Hot Water Heat Pump NZ: 6 Honest Checks on Cost and Size

Hot water heat pump NZ costs are higher upfront: EECA puts a typical system at about $7,000 installed, against about $4,000 for a new electric cylinder. In return it uses around 60 to 75% less electricity, and EECA estimates about $180 a year to run instead of $480. It heats water with warmth taken from the outside air.

How a hot water heat pump works

It is the same idea as the heat pump on your lounge wall, pointed at a tank of water. A fan draws outside air over a coil, the refrigerant picks up that heat, a compressor lifts its temperature, and the heat passes into the water. EECA gives a coefficient of performance (COP) of around 2 to 4, meaning 1 kWh of electricity puts 2 to 4 kWh of heat into the water. A plain electric element sits just under 1.

There are two layouts:

• Integrated (all in one): the heat pump sits on top of the cylinder and the whole unit goes outside. Consumer NZ notes these are quicker and a little cheaper to install, and there is more choice.
• Split: an outdoor heat pump joined to a cylinder that can be inside or out. More flexible on placement, and EECA says the outdoor unit can sometimes be fitted to an existing cylinder that is in good condition.

Hot water heat pump NZ cost: buying, installing and running

EECA’s homeowner pages give these round numbers for an average home. They include purchase and installation.

EECA’s savings calculator puts the saving at around $284 a year for a 3 person Auckland household moving from an electric cylinder to a heat pump. Your number will depend on your power price, your climate and how much hot water you use.

Real quotes vary a lot. In EECA’s 2025 field trial, 84 homes had systems fitted. The units alone ranged from $1,900 to $7,800 (average $5,800) and installation from $1,600 to $9,500, both excluding GST. Installs in the coldest zone averaged about $5,600, around $1,500 more than warmer parts of the country, and two complex jobs with quotes nearing $15,000 to $20,000 were not done. One Consumer NZ tester paid $8,505 installed and found less than half of that was the unit itself.

So when you compare quotes, split them into the unit price and the labour. Labour moves with how far the new unit sits from the old cylinder, the pipe runs and whether the switchboard needs work.

What size hot water heat pump do you need?

EECA’s good practice installation guide (November 2025) uses bedrooms as a starting point for daily hot water demand:

Demand is not the same as tank size. EECA gives the example of a 250 L cylinder that could deliver 300 L a day with some cold water being heated as it goes, or cover a 200 L day with a safety margin. Then adjust for baths, a washing machine on hot, or teenagers who shower for 20 minutes. MBIE’s Smarter Homes guide says a family of four typically needs at least 180 litres of storage.

Do not go too big either. EECA’s trial found that for homes using under 100 L a day, many units on the NZ market are oversized, and the extra stored water loses heat and drags efficiency down. Too small, and Consumer NZ’s warning applies: cold showers.

Is a hot water heat pump worth it in your home?

EECA lists the homes that get the most out of one:

• Bigger households with steady hot water use. More hot water means more savings to pay back the higher price.
• Standalone houses with outdoor space and simple plumbing.
• New builds, where room for the unit can be planned from the start.
• Homes with underfloor heating or radiators, as some systems can heat those too.

EECA’s installer guide is blunt about the other end: one or two people, or very low hot water use, are unlikely to save enough to justify the purchase. The trial also found swapping an outdoor gas instant heater was the easiest job, because power and plumbing were already outside. Replacing an indoor cylinder was harder, and some homes found hot water took longer to reach the taps.

Timing matters as well. If your cylinder is nearing the end of its life (EECA uses 15 years), plan the switch now. Waiting until it fails leaves you taking whatever can be fitted that week.

6 checks before you buy

1. Cold weather output. MBIE says these units work best above 6 to 7°C and lose efficiency as it gets colder. Ask for the heat output at 2°C outside air. In EECA’s trial, early results put CO2 and R32 units ahead and R134a units last.
2. Power supply. EECA’s guide says a unit typically draws around 0.9 kW, and a booster element another 1.5 to 3.5 kW. Get an electrician to check the switchboard and wiring, as Consumer NZ also advises.
3. Noise and position. EECA puts the noise at around 40 to 55 dB, about a library to moderate rain. Keep it away from bedroom windows, including the neighbours’.
4. Space and drainage. The outdoor unit needs airflow, a level base and somewhere for condensate to drain, close to the kitchen, bathroom and laundry to keep pipe runs short.
5. Building consent. EECA’s guide says replacing an existing water heater with a heat pump unit is generally exempt, but the work must still be done by an authorised plumber and meet the Building Code. Adding a heat pump to an existing cylinder, rather than replacing it, may need consent, so check with your council.
6. Temperature settings. The cylinder is typically kept at 60°C or more to prevent Legionella, with a tempering valve so water at the bathroom taps stays around 45 to 50°C.

Energy ratings will not help you compare yet. Consumer NZ points out that hot water heat pumps are not regulated for energy efficiency in New Zealand, so you cannot compare brands the way you can with space heating heat pumps.

Hot water heat pumps at NZ DEPOT

We sell complete units supply only, so your own plumber and electrician can fit them. On 10/11/2026 our prices, incl. GST, ran from $3,709.99 for a Haier 280 L split system to $4,429.99 for a Haier 330 L all-in-one, with Gree Whio TD200 and TD270 models in between. Two Haier 200 L and 250 L models come with a 15 A 3-pin plug, so they need a 15 A outlet rather than hardwiring. Delivery is usually 3 to 9 working days. Prices below are live.

See the full hot water heat pump range, or send us your number of bedrooms and people and we will suggest a size.

Hot water heat pump NZ FAQs

How much does a hot water heat pump cost in NZ?

EECA’s typical figure is about $7,000 installed. In its 2025 trial the units ranged from $1,900 to $7,800 and installation from $1,600 to $9,500, excluding GST. Our complete units were $3,709.99 to $4,429.99 incl. GST on 10/11/2026, before installation.

Do hot water heat pumps work in winter?

Yes, but they work harder. MBIE says efficiency drops as outside temperatures fall, and EECA’s trial found the best results in the warmest climate zone and the lowest in the coldest. Some units have a booster element for very cold spells.

How long does a hot water heat pump last?

EECA’s homeowner page says around 15 years. Its more detailed article gives 8 to 15 years, similar to a gas heater and a little less than a plain electric cylinder, because there are more moving parts.

Can I keep my existing cylinder?

Sometimes. EECA says the outdoor unit of a split system can be retrofitted to an existing cylinder in good condition. That job may need a building consent, so ask your council first.

Is a hot water heat pump noisy?

Around 40 to 55 dB according to EECA, which is quieter than most people expect but still noticeable at night. Place it away from bedrooms.

Related guides and products

• Hot water heat pumps (prices incl. GST)
• All hot water systems
• Heat pump running cost guide
• Heat pump finance options

Sources

• EECA, Compare common home water heating options (read from the archive copy of 07/06/2026)
• EECA, Hot water heat pumps for your home (archive copy of 07/06/2026)
• EECA Insights, Hot water heat pumps in the home (archive copy of 14/07/2026)
• EECA, Heat pump water heater good practice installation guide (November 2025)
• EECA, Heat pump water heater project interim report (December 2025)
• MBIE Smarter Homes, Hot water options (updated 09/08/2023)
• MBIE Smarter Homes, Hot water cylinders and pipes (updated 09/08/2023)
• Consumer NZ, Insider’s guide to hot water heat pumps (04/12/2025)
• NZ DEPOT catalogue prices on 10/11/2026 (the product grid above is live).