Rinnai INFINITY® NB-Series Internal and External

The Rinnai INFINITY® NB-Series high-efficiency gas continuous flow water heaters are designed for commercial applications and high demand residential installations.

Specs

Codes / REU number

NB56kWe external (REU-NB3237WC-ZK)
Code:  INFNB56S

NB56kWi internal (REU-NB3237FFC-ZK)
Code: INFNB56FFS

Gas type

NG or ULPG
The NB-Series models are universal, allowing the gas type to be configured during installation through the commissioning process.

Colour

Silver

Factory preset temperature

The INFINITY NB-Series units are preset to 50 °C. They can be set to deliver higher temperatures, up to 85 °C, making them ideal for commercial applications.

Hot water capacity

1.0-42 litres per minute. Nominal water capacity is 32 litres per minute at a 25 ºC rise (1920 L/h)

Exhaust system

• External unit – 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

Ingress protection rating

IPX5

Line pressure (min.)

NG – 1.13kPa, LPG – 2.75 kPa

Standing and flowing pressure must be less than 3.0 kPa.

Power consumption

• Normal: 92 W (NG), 98 W (LPG)
• Standby: 2.3 W
• Automatic frost protection: 140 W

Water supply

Nominal operating pressure: 300-1000 kPa
Minimum operating water flow will depend on setpoint and inlet temp.

Noise level

Internal model 46 dB(A), external model 56 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
• Pressure relief valve
• Combustion fan RPM check

Weight

• 25 kg – NB56kWi internal
• 27 kg – NB56kWe external

Compliance

Energy Safety Supplier Declaration of Compliance: Declaration number – DEC-000002866T1F3

Market release

March 2025

Features

Condensing technology
Utilises a secondary heat exchanger to drive further thermal efficiency by extracting heat from combusted flue gases, making the NB-Series models 97% efficient.

Suitable for

• External commercial and residential applications (NB56kWe external model only).
• Internal commercial and residential applications (NB56kWi internal model only).
• Mains and medium pressure systems. Hard or acidic water will need to be treated to use this product.

Not Suitable for

• As spa or swimming pool heater
• For hydronic applications