Rinnai INFINITY® A-Series internal and external

Endless hot water, anytime



A16 $1,509, A20 $1,711, A24 $1,915, A26 $2,006, A28i $2,674

Only on when you need hot water

The Rinnai INFINITY A-Series are continuous flow hot water systems for residential applications. These water heaters produce endless hot water, and unlike electric cylinders, are energy efficient as they are only on when you need hot water.

There are five models to choose from depending on your hot water needs. Model numbers represent hot water capacity, for example the A26 produces 26 litres of hot water per minute at a 25 ° Celsius rise.

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Product Details

Suitable for
- external residential applications only (A16-A26)
- internal residential applications only (A28i)
- mains and medium pressure systems
- as a gas boost for solar connections (A28i model only1)

Hard or acidic water will need to be treated to use this product.

Not suitable
- as a spa or swimming pool heater
- for hydronic applications

1 Only unit that can be preset to 75 °C

Technical Specifications



Preset temp.

55 °C



*A28i model efficiency is 83.5%
Gas type

Available for Natural Gas or LPG, specify at the time of purchase

Available fixed temperatures

40, 42, 50, 55, 60, 65 °C (70, 75, 85 °C*)
* A28i model only

Codes and REU numbers
  • A16: INFA16N/L, REU-A1620WG-ZK
  • A20: INFA20N/L, REU-A2024WG-ZK
  • A24: INFA24N/L, REU-A2426WG-ZK
  • A26: INFA26N/L, REU-A2626WG-ZK
  • A28i: INFA28FFN/L, REU-VCM2837FF-ZK
Hot water capacity
  • A16: 1.5-16 L/min
  • A20: 1.5-20 L/min
  • A24: 1.5-24 L/min
  • A26: 1.5-26 L/min
  • A28i: 1.4-37 L/min
Input and output
Model Input MJ/h Output kW
A16 16.3-124 27.8
A20 19.9-156 34.9
A24 16.3-184 42.0
A26 16.3-199 44.5
A28i 11-210 48.8
Exhaust system
  • External units - forced flue
  • Internal unit - room sealed forced flue
Frost protection

Fitted as standard. Frost protection operates automatically, as long as the appliance is connected to the electrical power supply, by activating when the temperature inside the unit drops below 3.5 °C, and turns off once the temperature inside the unit reaches 7 °C.

Ignition system

Direct electronic ignition

Injector sizes
Model NG LPG
A16 0.9, 1.50 0.71, 1.09
A20-A26 1.08, 1.80 0.73, 1.12
Line pressure (min.)

NG - 1.13kPa, LPG - 2.75 kPa

Line pressure (max.)

3.5 kPa (maximum standing pressure under abnormal intermittent conditions is 5.0 kPa).

In the case of commercial metering, (i.e. 35-37 kPa coming in), there may be a requirement to regulate the incoming pressure down.

Power consumption
  • Normal: 47 W (A16), 58 W (A20), 56 W (A24), 66 W (A26), 95 W (A28i)
  • Standby: 2 W
  • Automatic frost protection: 68 W (A16-A26), 120 W (A28i)
Pressure relief

Valve opens at 2060 kPa, closes at 1470 kPa

Water supply

Nominal operating pressure: 

  • A16: 120-1000 kPa
  • A20: 160-1000 kPa
  • A24: 200-1000 kPa
  • A26: 200-1000 kPa
  • A28i: 220-1000 kPa

Minimum operating water flow will depend on setpoint and inlet temp.

Noise level

External units 50 dB(A), internal unit 54 dB(A). Some people are susceptible to low level noise. This needs to be considered if locating an appliance near a bedroom.

Safety devices
  • Flame failure
  • Boil-dry protection
  • Overheat protection
  • Fusible link
  • Pressure relief valve
  • Combustion fan RPM check
  • A16: 13 kg
  • A20: 14 kg
  • A24/A26: 15 kg
  • A28i: 21 kg

Energy Safety Supplier Declaration of Compliance declaration numbers:

  • A16 - 1825920179
  • A20 - 1825820179
  • A24 - 1825720179
  • A26 - 1825620179
  • A28i - DEC-000001841X8M7
Market release

A16-A26: 2018
A28i: Dec 2021

MasterSpec link

CAD/BIM Downloads


We recommend that Rinnai gas appliances are serviced every two years. This can extend the operating life of your appliance, and also ensures it is running at peak efficiency - saving you and your family money. To book a service, phone 0800 RINNAI (0800 746 624) or fill in our form online.

  • As the world’s largest gas appliance manufacturer, Rinnai is widely regarded as the industry leader.
  • Rinnai products are known throughout the world for their superior quality, safety, technology and sophisticated control systems, all factories are ISO 9001 and/or ISO 14001 certified.
  • We have an established 40 year history in New Zealand.
  • Rinnai are happy to advise that we now have an IANZ accredited Test Lab for MEPS testing on Hot Water Cylinders. The lab uses the latest in test equipment and can test all type of Hot Water Cylinders for MEPS heat loss testing.

We realise there's a lot of information out there. Water heating is important and it's better to spend the time up front deciding on what you need and what's important.

We have an experienced customer service team that can walk you through the process. For those more complicated projects we also have a free specification service. Give us a call: 0800 RINNAI (0800 746 624)

They are both continuous flow water heaters but the Rinnai efficiency is the latest generation of water heater with an efficiency of at least 92% or more, compared to 80% of the standard Rinnai INFINITY®. The Rinnai efficiency has an additional heat exchanger. The second heat exchanger enables the efficiency range to extract even more heat from the gas, meaning less energy is required to meet your hot water requirements.

Digital controllers allow you to select the exact temperature of the hot water at the outlet. This has a number of benefits: 

  • Safety, especially if you have young children, the hot water can be pre-set to a child-safe level
  • No need to mix hot and cold water, this reduces the changes in water temperature when another tap in the building is turned on
  • You use your continuous flow unit more efficiently as less gas is required to heat water to 40 °C (typical shower temperature) than at 55 °C (which is the default temperature without controllers)
  • Highlights any problems (disruption in gas supply etc.) by displaying error codes on the controller

Installation costs are difficult to provide as every installation is different. Factors such as the length of pipe required, whether you have accessories fitted, how far away you live and choosing an internal or an external unit all influence the overall cost.

If you’re interested in a Rinnai hot water heating solution, we highly recommend you contact a plumber/gas fitter who will be able to explain all the options to you.

A 9.0 kg cylinder is only capable of delivering a max of around 19mJ/hour.  A Rinnai INFINITY® A26 requires 199mJ/hour. Inadequacy of gas supply will cause frequent error code 11 and the appliance will fail.

The gas from a 9kg bottle is likely to be very dirty and this residue has the potential to block/congest the gas valve and damage the appliance.  As the 9kg bottle will not provide an adequate supply of gas for the appliance, the installation is not compliant. When an appliance is being run in a non-compliant (with the NZ regulations) installation, Rinnai will not accept any warranty on the product.