Rinnai HydraHeat® Split Hot Water Heat Pump

A solution for new and existing cylinders

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

This energy-efficient split 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.

The Rinnai HydraHeat® Split Hot Water Heat Pump utilises thermal stratification within the storage cylinder to ensure rapid hot water delivery from the moment it starts, offering an efficient and practical water heating solution.

Product Details

	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** By maximising energy output while minimising input, the HydraHeat® Split Hot Water Heat Pump ensures reliable, cost-effective hot water heating, making it an ideal choice for energy-conscious households.
	Faster Top-Down Heating The HydraHeat® Split system delivers hot water directly to the top of the cylinder from startup, delivering instant hot water right when you need it.
	Dedicated to Sustainability Uses only 150gm nominal charge of R290 natural refrigerant.
	Frost Protection Built-in defrost and frost protection functions to handle colder climates.
	4 Operation Modes Eco 55, Standard, Element Only and Shutdown.

	Timer Function Allows you to schedule heating cycles to align with your solar PV system’s peak generation or off-peak electricity rates. This maximises energy efficiency and cost savings by ensuring your hot water is heated when electricity is most affordable or renewable energy is readily available.
	Quiet Operation Quiet operation to ensure noise comfort for both you and your surrounding neighbours.
	Ease of Installation The outdoor compressor unit allows for ambient air to efficiently heat the water and is ideal for homes with inside space restraints.
	Split Design – for easy retrofit to your current cylinder*** Allows you to enhance your current hot water heating solution without the need to replace your current cylinder.
	Warranty – 5 years 5-year heat pump module warranty.
	Modern Design Cod Grey colourway for modern aesthetics.

^{* When a comparison calculation is made to a 250L standard electric hot water cylinder when heating water from 19°C to 55 °C.}^{** Coefficient of Performance was measured at the following conditions: Inlet water temperature 19°C, Outlet Water temperature 55°C, Dry Bulb Temperature 19°C.}^{*** Please refer to our cylinder compatibility checklist to find out if your cylinder is compatible with the HydraHeat® Split system.}

Product description

The Rinnai HydraHeat® Split External Unit is designed for outdoor installations.

Scope of use

Retrofit or new build residential applications.
Connection to a compatible indoor/outdoor cylinder.

Not suitable as a spa or swimming pool heater, or for hydronic applications. Hard and acidic water will need to be treated to use this product, refer water quality parameters in the support material (downloads).

Tech Specs
Downloads

Tech Specs

Technical Specifications

Model number / order code

RHPN361S

Cylinder compatibility criteria

The cylinder to which the HyrdaHeat Split is connected must meet all the following criteria. If you are unsure, an onsite inspection is recommended. Warranty does not cover connections to incompatible cylinders.

Single element¹ mains pressure cylinder, 180-340 L, element size 3 kW or less
A Rinnai, HJ Cooper, or Rheem cylinder that is eight years old or less
A cylinder not connected to supplementary heating (e.g. wetback, solar thermal etc)
A cylinder with a suitable TPR (rated 10 kW or more)
Pipe run length is less than 20 m (supplied cable is 15 m, extension cable is 5 m)
Difference in height between base of cylinder and base of heat pump no more than 5 m
Adequate clearance to install cylinder connections (relates indoor cylinders)
Minimum water pressure of 100 kPa
ECV of no more than 700 kPa must be present or fitted
Cylinder thermostat set to 70 °C, this temperature is required to ensure Element only’ mode and Legionella disinfection cycles function correctly

¹ _{Cylinder element must be operational and properly connected, as it is essential for both the operation and compliance of Legionella disinfection.}

Coefficient of performance (COP)

4.6
(inlet water temp 19 ºC, outlet water temp. 55 ºC, ambient temp. 19 ºC)

_{Accredited Testing to AS/NZS 5125 by NATA accredited Provider}

Outlet water temperature

Standard: 60 °C, Eco 55 °C

Storage capacity

Will be based on the cylinder it is connected to

Maximum valve pressure settings

TPR (required): Refer manutacturer’s specification
Cold water expansion valve: 700 kPa (must be installed)
Pressure limiting valve: 500 kPa

