Hot water heating accounts for approximately 30% of the average New Zealand household’s energy consumption (EECA, 2023). For homeowners looking to reduce power bills and environmental impact, switching to an energy efficient heat pump water heater is one of the smartest moves you can make.
Hot water heat pumps offer a cutting-edge, sustainable solution to traditional water heating methods. By using advanced heat transfer technology, they deliver impressive energy savings — up to 75% less electricity than conventional electric water heating systems. Rinnai, a trusted name in New Zealand home heating, offers three standout models designed specifically for local conditions: the HydraHeat® Integrated, HydraHeat® Split and the Enviroflo™ GR Series.
Understanding Hot Water Heat Pump Technology
How Hot Water Heat Pumps Work
Hot water heat pumps operate like a refrigerator in reverse — they extract heat from the surrounding air and use it to heat water. Rather than generating heat from scratch, they transfer existing heat, which is what makes them so efficient.
The core of the system is a refrigeration cycle made up of four steps:
- Evaporation – The refrigerant absorbs heat from the air and evaporates.
- Compression – The vapour is compressed, raising its temperature.
- Condensation – Heat is transferred to the water, and the refrigerant condenses.
- Expansion – Pressure drops, allowing the cycle to restart.
Unlike imported models, Rinnai’s systems are engineered specifically for NZ’s variable climate, delivering optimal performance even in cold regions.
What is a hot water heat pump? →
COP – How Efficiency is Measured
Efficiency is measured using the Coefficient of Performance (COP) — the ratio of energy output to input. A higher COP means better efficiency:
- HydraHeat® Integrated: COP 4.7
- HydraHeat® Split: COP 4.6
- Enviroflo™ GR Series: 215L COP 4.0 / 265L & 300L COP 4.1
- Electric water heating: COP ~1
- Gas systems: COP ~0.8
This means that for every 1kW of electricity used, HydraHeat® Integrated hot water heat pump produces up to 4.7kW of heat — an exceptional efficiency level. Both models maintain high performance even in temperatures as low as -10°C.
How Much Electricity Do Hot Water Heat Pumps Really Use?
Comparing Energy Usage Across Water Heating Options
So, does a hot water heat pump use a lot of electricity? In short, no. They use far less.
- Hot water heat pumps typically consume 60–75% less electricity than electric cylinders (EECA, 2023).
- The Rinnai HydraHeat® Integrated system uses just 802W input to generate 3725W of hot water output.
- The Rinnai HydraHeat® Split system uses just 765W input to generate 3600W of hot water output.
- The Rinnai Enviroflo™ GR Series systems use 1100W input to generate 3300W of hot water output.
In contrast, traditional systems may have similar power ratings (1.8–3.6kW) but operate much less efficiently.
Power Ratings Explained: 1.8kW vs 3.6kW Systems
Power ratings indicate maximum output, not constant usage. A 3.6kW system like the Enviroflo™ GR Series doesn’t draw 3.6kW continuously — its actual energy consumption is much lower due to efficient heat transfer.
Choosing the right size depends on:
- Household size
- Daily hot water usage
- Desired recovery rate
The Economics of Hot Water Heat Pumps in New Zealand
Initial Investment vs. Long-Term Savings
While upfront costs are higher, the long-term savings are substantial:
- HydraHeat® Integrated 275L: $6,499
- HydraHeat® Integrated 340L: $6,750
- HydraHeat® Split: $4,299
- Enviroflo™ GR: 215L $4,119
- Enviroflo™ GR: 265L $4,499
- Enviroflo™ GR: 300L $5,339
With typical energy savings, most NZ households can expect a payback period of 5–7 years. And for high-use households, savings are even more significant.
You may also be eligible for a Green Energy Loan to help offset the initial cost.
Hot water heat pump installation cost →
Annual Running Cost of a Hot Water Heat Pump
| Household Size | Annual Cost Electric | Annual Cost Heat Pump | Annual Savings |
| 2 People | $800 | $250 | $550 |
| 4 People | $1,200 | $400 | $800 |
| 6 People | $1,500 | $500 | $1,000 |
(Source: Gen Less, 2023)
Environmental Benefits: Reducing Your Carbon Footprint
Over 15 years, switching from gas to a heat pump could reduce your household CO₂ emissions by around 7,000kg (A2W Plumbing, 2024).
