Introducing the HydraHeat® Split – a versatile solution compatible with both new and existing cylinders*.

This energy-efficient hot water heat pump is eligible for an NZ Green Energy Loan – read here for more information.

Combining Rinnai’s expertise in water heating and heat pump technology, the HydraHeat® Split Hot Water Heat Pump offers a highly efficient way to heat your water. Its split design allows flexible installation while maximising performance.

Designed and built in New Zealand, the Rinnai HydraHeat® Split Hot Water Heat Pump utilises thermal stratification within the storage cylinder to ensure rapid top-down hot water delivery from the moment it starts, offering an efficient and practical water heating solution.

*Please refer to Rinnai’s cylinder compatibility checklist to find out if your cylinder is compatible with the HydraHeat® Split system.

Details
  • Category
    Heat Pumps
  • Range
    Hot Water Heat Pump
  • Brand
    Rinnai
Key Features
  • Up to 75% Energy Savings*: Provides highly efficient water heating, minimising energy consumption and lowering operating costs.
  • High Coefficient of Performance (COP) of 4.6 – providing energy efficiency**: Maximises energy output while minimising input for reliable, cost-effective hot water heating — ideal for energy-conscious households.
  • Faster Top-Down Heating: Delivers hot water directly to the top of the cylinder from startup, ensuring hot water is available right when you need it.
  • Dedicated to Sustainability: Uses only 150g nominal charge of R290 natural refrigerant.
  • Frost Protection: Built-in defrost and frost protection functions allow operation in colder climates.
  • 4 Operation Modes: Eco 55, Standard, Element Only, and Shutdown.
  • Quiet Operation: Operates quietly for enhanced noise comfort for users and nearby neighbours.
  • Ease of Installation: Outdoor compressor unit heats water efficiently using ambient air — perfect for homes with limited indoor space.
  • Split Design – Easy Retrofit*: Can be connected to your existing hot water cylinder without requiring a full replacement.
  • Warranty – 5 Years: 5-year heat pump module warranty for peace of mind.
  • Modern Design: Cod Grey colourway offers sleek, modern aesthetics.

* When compared to a 250L standard electric hot water cylinder heating water from 19°C to 55°C. ** COP measured at: Inlet water temp. 19°C, Outlet water temp. 55°C, Dry Bulb temp. 19°C. *** Refer to the cylinder compatibility checklist to confirm compatibility with the HydraHeat® Split system.

Technical Specifications

Model Number / Order Code

  • RHPN361S

Cylinder Compatibility CriteriaThe cylinder connected to the HydraHeat® Split must meet all the following criteria (onsite inspection recommended if unsure):

  • Single element¹ mains pressure cylinder, 180–340 L, element size 3 kW or less
  • Rinnai, HJ Cooper, or Rheem cylinder that is 8 years old or less
  • Not connected to supplementary heating (e.g., wetback, solar thermal)
  • Cylinder with TPR rated 10 kW or more
  • Pipe run length < 20 m (15 m cable supplied; 5 m extension available)
  • Height difference between cylinder base and heat pump base ≤ 5 m
  • Adequate clearance to install cylinder connections (for indoor cylinders)
  • Minimum water pressure: 100 kPa
  • ECV of 700 kPa or less must be fitted
  • Cylinder thermostat set to 70 °C (required for 'Element only' mode and Legionella disinfection)

¹ Cylinder element must be operational and properly connected for compliance and Legionella protection.

Performance Specs

  • Coefficient of Performance (COP): 4.6 (Inlet water temp: 19 °C, outlet: 55 °C, ambient: 19 °C)
  • Outlet Water Temperature: Standard: 60 °C Eco: 55 °C
  • Storage Capacity: Based on connected cylinder
  • Hot Water Recovery Rate: 86 L/h (Eco 55 mode, 19 °C ambient, 36 °C rise)

Valve & Pressure Requirements

  • TPR: Refer to manufacturer’s spec
  • Cold Water Expansion Valve: 700 kPa (must be installed)
  • Pressure Limiting Valve: 500 kPa
  • Minimum Inlet Water Pressure: 100 kPa

Electrical & Power Info

  • Rated Heat Pump Input/Output: 765 W / 3600 W
  • Max Current (Standard Mode): 4.6 A
  • Max Current (Element Only): 14.5 A
  • Backup Resistance Element: 3000 W
  • Power Supply: 230–240 V / 50 Hz

Physical Specs

  • Dimensions (H x W x D): 750 mm x 835 mm x 365 mm
  • Weight: Net 42.5 kg / Gross 50 kg
  • IP Rating: IP24
  • Water Port Connections: G½” (15 mm x 2)
  • Sound Pressure Level (1 m): 48 dB(A) (Measured in standard mode @ 19 °C ambient)
  • Data Label Position: Behind front cover (between compressor and fan)

Refrigerant

  • Type: R-290
  • Charge: 150 g

Accessories

  • R1886: Touch-up paint, Cod Grey, 400 ml aerosol can
  • R1012: HydraHeat® Split 5 m extension cable (Standard 15 m cable supplied; extension required if distance exceeds 15 m)

Market Release

  • April 2025

About the
Seller

For over 45 years, Rinnai has supplied New Zealand homes with a range of appliances that help Kiwis to enjoy comfortable, safe and efficient lives. We’ve designed and manufactured products especially for New Zealand homes and conditions – from heating your water, to heating and cooling your living areas. With over a million appliances sold over this time, Rinnai has established a proud reputation for quality and reliability, and become known as your total home living experts.

At Rinnai, we’re all about comfort.

Rinnai