Rinnai INFINITY® A-Series 
internal and external


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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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

Pro Series High Wall Heat Pump Range


Colour White

Preset Temp. 55°C

Efficiency 80%*


Gas type

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

Available fixed temperatures


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


Model code and REU number 

A16: INFA16N/L, REU-A1620WG-ZK

A20: INFA20N/L, REU-A2024WG-ZK

A24: INFA24N/L, REU-A2426WG-ZK

A26: INFA26N/L, REU-A2626WG-ZK



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.

Exhaust system 

External units - forced flue

 Internal unit - room sealed forced flue


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)

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

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.



18 kg  


Ignition system

Direct electronic ignition


Energy Safety Supplier Declaration of Compliance declaration numbers:

 A16 - 1825920179

 A20 - 1825820179

 A24 - 1825720179

 A26 - 1825620179

 A28i - DEC-000001841X8M7



How often should I service my gas appliance?

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. 

There are so many similar products around, what does Rinnai provide that the others don't?

  • 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.

I'm not really clear on any option and it's all getting a bit too confusing, what should I do?

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.

For continuous flow units you promote the use of remote controllers, why?

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

I’m trying to factor costs and then compare what’s best. I can find out the cost of the different products but what about installation costs?

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.