Homeowners · For new Zealand homeowners choosing a water heating energy source
Gas or electric hot water: which suits your home?
Choose gas or electric hot water by comparing your existing connections, household demand, installation constraints and ongoing energy arrangements. Electricity includes both conventional cylinder heating and heat pump options, so it is not a single technology. Gas may suit an existing installation, but a new connection needs to be assessed as part of the whole project rather than assumed to be worthwhile.
Checked against official sources on by Stately Plumbing.
The short answer
- Separate the energy source decision from the choice between stored and continuous flow hot water.
- Include heat pump water heating when comparing electric options.
- Compare installed scope, current energy plans, maintenance and household suitability rather than appliance labels.
Untangle fuel choice from system design
Gas versus electricity describes the energy source, while cylinder versus continuous flow describes how hot water is provided. BRANZ notes that both storage and continuous flow systems can use different energy sources. A conventional electric cylinder, a heat pump water heater and a gas continuous flow unit therefore involve different combinations of technology and delivery. Start with those distinctions so the comparison does not accidentally set a fuel against a storage method.
When discussing gas hot water, ask the contractor to name the proposed system and explain why it suits the property. Do the same for the electric alternative. A useful comparison considers where equipment will sit, how water reaches the outlets and how the system handles the household's busiest period. Fuel preference alone cannot establish whether the finished installation will provide the shower performance or convenience you want.
Use a comparison that includes heat pumps
The table is a starting point for questions, not a ranking of products. BRANZ identifies energy source, capacity, layout and recovery as design decisions and describes heat pump water heating as an option for homes seeking lower operational carbon. Product suitability still depends on the property. Ask the installer to explain the practical implications of each option rather than treating an appealing feature as proof that a complete system is suitable.
A fair shortlist should distinguish keeping a serviceable arrangement from replacing it with a different technology. An existing gas connection may make a gas proposal less involved than adding gas to an electric home. Equally, retaining electricity does not mean you must select another conventional cylinder. Compare the work required from your actual starting point, including any redundant equipment and connections that would need attention after a change.
| Consideration | Conventional electric cylinder | Heat pump water heating | Gas hot water |
|---|---|---|---|
| Main design question | Does storage and recovery suit household demand? | Does the equipment and storage arrangement suit the site? | Does the proposed storage or flow arrangement suit demand? |
| Existing services | Assess electrical supply and controls | Assess electrical supply, siting and connections | Assess available gas supply and pipework |
| Space | Allow for the selected cylinder and service access | Allow for the selected equipment layout and service access | Check appliance location and applicable installation constraints |
| Ongoing comparison | Use the actual electricity plan and household use | Include performance assumptions and maintenance | Include the actual gas plan or LPG arrangement and maintenance |
| Changeover scope | Identify any pressure or capacity changes | Identify equipment, plumbing and electrical changes | Identify supply, gasfitting, plumbing and certification |
Describe the household's busiest demand
Tell the installer how hot water is used, not simply how many people live in the home. Overlapping showers, a frequently filled bath and changing work schedules can influence the design differently. Mention planned bathrooms or a likely change in occupancy. The goal is to match capacity and delivery to real use without choosing a larger or more complicated installation just because it sounds more capable on paper.
For electric hot water cylinders, ask how storage and recovery would accommodate that demand. For a gas continuous flow proposal, ask how simultaneous outlets and seasonal inlet water conditions affect the selected unit's delivery. Neither label guarantees comfort. Request an explanation based on the proposed equipment and your fixtures, and separate a water heating limitation from a pressure or pipework problem that a fuel change alone would not resolve.
Compare energy arrangements without invented savings
Running cost comparisons need current information about your household and the plans available to it. Ask which energy rates, fixed charges and usage assumptions support a proposal. For LPG, include the relevant supply arrangement rather than borrowing a natural gas example. If changing water heating would remove your last use of gas, ask the supplier what that means for continuing charges and any account or connection arrangements.