Rated heat pump input/output

765 W / 3600 W

Hot water recovery rate

86 L/h
Recovery rate is calculated at Eco 55 mode, 19 ºC ambient temp., 36 ºC rise.

Max. current (heat pump standard mode)

4.6 A

Max. current heat pump (element only)

14.5 A

Backup resistance element rating capacity

3000 W

Min. inlet water pressure

100 kPa

IP rating

IP24

Water port connections

G½ ” (15 mm x 2)

Sound pressure level at 1 m

48 dB(A)

_{Sound pressure measured at 1m distance from water heater in free field. Appliance operated in standard mode (60 °C) at an ambient temperature of 19 °C}

Power supply

230-240 V 50 Hz

Dimensions

Height: 750 mm
Width: 835 mm
Depth: 365 mm

Weights

Net: 42.5 kg, Gross: 50 kg

Data label position

Behind front cover, positioned on panel between compressor and fan

Refrigeration type

R-290 / 150 g

Accessory - touch up paint

R1886: Touch up paint cod grey – 400 ml aerosol can

Accessory - 5 m extension cable

R1012: HydraHeat Split extension cable 5 m

The supplied cable for the cylinder connection is 15 m. If the distance between the heat pump unit and cylinder is longer than 15 m, a 5 m extension cable is available.

Market release

April 2025

Downloads

HydraHeat Split Brochure

HydraHeat Split operation guide

HydraHeat Split installation guide

HydraHeat Split quick start install guide

HydraHeat Split Supplier Declaration of Conformity (SDoC)

HydraHeat Split exploded diagram and spares

HydraHeat Split warranty

FAQs

A split system separates the heat pump unit and the hot water cylinder, usually with the heat pump unit outside and the cylinder installed indoors. It provides more flexibility, especially in homes where space is tight. An integrated system combines both the heat pump and tank into one tidy outdoor unit. It’s simple to install and ideal if you’ve got the room outside. Both are energy efficient – your choice depends on your home’s layout and how you like things set up.

A hot water heat pump works with a cylinder or storage tank to store heated water. The heat pump draws warmth from the air and transfers it to the water stored in the tank. Rinnai’s integrated hot water heat pump models come with their own cylinders, but you can connect an existing cylinder with our HydraHeat® Split hot water heat pump.

Hot water heat pumps, sometimes called hybrid heat pumps or heat pump water heaters, are designed to efficiently heat water for domestic and commercial use. They operate on the same principle as air source heat pumps, which extract heat from the surrounding air. This warms the water in the cylinder which is then supplied into your home or commercial space.

Hot water heat pump systems should be serviced every two years. Installation, servicing, repair, and removal shall be carried out only by authorised personnel. They require minimal maintenance, primarily involving occasional checks and cleanings. This ease of maintenance adds to their appeal for both homeowners and businesses.

While hot water heat pumps offer long-term savings, the initial investment can be higher compared to traditional water heaters. It can cost upwards of $4,000 for the unit alone, and then more for proper installation from an experienced technician. This ensures that the heat pump is the correct size, placed correctly, and integrated with the existing plumbing.

Hot water heat pumps are regarded as the most environmentally friendly hot water solution in the market. They use heat in the air, reducing greenhouse gas emissions and dependence on fossil fuels. This makes them a viable choice for environmentally conscious individuals and organizations striving to minimize their carbon footprint.

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Rinnai HydraHeat® Split Hot Water Heat Pump

Downloads

Gallery

A solution for new and existing cylinders

Product Details

Tech Specs

Technical Specifications

Downloads

FAQs

What’s the difference between a split and integrated hot water heat pump?

Do I need a hot water cylinder or tank with a heat pump?

How does a hot water heat pump work?

How often do hot water heat pumps need maintenance?

How much does it cost to install a hot water heat pump?

Are hot water heat pumps environmentally friendly?

From our blog

Why Rinnai?

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