Choose a replacement hot water system by matching the household’s busiest period of use, the available installation space and the home’s future energy plan. The old system’s fuel and tank size are useful background, but they should not automatically determine the replacement. A renovation may change bathrooms, occupancy and electricity demand at the same time.
For many Australian households, an appropriately selected heat pump deserves a close look because it can use less electricity than conventional electric resistance heating. Solar thermal, gas and electric storage systems still need to be compared against the actual property constraints. The useful comparison is a complete installed system delivering the required hot water, with transparent operating assumptions.
Describe demand before choosing equipment
Record how many people normally use the home and when they shower. Include regular guests, bath use and whether several bathrooms operate together. A household with staggered showers has a different demand pattern from one where everyone gets ready within the same short period.
Tell the installer about the renovation’s intended changes. Adding a second bathroom does not necessarily double daily hot water use, but it can increase simultaneous demand. A large bath can create a concentrated draw that a simple occupant count fails to capture.
Check whether the washing machine and dishwasher use a hot water connection or heat their own water. Provide actual appliance information instead of assuming that every appliance draws from the household heater. This helps the installer size for the real system.
Separate stored capacity from recovery
A storage tank’s nominal volume is only part of its usefulness. Recovery rate, operating schedule, local conditions and the temperature of incoming water affect how it serves the household. Ask the installer to explain the proposed model using your busiest ordinary day.
Include an occasional demanding day
Discuss a realistic guest visit or a day with several baths and showers. Decide whether the household wants capacity for that occasional peak or is comfortable spacing use. The answer is a lifestyle choice that should be explicit before the equipment is ordered.
Heat pump hot water: assess the site as well as efficiency
A heat pump uses electricity to move heat from the surrounding environment into water. Your Home explains that this can use substantially less energy than heating water directly with an electric element. Its actual performance depends on the product and operating conditions.
Ask the installer to assess climate suitability, outdoor placement, airflow, condensate management and service access. A narrow side passage may appear convenient on a plan but need careful assessment once fences, bedroom windows and neighbouring uses are considered.
Noise deserves attention before installation. Request the manufacturer’s information and discuss the proposed operating times. A model placed outside a bedroom should be considered differently from one beside a utility area, even if both positions fit the tank footprint.
Check how the system responds to high demand or colder conditions, including any boosting function. Avoid comparing efficiency figures quoted under different test conditions as though they predict the same household result.
Solar hot water: make the roof part of the decision
Solar thermal hot water collects heat at the roof and transfers it into the water-heating system. It differs from rooftop solar photovoltaic panels, which generate electricity. The distinction matters when deciding how to use limited roof space.
Ask the installer to assess shading, roof condition, collector placement, tank arrangement and the appropriate booster. A roof-mounted tank has different structural and visual implications from a system with a tank at ground level.
Energy.gov.au notes that solar hot water systems can need gas or electric boosting when solar input is insufficient. Include that energy use in the operating comparison rather than treating every litre of hot water as free.
If roofing work is already planned, coordinate the sequence using the guide to solar equipment and roof renovations. Removing and refitting equipment soon after installation can undermine an otherwise sensible purchase.
Gas hot water: examine the whole gas connection
Gas options include storage and continuous-flow arrangements. The latter heats water as it is used, so its ability to serve simultaneous outlets depends on the selected equipment and available supply. A gas connection already serving a cooktop does not by itself establish capacity for a new water heater.
Have a licensed gasfitter assess the proposed model, pipework, location and ventilation or flue requirements. Local restrictions and the property’s circumstances must be checked before assuming a gas replacement or new connection is available.
Consider the household’s longer-term direction. If hot water would be the only remaining gas appliance, the comparison should include the ongoing gas supply charges that could potentially be avoided by leaving gas altogether. Confirm disconnection arrangements and costs with the relevant providers.
Do not retain gas solely because the old appliance used it, or remove it solely because an advertisement promises a universal saving. Compare a documented installation and operating scenario for the home.
Conventional electric storage: simple equipment, broader cost questions
Electric resistance storage heats water directly in a tank. It can be a practical replacement where the installation is straightforward, but energy consumption and tariff arrangements need close attention. A low initial quotation can become a more expensive choice over years of use.
Ask whether the proposed tank and household demand suit any controlled-load or time-based arrangement available at the property. The tariff, wiring and operating schedule must work together. A cheap heating window is useful only if sufficient hot water remains available when needed.
Rooftop solar electricity can change the operating calculation, but using that electricity for water heating may reduce exports or compete with other household uses. Treat it as a resource with alternatives, rather than assuming it has no value.
Compare installation constraints on one page
Prepare a short site schedule for the installer. It should include the current heater location, access route, available outdoor area, switchboard position, roof work and the proposed bathroom layout. Photographs can identify obvious constraints before a site visit.
- Confirm how the old unit will be removed and disposed of.
- Identify the proposed tank, outdoor unit or collector position.
- Include plumbing, electrical and gas work where applicable.
- Ask how relief discharge, drainage and service access will be handled.
- Record any approvals, inspections or property permissions that apply.