Treat a claimed payback as a calculation to inspect, not a promise. Ask whether it includes installation, maintenance and any additional work needed at your property. A heat pump option should be compared on its own stated assumptions rather than grouped with conventional electric resistance heating. Avoid transferring another household's bill to yours, particularly if shower habits, occupancy or the amount of hot water used differ substantially.
Check location and distribution before choosing
Equipment location affects more than the space it occupies. BRANZ recommends minimising hot water pipe runs to reduce waste and improve efficiency. Moving the heating source far from frequently used outlets can undermine an otherwise attractive proposal. Ask the contractor to explain the likely pipe routes and how the planned location relates to the kitchen, bathrooms and laundry, especially if the change is intended to free an indoor cupboard.
A heat pump proposal needs a practical siting discussion for the particular product, including service access and any effects relevant to neighbouring spaces. A gas proposal needs an assessment of its appliance location and installation requirements. Do not select a location solely from a sales photograph. Ask for the site assumptions to be written down, along with any building work, electrical work or surface restoration excluded from the installation price.
When to call a licensed gasfitter to assess fuel options
Changing the energy source does not remove the need to manage hot water delivery safely. MBIE states that the 50°C maximum applies to new personal hygiene fixtures in most buildings installed on or after 2 November 2024 when using the G12/AS1 compliance pathway. It is not a retrospective requirement for every existing fixture. Ask how the actual installation will manage delivery temperatures rather than adjusting controls yourself to make a comparison.
Use a licensed plumber for the plumbing scope and appropriately licensed gasfitting expertise for gas work. WorkSafe says connected gas work requires a Gas Safety Certificate, with Certificates of Compliance supporting general and high risk gasfitting. Ask who will provide the applicable records and include them in the handover. The gas certification guide explains these documents in more detail and helps distinguish them from ordinary appliance paperwork.
Choose against clear household priorities
Write down what you want the change to achieve before deciding. Restoring a failed system, increasing available hot water, releasing cupboard space and reducing operational carbon are different priorities. BRANZ recommends considering operational carbon alongside system design and identifies heat pump water heating as a useful option in a lower carbon home. That supports including heat pumps in the shortlist, not claiming that any particular product is right without assessment.
Request written options that show equipment, included trades, removal, controls, testing and exclusions. Ask the contractor to explain what each option improves and what it leaves unchanged. If a working system already meets your needs, include repair or planned replacement in the discussion rather than assuming immediate conversion is necessary. A sound choice follows the household's priorities and the property's constraints, with commercial and performance assumptions visible before approval.
Common questions
Is gas always cheaper to run than electric hot water?
No universal answer fits every household. Compare current energy plans, fixed charges, equipment performance and actual use. Keep conventional electric cylinders separate from heat pump water heating because they are different technologies.
Does choosing electricity mean keeping a standard cylinder?
No. Electric options include conventional cylinder heating and heat pump water heating. Ask which technologies suit the site and request separate proposals so their equipment, installation requirements and operating assumptions can be compared.
Is an existing gas connection a reason to stay with gas?
It is relevant, but not decisive. Compare the condition of existing equipment, the proposed installation, ongoing supply arrangements and your priorities. An established connection does not prove that replacing gas equipment is the best option.
Will changing fuels fix weak shower pressure?
Not necessarily. Ask a licensed plumber to assess the pressure arrangement, pipework, controls and fixtures. A fuel change may leave those limitations untouched unless the proposal specifically includes the work needed to address them.
When should I involve a licensed gasfitter?
Involve an appropriately licensed gasfitter when assessing installation, alteration or removal of gas equipment or pipework. Ask about the applicable certification before approving the project, rather than treating gas connections as a minor plumbing detail.
Sources
We checked this guide against these official pages. Rules change, so confirm anything that affects a decision with the source.
Need a hand with this?
Stately Plumbing is Kiwi-owned and has worked across Auckland since 2012. Phone us or send the details and we will tell you what we see and give a clear quote before work starts.