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A solar hot water system installed by RCM on a Sunshine Coast roof

Compare Hot Water Systems on the Sunshine Coast

Five system types, compared on the things that actually decide which one suits a property. No winner declared, because there is not one.

Call 0415 611 356Request a quote

Most hot water comparisons start from the answer and work backwards. This one does not, because the honest position is that the right system depends on what your property already has: the connections available, the space outside, the roof, how many people live there and how they use hot water.

What follows is the set of factors we weigh when someone asks us to recommend a replacement for a Sunshine Coast property. Read down the column that matches what you are considering, or read across a row if one particular constraint is the one that worries you.

A Rheem Ambiheat heat pump hot water system, manufacturer product image

Hot water systems compared

Hot water systems compared
FactorHeat pumpSolarElectric storageGasContinuous flow
Upfront costHigher than electric storage. Unit cost plus positioning and condensate drainage.Highest of the five in most cases. Collectors, tank, pump, controller and roof work.Lowest to buy and install, which is why it is common as an emergency like-for-like swap.Mid range for the unit. Cost moves a lot with whether gas is already connected.Mid range. Wall-mounted unit, but may need gas or electrical capacity upgrades.
Ongoing energyUses substantially less electricity than conventional electric storage. The actual figure depends on model, climate, installation and use.Depends heavily on how much work the booster does, which depends on roof orientation, tilt and shading.Generally the most expensive to run of the electric options. Controlled-load tariffs change the picture.Depends on fuel. Mains natural gas and bottled LPG behave very differently on cost.Depends on usage. No standby loss from a stored tank, but heats on demand at full rate.
Household sizeTank sizing as for storage. Recovery rate matters for larger households.Tank sizing as for storage, plus enough collector area for the demand.Sized by tank capacity and recovery. Undersizing shows up as running out.Storage sized by tank; continuous flow sized by flow rate instead.Sized by flow rate, not capacity. The question is how many outlets run at once.
Space requiredOutdoor unit plus tank, with real clearance for airflow. Often the deciding factor.Roof area for collectors plus a tank, either on the roof or at ground level.Tank only. Can go indoors in a cupboard or outdoors against a wall.Tank for storage, or a compact wall unit for continuous flow.Smallest footprint. Wall-mounted unit, no tank.
NoiseHas a fan and a compressor. Position away from bedrooms and boundaries.Generally quiet. Any noise is usually the circulation pump.Effectively silent in normal operation.Burner noise while heating, usually modest.Burner and fan noise while running, only while hot water is being drawn.
Roof suitabilityNot required. The unit sits at ground level.Critical. Orientation, tilt, shading and roof condition all matter.Not required.Not required.Not required.
Works with solar powerStrong pairing. Many models can be scheduled to heat while solar PV is generating.A separate technology entirely. Solar thermal heats water directly rather than making electricity.Can be scheduled to daytime, though it uses far more electricity to do the same job.Limited relevance, since it burns gas rather than using electricity.Depends which fuel the unit uses.
Existing connection neededElectrical supply, and somewhere for condensate to drain.Electrical or gas supply for the booster.Electrical supply. Often already there in a like-for-like swap.Gas supply with adequate capacity, mains or bottled.Gas or electrical supply, with enough capacity for the unit's peak draw.
IncentivesEligible air-source models can create STCs. Model eligibility must be checked against the current register.Eligible solar water heater models can create STCs, on the same conditions.Does not attract the same STC treatment.Not applicable.Depends on the technology in the specific unit.
Main limitationPosition and noise. If there is nowhere sensible to put it, it is the wrong choice.Roof and shading. A poor roof means the booster carries the load and the economics change.Running cost, and it will run out if undersized.Fuel availability and emissions. Gas burns fuel and gas storage loses heat from the tank.Flow capacity. Too many outlets at once and the temperature drops.

Narrow it down

Eight questions about the property. It will not tell you which system to buy, because the things that settle that are where the old unit sits, what your switchboard carries and which way the roof faces. What it will do is show you which options are worth talking about and which are probably not, and why.