All Rinnai models use eco-friendly R290 refrigerant with ultra-low Global Warming Potential (GWP):
- HydraHeat® Integrated: 150g refrigerant
- HydraHeat ® Split: 150g refrigerant
- Enviroflo™ GR: 215L 380g refrigerant / 265L & 300L 395g refrigerant
Coupled with NZ’s 80% renewable electricity supply, hot water heat pumps offer one of the greenest heating solutions available.
Which Homes Benefit Most from Hot Water Heat Pumps?
Hot water heat pumps are perfect for:
- Larger households with high daily water demand
- Standalone homes or new builds with suitable outdoor space
- Eco-conscious homeowners wanting long-term cost and carbon savings
HydraHeat® Integrated 275L: Suitable for 2-5 people
HydraHeat® Integrated 340L: Suitable for 2-7 people
HydraHeat® Split: Dependant on cylinder size
Enviroflo™ 215L: Suitable for 2-4 people
Enviroflo™ 265L: Suitable for 2-5 people
Enviroflo™ 300L: Suitable for 2-6 people
All models operate quietly (45-48dB) and efficiently in all NZ climates.
Installation Considerations
- Space required
- Installation location
- Piping & wiring layout
- Qualified installers
Rinnai’s Advanced Hot Water Heat Pump Range
Rinnai HydraHeat® Integrated: Premium Efficiency
- NZ-designed and assembled
- Outstanding 4.7 COP
- Six operating modes: Standard, Boost, Eco 55, Eco 50, High Usage, Element Only
- Quiet and powerful performance down to -10°C
- Hot water recovery rate: 89L/h
- Excellent warranties: 5-year heat pump, 7-year cylinder
Explore HydraHeat® Integrated →
Rinnai HydraHeat® Split: A Solution for New & Existing Cylinders
- NZ-designed and manufactured
- Split design for easy retrofit to an existing cylinder*
- Outstanding 4.6 COP
- Four operating modes: Standard, Eco 55, Element Only, Shutdown
- Quiet and powerful performance down to -10°C
- Excellent warranty: 5-year heat pump module
* Please refer to our cylinder compatibility checklist to find out if your cylinder is compatible with the HydraHeat® Split system.
Rinnai Enviroflo™ GR Series: Entry-Level Efficiency
- Cost-effective option starting at $4,119
- Choice of 215L, 265L or 300L to suit your hot water needs
- 4.0/4.1 COP and approximately 66L/h recovery rate
- Built-in frost protection
- Operating range: -7°C to +45°C
- Excellent warranties: 3-year heat pump parts, 7-year cylinder parts
Making the Right Choice: Is a Hot Water Heat Pump Right for You?
To determine the best option, consider:
- Household size and hot water usage
- Outdoor space availability
- Upfront budget vs. long-term savings
- Environmental impact goals
Choose HydraHeat® Integrated for top-tier efficiency and future-ready modular design. Opt for HydraHeat ® Split for flexibility of use with new or existing* cylinders. Or choose Enviroflo™ GR if you want excellent performance and affordability.
* Please refer to our cylinder compatibility checklist to find out if your cylinder is compatible with the HydraHeat® Split system
Frequently Asked Questions
Will I have enough hot water for my family?
Yes. Both HydraHeat® and Enviroflo™ are sized for common household needs, with fast recovery rates.
How does weather affect hot water heat pump performance?
Rinnai systems are designed for NZ climates, working efficiently down to -10°C (HydraHeat®) and -7°C (Enviroflo™ GR).
What maintenance is required?
Minimal. Regular servicing ensures optimal performance, and Rinnai’s systems are designed for easy maintenance.
Can I retrofit a heat pump to my existing system?
Yes, especially with Rinnai’s modular designs. Speak to an authorised installer for site-specific advice.
How does a hot water heat pump compare to solar?
Heat pumps are more consistent year-round, especially in cloudy or cooler regions.
Do they work well during New Zealand winters?
Yes. Unlike many imported units, Rinnai heat pumps are designed specifically for New Zealand conditions.
What size do I need?
Choose a size based on household size:
- HydraHeat® Integrated 275L: Suitable for 2-5 people
- HydraHeat® Integrated 340L: Suitable for 2-7 people
- HydraHeat® Split: Dependant on cylinder size
- Enviroflo™ 215L: Suitable for 2-4 people
- Enviroflo™ 265L: Suitable for 2-5 people
- Enviroflo™ 300L: Suitable for 2-6 people
Take the next step:
Book a free consultation or find your nearest installer →
Prices and product information correct as per July 2025
