Rinnai Heat Pump Hot Water Review

Looking to cut hot water bills or move off gas? Rinnai’s heat pump hot water units sit in that practical middle ground: far cheaper to run than old resistive cylinders, simpler to retrofit than roof‑mounted solar hot water. In this rinnai heat pump review we focus on what matters day to day — efficiency, noise, sizing, installation and rebates — so you know where a Rinnai heat pump shines and where care is needed.

The quick verdict

Bottom line: A Rinnai heat pump is a safe, mainstream choice with national support. Expect strong bill savings versus an older electric tank, quieter operation than many air cons, and straightforward retrofits. The usual heat pump caveats apply: place it well, size it right, and plan for colder mornings.

• Pros
  • Much lower running costs than resistive electric; can pair well with daytime solar PV.
  • Reputable brand with national service coverage and readily available parts in Australia.
  • Qualifies for Federal STCs and state programs in many cases.
  • Easier to install than roof solar thermal; usually a like‑for‑like cylinder swap with outdoor unit.
• Cons
  • Higher upfront price than a basic electric tank.
  • Needs outdoor space and good airflow; performance dips in cold snaps.
  • Compressor/fan noise is audible; placement matters near bedrooms or neighbours.
  • Hot water recovery is slower than gas continuous flow; poor sizing can mean lukewarm showers at peak times.

Running costs and efficiency

Heat pumps move heat rather than make it, so they typically use 60–75% less electricity than old resistive tanks. In practical terms, that’s 2–4 times the heat per kWh depending on ambient temperature and the set water temperature. If you’re replacing an ageing 3.6 kW electric cylinder, you’ll usually notice a clear drop in your electricity bill once hot water is shifted to a heat pump.

Two factors make the biggest difference to bills:

• When it heats. If you have solar panels, schedule the system to run late morning to mid‑afternoon so it soaks up your own generation. On time‑of‑use tariffs, avoid the evening peak. See our guide to off‑peak hot water.
• What temperature you store at. By law, storage systems should be able to reach 60b0C to manage Legionella risk, but most homes mix down to 50b0C at taps via a tempering valve. Higher storage temperatures reduce efficiency a little but increase usable hot water volume.

Most heat pumps also qualify for Small‑scale Technology Certificates (STCs), which installers typically apply as an upfront discount. The exact number of STCs depends on the model and your postcode zone; ask your installer for the STC assignment paperwork.

Sizing: pick the right tank and recovery

Getting the size right matters more with heat pumps than with gas continuous flow. Undersize it and youb4ll hit lukewarm water after the dinner rush; oversize it and youb4ll pay a little more upfront and lose some efficiency keeping a bigger volume hot.

• 12 people: 13500 litres is common.
• 34 people: 20070 litres suits most families.
• 5+ people or high use (teenagers, large baths, rain showers): 27015 litres.

If youb4re moving from gas continuous flow to a heat pump, lean larger. Gas makes hot water on demand; a heat pump works best heating a stored volume once or twice a day, ideally during cheap/solar hours. Also consider:

• Peak timing: If everyone showers 6a0am, schedule a preheat before dawn or size up the tank.
• Baths: A single deep bath can use 8000 litres of mixed water; factor that into capacity.
• Incoming water temperature: Colder climates need a touch more capacity or a backup element to cover winter mornings.

Space, placement and noise

Like an outdoor air conditioner, a heat pump has a fan and compressor. Typical noise is in the ballpark of a quiet split system outdoors (often around 456 dB at 1 metre for many units), but placement is everything. Aim for:

• Clear airflow: Keep intake/exhaust sides unobstructed.
• Distance from bedrooms and neighbours: Around corners or down the side of the house is ideal.
• Solid base: A level concrete pad with anti‑vibration feet helps.
• Condensate drain: Ensure thereb4s a lawful discharge point; donb4t let it pool on paths.
• Coastal care: In salty or windy sites, ask about protective coatings and periodic fresh‑water rinses.

Installation and everyday ownership

Youb4ll need a licensed plumber, and usually an electrician, to connect power, fit a tempering valve (mandatory for bathrooms), pressure/temperature relief valves and earth bonding where required. Good installers will also:

• Insulate all hot pipes for several metres to reduce standby losses.
• Set schedules to match your tariff or solar production.
• Explain the controls so you can run a quick boost after heavy use.

Ownership is straightforward. Plan to:

• Test the PTR valve periodically as per the manual.
• Check the sacrificial anode on the storage tank every few years in hard or aggressive water; replace if needed to prolong tank life.
• Keep the coil/fins clear of leaves and dust; a gentle hose and soft brush now and then helps.
• Watch winter behaviour: In frosty regions, expect defrost cycles. If mornings feel cooler, bring a heating window into mid‑afternoon when ambient temperatures are higher.

If you have a recirculation loop (common in large houses for instant hot water at distant taps), note that constant loop losses can erode savings. Ask your plumber about timers or smart pumps to limit run time.

Rebates, compliance and warranty

Three programs commonly apply to heat pump hot water in Australia:

• Federal STCs under the Small‑scale Renewable Energy Scheme: usually assigned to the installer as an upfront discount. The STC count depends on product and location.
• NSW Energy Savings Scheme (ESS): certain heat pump upgrades may be eligible when replacing electric resistance systems. Eligibility and paperwork change; check the official scheme page.
• VIC Solar Homes hot water rebate: eligible Victorian households can apply for a rebate for approved hot water heat pumps. Check the official Solar Homes site for current criteria.

Always get compliance certificates from your licensed trades. For warranty, Rinnai typically provides multi‑year coverage split across tank, parts and labour, but terms change — get the current warranty document with your quote and confirm who handles service in your area.

Alternatives to consider

If you have great sun and roof space, solar thermal hot water with electric boost can beat most heat pumps on winter performance, though installs are more complex. In small homes or where outdoor placement is tricky, a modern high‑efficiency electric storage unit on a controlled tariff can be a low‑cost stop‑gap. If youb4re on bottled LPG, moving to a heat pump usually wins hands‑down on running costs. For households wedded to long, back‑to‑back showers, gas continuous flow still excels on recovery but wonb4t decarbonise your hot water.

Overall, this Rinnai heat pump review finds the technology a strong fit for most detached Australian homes, especially those with solar PV. Prioritise smart scheduling, thoughtful placement and the right tank size, and youb4ll get quiet, reliable hot water at a fraction of the running cost of an old electric cylinder.