.
Maintenance considerations include:
keeping the unit clear of obstructions
checking for visible leaks
watching for error codes
not ignoring temperature fluctuation
arranging professional servicing when needed
checking controller operation
checking inlet filters if advised by a licensed technician
ensuring ventilation and clearances remain suitable
having gas work performed only by licensed professionals
Regular servicing can help identify problems before they turn into system failure, especially on older units or properties with water quality, gas supply or flow issues.
Before Ordering Checklist
Before ordering a Rinnai B Series instant gas system, check:
whether the property uses natural gas or LPG
whether the existing unit is 16L, 20L or 26L
whether the old unit supplied enough hot water
how many bathrooms the home has
how many outlets may run at once
whether the installation location is external and suitable
whether controller changes are needed
whether pipe sizing is adequate
whether gas supply is suitable
whether water pressure is suitable
whether supplied-and-installed is available
whether your installer has confirmed product suitability
This helps avoid ordering the wrong gas type, wrong flow rate or wrong model for the property.
Is the Rinnai B Series Worth It?
The Rinnai B Series is worth considering if you want a compact gas continuous flow hot water system from a well-known brand and your property already suits gas hot water.
It is a good option when:
you are replacing an older instant gas unit
you want continuous flow gas hot water
you have natural gas or LPG available
you want a compact wall-mounted system
you do not want a storage tank
the existing gas supply and pipework are suitable
you choose the correct 20L or 26L model for your household
It may not be the right option if:
your property does not have gas
you want to move away from gas
your household is better suited to a heat pump
your gas pipework needs major upgrades
you need the lowest possible running cost with rooftop solar
you want a storage-style hot water system
the installation location does not meet requirements
For many gas-connected homes, the Rinnai B Series remains a practical and familiar instant gas hot water option.
Long-Tail FAQs
Is the Rinnai B20 big enough for a family?
The Rinnai B20 can suit smaller to medium households with moderate hot water use. It may not be enough for larger families, multiple bathrooms running at once or homes with high shower demand. If the old 20L unit struggled, moving to another 20L system may not solve the issue.
Should I choose Rinnai B20 or Rinnai B26?
Choose the Rinnai B20 for smaller or moderate-demand homes where a 20L system suits the usage. Choose the Rinnai B26 for higher-demand homes, larger families or properties replacing an existing 26L system. The final choice depends on gas supply, water pressure, pipe sizing and household demand.
Can I replace my old Rinnai instant gas system with a new B Series model?
In many cases, yes, but the installer must check gas type, pipe sizing, clearances, water connections, controller wiring, tempering requirements and compliance. A like-for-like replacement can still need extra work if the site no longer meets current requirements.
Is Rinnai B Series natural gas the same as LPG?
No. Natural gas and LPG models are different and must be ordered correctly. The wrong gas type should not be installed. Always confirm the property’s gas supply before ordering.
Does the Rinnai B Series provide unlimited hot water?
A continuous flow gas system can keep heating water while gas, water and power supply remain suitable. However, performance still depends on the selected model size, flow rate, incoming water temperature and how many outlets are used at the same time.
Is a Rinnai B26 suitable for two bathrooms?
A Rinnai B26 may suit many two-bathroom homes, but the result depends on actual usage, simultaneous outlets, shower flow rates, gas supply and incoming water temperature. A licensed installer should confirm whether a 26L model suits the home.
Can I buy Rinnai B Series supply only?
Yes. Supply only is suitable if you already have your own licensed installer arranged. The product price is for the unit only and does not include installation, valves, gas work, electrical work, pipework changes, disposal or compliance upgrades unless selected separately.
Can I order Rinnai B Series supplied and installed?
Supplied-and-installed options may be available on selected Rinnai B Series products in eligible Brisbane and Gold Coast service areas. Availability depends on the product, address, access, gas type, existing setup, pipe sizing and required extras.
Final Word
The Rinnai B Series instant gas hot water range is a strong option for homes wanting compact continuous flow gas hot water from a recognised brand. The B20 can suit smaller to medium households, while the B26 is better suited to higher-demand homes that need more hot water flow.
The most important step is choosing the correct gas type and flow rate. Natural gas and LPG are different, and a 20L or 26L system should be selected based on household demand, not guesswork.
Browse the Rinnai Infinity B26 Natural Gas Hot Water System, Rinnai Infinity B26 LPG Gas Hot Water System, Rinnai Infinity B20 Natural Gas Hot Water System, Rinnai Infinity B20 LPG Gas Hot Water System, or compare more options in Installed Today’s Instant Gas Hot Water Systems range before ordering.