  1. 01 How many people live at the property?
  2. 02 How many bathrooms?
  3. 03 Are baths or spa baths used?
  4. 04 Is solar PV installed?
  5. 05 Is natural gas available at the property?
  6. 06 Is the replacement urgent?
  7. 07 Is there suitable outdoor space for a unit?
  8. 08 Is roof shading significant?

0 of 8 answered.

Why we will not tell you one system is best

Every one of these systems is the right answer somewhere and the wrong answer somewhere else. A heat pump in a townhouse with no sensible outdoor position is a bad recommendation regardless of how efficient it is. Solar on a south-facing, shaded roof will disappoint. Electric storage in a household that keeps running out is a problem you have already met.

A recommendation that ignores your property is a sales pitch. What actually matters is the order in which the constraints bite: what is connected, what space exists, how much hot water the household needs at once, and how urgent the replacement is. Once those are on the table the field usually narrows to one or two options on its own.

Where the savings claims come from, and why we do not repeat them

You will find large savings percentages attached to heat pumps and solar hot water, often without any statement of what they assume. Australian Government guidance is clear that heat pumps can use considerably less energy than conventional electric storage, but equally clear that real performance depends on the model, the climate, the installation, the settings and how the household uses hot water.

The same applies to solar. Collector orientation, tilt and shading materially change the outcome, so the same system on two roofs in the same suburb can produce quite different results.

That is why this page carries no figures. A number without its assumptions is not information, and the sources below are better read directly than summarised by a plumber's website.

What about incentives

Small-scale Technology Certificates are a federal scheme, and they are the mechanism behind most of what gets advertised as a hot water rebate. Only eligible solar water heater and air-source heat pump models can create them, and eligibility is model-specific and checked against the current official register rather than assumed.

There are also administrative conditions, including the period within which certificates must be created. Any quote that includes a certificate benefit should be clear about whether it has been assigned to the supplier and already discounted, or whether you are claiming it separately.

Because these schemes change, treat any figure you read anywhere, including here, as needing a current check rather than as settled.

How we would approach it at your place

Start with what is already connected, because that decides more than anything else. Then look at where a system can physically go, which rules options in or out faster than cost does. Then size it against how the household actually uses hot water, not against the size of the house.

Then, and only then, is it worth talking about running costs, because by that point there are usually only one or two realistic options and the comparison is concrete rather than theoretical.

If you want that conversation about your property, call 0415 611 356 or send photos of what you have now.

Sources

Frequently asked questions

Which hot water system is cheapest to run?

It depends on what you are comparing and on your tariff. A heat pump generally uses much less electricity than conventional electric storage to deliver the same hot water, and solar shifts some of the load to the sun. But bottled LPG behaves differently from mains gas, and a controlled-load electric tariff changes the arithmetic again. Running cost is genuinely property-specific.

Should I just replace like for like?

Often it is the right call, particularly when the system has failed and you need hot water back today. It is the fastest and usually the cheapest option because the connections are already there. It is worth pausing only if the old system was undersized, if you have solar power, or if the position was always awkward, since a failure is the natural moment to fix those.

Does a bigger tank mean I stop running out?

Sometimes, but not always. If you run out because the tank is genuinely too small for the household, more capacity helps. If you run out because an element or thermostat has failed, or because there is a leak on the hot line, a bigger tank just gives you a larger version of the same problem. Worth diagnosing before upsizing.

How do I compare two quotes for different systems?

Compare what is included rather than the headline number. Check removal and disposal of the old unit, any electrical or gas work, valves and fittings, commissioning, and whether a certificate benefit has already been discounted or is yours to claim. A quote that is much cheaper usually differs in what it leaves out rather than in the price of the unit.

Can I see how a system performs before committing?

Not directly, which is why the assumptions matter so much. What you can do is check the model against the manufacturer's published specifications and, for heat pumps and solar, against the official register that governs certificate eligibility. Ask for the exact model number on the quote so you can look it up rather than relying on a category name.

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Related services

Want this narrowed down for your property?

Send a photo of what you have now and tell us how many people it serves.

Call 0415 611 356Request a quote

RCM works across Sunshine Coast and the hinterland. See the full Sunshine Coast service area for where we work regularly and where we travel on different terms.

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