A smarter way to heat and store your hot water
A hot water heat pump uses the same basic idea as a room heat pump. Instead of creating all its heat directly from electricity, it collects heat from the air outside and moves it into your water. For the right home it can cut the energy used for hot water, and it works particularly well alongside solar.
2E Electrical can manage the electrical and plumbing work as one coordinated package, or work alongside your existing plumber.
Hot water is one of the bigger energy loads in a New Zealand home. EECA puts it at around 30% of the average household's energy use, so the system you choose has a real effect on your bills.
How much yours actually uses depends on the household, not just the cylinder. A couple with short showers and a modern cylinder uses a fraction of what a family of six with two teenagers and an old low-pressure tank will use.
The main things that drive hot water energy use:
Changing the hot water system can affect both your running costs and how the house feels day to day, especially when there is a big family or guests staying. The aim of this page is to help you weigh it up honestly before you spend anything.
Source: EECA homeowner guidance and heat pump water heater research. Actual performance varies by product, climate, installation and household use.
The key idea is that a hot water heat pump moves heat rather than producing all of it through a resistance element. That is why it can use less electricity for the same amount of hot water. EECA notes the coefficient of performance, or COP, for these units typically sits between 2 and 4 depending on the model and the conditions. A standard electric cylinder runs at a COP of about 1, meaning one unit of electricity in gives roughly one unit of heat out.
Outside air
Even cold Waikato air holds heat the unit can use.
Heat collected by the refrigerant
A fan pulls air across the evaporator coil.
Compressor raises the temperature
The refrigerant is compressed until it is hot enough to transfer.
Heat moves into the stored water
The condenser coil warms the water inside the cylinder.
Hot water ready to use
Available for showers, taps and appliances.
It is worth being clear about this. Most hot water heat pumps sold here are not compressor only. They keep an electric booster element in the cylinder for the times the compressor is not enough on its own.
The booster typically handles:
So when you see running cost figures for a hot water heat pump, that is usually a mix of compressor operation and some booster use, not the compressor doing all the work. We will always explain how a particular model is set up before you commit.
Source: EECA homeowner guidance and heat pump water heater research. Actual performance varies by product, climate, installation and household use.
There is no single best hot water system. The right one depends on your fuel, your budget, your space, and whether you have solar or plan to. Here is an honest side by side of the main options we get asked about across Hamilton and the Waikato.
The familiar option
Advantages
Limitations
Endless on demand
Advantages
Limitations
Where reticulated gas is not an option
Advantages
Limitations
Lower electricity use, strong solar fit
Advantages
Limitations
Smart control without a heat pump
Advantages
Limitations
We do not call any of these best without context. A cheap cylinder can be the right answer for a small low use household. A heat pump can be the right answer for a big family with solar. The comparison above is the starting point, not the decision.
This is where a hot water heat pump earns its keep for a lot of Waikato homes. Your hot water cylinder stores thermal energy. Instead of exporting all your excess solar during the day at a low rate, some of that energy can be used to heat and store water for showers and household use later.
Think of the cylinder as a thermal battery. You charge it with sunlight during the day, then draw on it in the evening when the panels are off but the family wants showers.
A typical solar aware day
Morning
The household uses the hot water stored from the day before.
Late morning to afternoon
Solar production rises. The hot water heat pump runs during the strongest solar window and the cylinder stores the heat.
Evening
The household uses the hot water produced during the day, without drawing as much from the grid.
How the heat pump is told to run during solar hours depends on your setup. The common options:
Whatever control method we use, it has to preserve reliable hot water, the required sanitisation cycles, booster availability, the manufacturer's requirements, and your comfort. We do not chase solar savings at the cost of cold showers.
We do not call solar electricity free. You pay for the panels and the hardware. What we can say is that surplus solar that might otherwise be exported at a lower rate can sometimes provide greater household value when used to heat water. That is the real opportunity, and it depends on your export rate, your retailer, and how much surplus you actually have.
Looking at solar as well? See what 2E Electrical covers for solar in Hamilton and the Waikato and we can plan the hot water and solar together so they actually work as one system.
Hot water heat pumps come in a few physical configurations. The right one depends on where the cylinder sits now, how much space you have, and whether you are starting fresh or working around an existing setup.
The heat pump and cylinder are combined into one outdoor unit.
The cylinder and the heat pump unit are separate.
A separate heat pump connects to a suitable existing cylinder.
Not every household needs a hot water heat pump.
Sizing a hot water system is not just about the number of bedrooms. A four bedroom home with two pensioners uses a very different amount of hot water to the same house with four teenagers.
We size based on what the household actually does, including:
Common capacity ranges
As a rough guide, smaller households often suit a cylinder in the 180 to 250 litre range. A typical family home often lands around 250 to 300 litres. Larger families, homes with baths, and high use or multi generational households usually need 300 litres or more. These are starting points, not rules.
We do not say a particular litre size suits every household of a given size, because it does not. The right way to size it is a proper assessment, looking at how you actually use hot water and what the electrical supply will allow.
A fair question. Hamilton and the surrounding Waikato get proper frosts and the foggy mornings hold the cold. The honest answer is that modern hot water heat pumps are designed to keep working through winter, but they behave differently when the air is cold.
In short, a hot water heat pump is not a summer only appliance. It will heat your water through a Waikato winter. It just does it more efficiently on a mild day than on a minus two morning, which is exactly why we size for the cold mornings and not the average.
Hot water heat pumps are not silent. They have a compressor and a fan, much like a room heat pump outdoor unit. Most people are not bothered by it once it is sited well, but placement makes a real difference. Here is what we consider:
We do not quote a universal noise figure here, because it varies by model and how it is installed. When we recommend a specific product we give you the manufacturer's noise data for that model, and we talk through where it will actually sit on your property.