A different fuel or technology can require work beyond the appliance connection. If electricity demand is changing across the house, coordinate the assessment with the switchboard upgrade plan before signing separate trade contracts.
Keep the hot water route sensible
Moving a heater can improve service access or free valuable space, but it also changes pipe routes. Ask the plumber to explain the effect on waiting time at distant fixtures and on the amount of water left cooling in the pipework.
During bathroom planning, compare the heater location with the most frequently used outlets. A visually tidy location at the far end of the property may be less convenient every morning.
If a circulation arrangement is proposed, request a separate explanation of its controls, energy use and maintenance. It should address a defined problem rather than be added automatically to compensate for an unnecessarily long layout.
Compare complete installed budgets in AUD
Use itemised quotations rather than advertised starting prices. The quotation should show equipment, labour, removal, supporting works and any discount separately. This makes it easier to understand whether two installers have allowed for the same property conditions.
As an illustrative comparison only, one replacement scenario might allow AUD $1,500 including GST for equipment, AUD $650 for plumbing and AUD $250 for disposal and minor associated work, totalling AUD $2,400. A different technology scenario might allow AUD $3,300 for equipment, AUD $900 for plumbing, AUD $550 for electrical work and AUD $250 for disposal, totalling AUD $5,000 including GST.
These invented figures demonstrate scope comparison; they are not current market prices or standard prices for particular technologies. Major roof work, switchboard replacement and long pipe relocation are excluded. Actual quotations may include different items entirely.
The renovation quote comparison guide helps identify assumptions. Ask for a clear price before incentives and a separate net price based on verified eligibility.
Calculate running costs with visible assumptions
Compare expected purchased energy, the applicable tariff and any additional fixed charges. Use the same household demand assumption for every option. A comparison that assumes shorter showers for only one system is measuring behaviour as well as technology.
For an illustrative electricity example, assumed annual consumption of 900 kWh at AUD $0.30 per kWh including GST costs AUD $270. At 2,600 kWh on the same assumed tariff, the cost is AUD $780. The difference is AUD $510 a year before maintenance, tariff changes or solar allocation.
If the more efficient scenario costs an additional AUD $2,600 to install, dividing that amount by the illustrative AUD $510 difference gives about 5.1 years. This is a simple scenario calculation, not a promised payback or a forecast for a specific heater.
Ask the installer to provide product-based assumptions for your climate and use pattern. Include a less favourable scenario so the decision remains understandable if electricity prices, household size or operating hours change.
Verify incentives without letting them choose the system
Government support and certificate arrangements can change, and eligibility can depend on the property, equipment, installer and existing system. Confirm the current terms before signing, including who receives or assigns any certificate benefit.
Your Home notes that advertised installed prices can already include incentive discounts. Ask for those amounts to be shown explicitly so a discount is not counted twice in the household budget.
A rebate can improve affordability, but it does not resolve poor placement, insufficient capacity or weak local service support. Compare the net price only after the proposed installation meets the household’s practical requirements.
Protect safe temperatures and commissioning settings
Storage, delivery temperature and tempering arrangements must be set by the appropriately qualified installer for the system and applicable requirements. Do not lower safety-related settings based on a generic energy-saving tip or a neighbour’s experience.
Ask the installer to explain the controls the household may use, such as approved schedules or holiday settings, and which settings should remain under professional control. Keep the operating instructions with the commissioning information.
For homes with children, older occupants or changing accessibility needs, explain those circumstances during design. The goal is a suitable hot water service at the fixtures as well as an efficient appliance outside.
Plan for installation day and an unexpected failure
Agree when water and energy supplies will be interrupted, how the household will manage and when the new system is expected to deliver hot water. Include access for a bulky tank and protection of finished paths or floors.
If the old unit has failed, ask whether a temporary professionally installed arrangement is available while a suitable replacement is selected. Energy.gov.au identifies temporary equipment as an option some installers provide; availability and cost need local confirmation.
Add the replacement to the renovation timeline so associated trades attend in the right order. Avoid booking the final plumbing connection before the necessary electrical or structural work is ready.
Revisit the schedule after the household settles in
Once the renovated home is occupied, keep a short record of any occasions when hot water is insufficient or heating occurs at an inconvenient time. Note the number of showers, unusual guest demand and relevant control settings. That gives the installer useful information if an adjustment is needed.
Avoid changing several settings at once. Ask the installer which permitted operating change addresses the observed problem and whether it affects energy use. A clear record helps distinguish a capacity issue from a schedule that no longer matches the household.
If solar electricity, a battery or a different tariff is added later, review the water-heating schedule again. The original arrangement may still work, but the most useful timing can change as the home’s other energy demands evolve.
Check service support before the final choice
Ask who services the equipment locally, what routine maintenance is specified and how warranty responsibilities are divided between the product and installation. A long headline warranty may cover different components for different periods.
Check water-quality suitability with the manufacturer and installer, especially where local supply characteristics need special consideration. Keep proof of purchase, model details and required maintenance records in one place.
Include realistic maintenance allowances in the household renovation budget. A useful hot water replacement balances comfort, installed cost, future energy use and the ability to keep it working without unnecessary disruption.