Hot water systems: which option is best for Wellington homes?

Choosing the right hot water system for a Wellington home means balancing energy use, running costs and carbon emissions — while taking into account local constraints such as house type, available services (natural gas vs LPG vs all-electric), space and Wellington’s temperate, windy climate. This guide compares the main options and highlights what matters for suburbs across the Wellington region (Karori, Khandallah, Johnsonville, Newtown, Mount Victoria, Miramar, Island Bay, Lower Hutt, Upper Hutt, Porirua and others).

Overview of common systems

Electric storage cylinders (resistance) – traditional electric hot water cylinders with an immersion element.
Electric instantaneous (on-demand) – small electric water heaters that heat as water flows.
Heat pump hot water systems – extract heat from ambient air to heat water (typically much more efficient than resistance).
Gas hot water – continuous flow or storage systems that use natural gas or LPG (where reticulated gas is available).
Solar hot water – solar thermal collectors with a backup system (electric or gas) or solar PV paired with electric/heat pump systems.

Energy use — which is most efficient?

On pure energy efficiency:

Heat pump hot water is typically the most energy-efficient electric option because it moves heat rather than generating it directly. In many NZ conditions it can deliver two to four times the hot water per unit of electricity compared to electric resistance.
Solar thermal can cut energy use dramatically in summer and significantly through the year if sized and oriented well, but it usually needs a backup on cloudy periods.
Gas continuous flow can be efficient for some household patterns (no storage losses) but depends on availability and the efficiency of the unit.
Electric resistance (storage) is the least efficient — it wastes heat through standby losses and uses the most energy for the same hot water delivered.

Running costs — what will you pay?

Running costs depend on the system efficiency, local energy prices and household usage. General patterns:

Heat pump — usually offers the lowest electricity bills for hot water (often the best payback vs electric resistance). Noise, location of the outdoor unit and upfront cost are factors to consider, especially in tight inner-city sections in Wellington (e.g., Mount Victoria, Newtown) where neighbours are close by.
Solar + backup — can produce the lowest ongoing fuel bills if panels/collectors are well-installed and household hot-water demand aligns with solar output. In Wellington’s cloudier months, the backup system (electric or gas) will still run.
Gas — where natural gas is available (some parts of the Wellington region and Lower Hutt/Porirua suburbs have reticulated gas, others do not), gas can be cost-effective for continuous flow systems. LPG is more expensive than reticulated natural gas.
Electric storage — lowest installation cost but highest running cost due to low efficiency and heat loss from cylinders.

Carbon emissions — what’s greener in Wellington?

New Zealand’s grid is predominantly renewable, which changes the carbon picture compared with many countries. That means:

Electric heat pumps generally have low carbon emissions because they use relatively little electricity and the NZ grid has a high renewable share.
Solar thermal and solar PV deliver the lowest lifetime emissions when they displace grid energy.
Gas (natural gas or LPG) emits direct CO2 and methane risk, so it will usually have higher carbon than an efficient heat pump on a mostly renewable grid.
Electric resistance produces higher emissions per litre of hot water than a heat pump in NZ because it uses more electricity for the same output.

Wellington-specific considerations

Climate — Wellington’s temperate maritime climate is well-suited to heat-pump hot water systems. Mild winters mean heat pumps retain good efficiency year-round compared with colder regions.
Property type — inner-city and hillside properties (Mount Victoria, Oriental Bay, Newtown) may have limited space for an outdoor heat-pump unit or solar collectors; apartment buildings may need a communal system or rooftop access for solar collectors.
Noise and neighbours — heat pump compressors create some noise. In denser suburbs (Newtown, Mount Victoria, Island Bay), check siting and local council rules on noise and placement.
Gas availability — not all Wellington suburbs are on the reticulated gas network. Confirm whether natural gas is available in your street before considering gas options.
Solar potential — Wellington is windier and cloudier than the sunniest parts of NZ, but solar thermal or PV still contributes significantly to hot-water needs, especially on sunny spells.

Upfront cost vs lifetime cost

Typical trade-offs:

Lowest upfront cost: electric storage cylinder (replacement is straightforward and cheap).
Moderate upfront cost: gas continuous flow (if gas is available); also electric instantaneous units.
Higher upfront cost, lower lifetime cost: heat pump hot water; solar thermal or solar PV + heat pump combinations — these require bigger initial investment but often lower bills and lower carbon emissions over the life of the system.

Compliance and installation in New Zealand

All hot water work should be completed by a licensed and experienced plumber and, where gas is involved, a certified gasfitter. Installations must meet the New Zealand Building Code and applicable standards and local council requirements. A reputable installer will advise whether a building consent is required (often not required for like-for-like cylinder swaps but may be for changes to flues, gas lines, or structural modifications) and will provide documentation and safety checks.

Which system is best for your Wellington home?

Short guidance by typical scenario:

Inner-city terrace/apartment (limited outdoor space) — electric instantaneous or compact electric storage may be simplest; consider a heat-pump system only if you can site the outdoor unit away from neighbours.
Detached family house with outdoor space — a heat pump hot water system often gives the best balance of low running cost and low carbon. Combine with insulation upgrades and low-flow fixtures for extra savings.
House with good solar access — solar thermal or solar PV paired with heat pump or efficient electric backup can deliver the lowest lifetime carbon and bills.
Where reticulated gas is available and preferred — gas continuous-flow systems can be effective, especially for high-demand households, but have higher carbon impacts than electric heat pumps on NZ’s largely renewable grid.

Practical tips before you switch

Get a household hot-water audit — how many occupants, typical showers and hot-water uses. That will guide system sizing.
Insulate cylinders and pipework to reduce losses and improve comfort.
Check for available services (natural gas, reticulated gas) at your address in Wellington or nearby suburbs like Lower Hutt and Porirua.
Ask about warranties, service requirements and the expected life of the system.
In multi-unit buildings, coordinate with body corporate or landlords on system changes.

Local help and next steps

If you’re in the Wellington region and want a local assessment, installers like Accrete Plumbing can provide site visits, system comparisons (energy, cost and carbon) and full installation by licensed tradespeople. For more information about services and to request an on-site quote, visit Accrete Plumbing at https://www.accreteplumbing.co.nz/.

Choosing the right hot water system for a Wellington home is a balance of upfront cost, running cost, carbon impact and practical site constraints. For most Wellington households seeking low emissions and lower bills, a heat-pump system — or a solar-plus-heat-pump combination — is an excellent place to start the conversation.

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