The hot water heat pump market in New Zealand has grown quickly, and the brand and model line up changes often. Rather than publish a brand list that may be out of date next month, we choose the right product for the job in front of us.
What we assess for each product
When we recommend a specific model we give you the manufacturer's documentation for it, including the noise figure, warranty and electrical requirements. We only quote products we can genuinely supply and support, and we do not show installations we did not do.
A hot water heat pump sits across two trades. There is the electrical side, which we look after as registered electricians, and the plumbing side, which needs a qualified plumber. The thing that trips up a lot of installs is coordinating the two.
2E Electrical can coordinate the complete installation. That can include:
We can organise the plumbing as part of the package, so you deal with one coordinated team and one point of contact right through the job.
If you already have a plumber you trust, we are happy to work alongside them. We handle the electrical and solar side, your plumber handles the cylinder and pipework, and we make sure the two halves connect cleanly on the day.
Plumbing and gasfitting work is carried out by appropriately qualified and licensed tradespeople. We coordinate and organise that work, and we will be clear with you about who is doing what.
A lot of Waikato homes are moving away from gas, and hot water is often the first thing they look at. The decision is a bit bigger than just swapping the appliance, so here is what we work through.
Removing gas completely can create greater savings than replacing only the hot water appliance, but only when you weigh up all the remaining gas use and the disconnection costs. Sometimes the gas hob is worth keeping and only the hot water moves. We help you look at the whole picture.
Any gas work, including disconnection, must be carried out by an appropriately qualified and licensed gasfitter. We do not give gasfitting advice beyond our role in the job. We coordinate the right trade for that side of it.
If you already have an electric cylinder, a hot water heat pump is often a straight swap in principle, but the detail decides whether it is simple. Here is what we assess before we quote:
Some installations are a straightforward replacement and the old cylinder comes out and the new one goes in the same spot. Others need an electrical upgrade, a new circuit, or plumbing changes to suit the new system. We tell you which one yours is before any work starts.
Hot water is one of the things that should be designed early, not bolted on at the end. Getting it right during a build or a reno is cheaper and neater than retrofitting later, and it lets the hot water system work with the solar and the rest of the electrical design.
If you are building or renovating, we recommend thinking about:
Builders, architects and homeowners planning a renovation are welcome to get in touch early. We can advise on the hot water, electrical and solar design before the plans are locked, which is usually where the best savings and the neatest installs come from.
Talk to us about your build →Every household is different. A useful estimate needs to account for household size, actual hot water use, local climate, electricity and gas pricing, storage losses, the current system and the expected performance of the proposed hot water heat pump.
For an independent starting point, use EECA's Home Energy Savings Calculator. 2E Electrical can then assess your current bill, hot water system, solar generation and installation requirements to prepare a property-specific comparison.
Open EECA's Home Energy Savings CalculatorEECA's calculator is an independent government tool. We link to it for transparency and do not imply that EECA endorses 2E Electrical.
From the first phone call to the handover, here is how a hot water heat pump install with 2E typically runs.
We learn about the household, the current hot water system, and your future plans, including any solar.
We inspect the cylinder location, electrical supply, plumbing, drainage, airflow and solar potential.
We compare the suitable options and provide a clear written proposal with honest pros and cons.
We organise the required electrical and plumbing work, or coordinate with your existing plumber.
The old system is safely disconnected and the new system installed by the right trades.
The system is tested, programmed and checked for correct operation and safe temperatures.
We show you how to use the controls and adjust the schedule to suit your household.
We provide maintenance and support information, and can service the system going forward.
A hot water heat pump has both a refrigeration side and a cylinder side, so it has its own service requirements. The areas we typically look at:
We do not state a universal service interval, because it depends on the model, the installation location and how hard the system works. We follow the manufacturer's instructions and the conditions the unit is running in.
Hot water systems have their own service requirements that are different from room heat pumps. For room heat pump servicing, see our heat pump servicing page, and we will advise separately on hot water maintenance for your specific system.
A hot water heat pump is a strong option for a lot of Waikato homes, but it is not the right answer for every one. Here is an honest checklist to help you decide whether it is worth a proper assessment.
It may be a strong option if
Another option may suit better if
The right answer depends on the household, not just the appliance.
We are electricians first, so the electrical side of a hot water heat pump install is genuinely ours. The plumbing side we coordinate with the right trade. Here is what that looks like in practice.
We look at hot water, electrical supply, solar, tariffs and your future energy plans together, not in isolation.
The electrical work is assessed and completed under 2E Electrical by registered electricians.
We can organise a qualified plumber as part of the package, or work alongside your existing plumber.
We understand how to schedule hot water around solar generation and export rates so it actually saves.
We explain the advantages and limitations of each system rather than pushing the same product into every home.
We can assist with controls, electrical faults, servicing coordination and future system changes.
These are independent EECA resources on hot water heat pumps and a good place to start your own research. We link to them for transparency and do not imply that EECA endorses 2E Electrical.
Room heat pump supply, sizing and installation by registered electricians.
Learn moreAnnual servicing to keep your room heat pumps running efficiently.
Learn moreSolar PV design and installation that pairs with hot water heat pumps.
Learn moreWider electrical work across Hamilton and the Waikato.
Learn moreBook a hot water assessment or ask a question.
Learn moreWe can compare your current system, your hot water use, your electrical supply and your solar potential, then explain the options clearly. 2E Electrical can manage the electrical and plumbing work as one coordinated package, or work alongside your existing plumber.
Tell us about your home and hot water. We'll be in touch within 1 business day.