Yes, but the answer depends on which system you choose. Modern heat pump hot water systems handle Highlands winters well, including the frosts that are a regular part of life in Bowral, Moss Vale, and Mittagong. Winters here are genuinely cold. July averages a maximum of 12°C and a minimum of around 2°C. Sub-zero overnight frosts occur regularly. That changes what a heat pump hot water system needs to do, and which models are actually suited to the job.
Below we cover how performance holds up in cold conditions, what separates a suitable system from one that will struggle, and which brands we recommend for Highlands homes.
How a Heat Pump Hot Water System Works
A heat pump hot water system moves heat from the surrounding air into your water storage tank, it does not generate heat directly. Because it transfers heat rather than creates it, the system uses far less electricity than a conventional electric storage unit.
Efficiency is measured by COP (Coefficient of Performance). A COP of 3.5 means the system produces 3.5 units of heat for every one unit of electricity consumed. A standard electric element has a COP of 1.0. That gap is what drives the running cost savings, and understanding it also explains why cold weather matters.
How Cold Weather Affects Heat Pump Performance
When ambient temperature drops, there is less heat energy in the air to extract, so the system works harder. That COP of 3 to 4 in summer can fall to around 2 to 2.5 on cold winter mornings, but even at COP 2, you are still using roughly half the electricity of a conventional electric system. The real problem is not reduced COP. It is choosing a system not rated for low ambient temperatures.
Standard Models vs Cold-Climate Models
Standard heat pump hot water systems use R290 (propane) refrigerant and are rated to around 5°C. Cold-climate models use CO₂ (R744) refrigerant and maintain full heat pump efficiency down to -10°C to -25°C. For the Southern Highlands, a CO₂ unit is the right starting point, not a standard model that works in Sydney’s winter but struggles here.
| Feature | Standard Model (R290) | Cold-Climate Model (CO₂) |
|---|---|---|
| Rated operating range | Down to ~5°C | Down to -10°C to -25°C |
| COP at low temps (2-5°C) | Drops sharply; may switch to boost element | Maintains heat pump efficiency |
| Boost element use in Highlands winters | Frequent | Minimal to none |
| Running cost in winter | Climbs significantly | Stays low year-round |
| Best suited to | Coastal and warmer climates | Southern Highlands and similar regions |
What to Look for When Choosing a System for the Highlands
The Highlands climate sits firmly in the cold-climate zone. When we assess a hot water system for a local home, these are the factors that determine whether it will perform well through winter:
• Refrigerant type: CO₂ (R744) units hold their efficiency below 0°C. R290 units are built for warmer conditions and will lean on their boost element when frosts hit.
• Minimum operating temperature: look for a unit rated to at least -10°C to ensure it stays in heat pump mode on the coldest Highlands nights.
• Boost element reliance: a well-specified cold-climate unit should rarely need its boost element. If it is triggering frequently, running costs rise to match a conventional electric system.
• Tank capacity: a larger tank allows the system to heat water during the warmest part of the day and store it, reducing how often it runs in cold overnight conditions.
• Installation position: north-facing walls with good airflow give the unit access to more ambient warmth. Enclosed, shaded spots make cold-weather operation harder.
Our guide on how long a hot water system lasts breaks down what to expect from each technology.
Pairing Your Heat Pump Hot Water System with Solar PV
If you have solar panels, a heat pump hot water system is one of the most effective ways to use your daytime generation. Schedule the system to run during peak solar hours rather than overnight, and you capture two benefits at once: the system operates during the warmest part of the day when efficiency is highest, and it runs on electricity you have generated rather than purchased.
Most mid-range and premium cold-climate units include programmable timers or smart controls to make this easy. We factor solar integration into our recommendations when your roof setup allows it.
Will a Heat Pump Hot Water System Freeze in a Highlands Winter?
No. All modern systems include built-in freeze protection, and the insulated storage tank minimises heat loss overnight. CO₂ units are rated to temperatures far below anything the Highlands experiences, so freeze risk is not a real-world concern with the systems we install.
What can happen with a poorly matched or poorly positioned unit is longer run times in cold conditions, which increases electricity use. That is the practical winter issue to address, and it is solved at the selection and installation stage.
Heat Pump Hot Water vs Gas and Electric: How They Compare for Highlands Homes
Many Highlands homes still run gas or conventional electric hot water. Here is how those options stack up against a cold-climate heat pump in this climate:
| System Type | Winter Performance | Running Cost | Best For |
|---|---|---|---|
| Heat pump (cold-climate CO₂) | Excellent, full efficiency maintained | Lowest year-round | Long-term savings; solar households |
| Heat pump (standard R290) | Reduced, boost element in cold snaps | Moderate, rises in winter | Warmer climates; not suited to Highlands |
| Instantaneous gas (Rinnai) | Consistent year-round | Moderate; tracks gas price movements | High-demand households; no storage needed |
| Conventional electric storage | Consistent but expensive | Highest | Short-term or budget-constrained situations |
Gas delivers consistent winter performance, and Rinnai instantaneous gas is our recommendation when gas is the preferred fuel. Over the medium to long term, though, a properly specified cold-climate heat pump hot water system costs less to run, even accounting for Highlands winters.
For a deeper look at how the two technologies compare on running costs, comfort, and installation, see our full comparison of heat pump vs instantaneous gas.
Government Incentives for Heat Pump Hot Water Upgrades
Upgrading to a heat pump hot water system may make your household eligible for government incentives at the federal and state level. These can reduce your upfront cost meaningfully, but scheme values change regularly, so we do not publish specific figures here.
If you want a broader picture of what a new heat pump hot water system costs, including installation, our guide on hot water installation cost gives a practical breakdown.
Frequently Asked Questions
Do heat pump hot water systems really work in a Southern Highlands winter?
Yes, provided you choose a cold-climate model. Standard R290 units can fall back on their electric boost element when overnight temperatures drop to 2-4°C, negating the efficiency advantage. CO₂-refrigerant units maintain full heat pump performance across all Highlands winter conditions.
How much does a heat pump hot water system cost to run in winter?
Efficiency drops slightly in cold weather, so running costs do increase. A cold-climate CO₂ unit sees a smaller winter rise than a standard model. Even so, year-round costs remain significantly lower than a conventional electric storage system.
How long does it take to heat water on a cold winter morning?
Heat-up times are longer in cold conditions. A well-sized tank addresses this, the system heats water during the day and stores it, so hot water is available on demand regardless of overnight temperatures. We size the tank to your household’s usage.
Can I install a heat pump hot water system indoors to protect it from the cold?
Integrated systems (tank and heat pump combined) can be installed indoors with adequate ventilation, a garage or laundry works well. Split systems mount the heat pump unit outside. We assess your site and recommend the best configuration for your home.
Which brand do you recommend for Highlands homes?
Daikin is our primary recommendation, backed by our Hot Water Specialist appointment and their 10-year parts and labour warranty. Reclaim Energy is a strong alternative if budget is a factor and cold-climate performance is the priority. We match the system to your home rather than apply a one-size recommendation.
Will upgrading my hot water system qualify for government rebates?
It may. Federal and state incentives for energy-efficient hot water upgrades are available and can reduce your upfront cost. Scheme values change, so we provide accurate figures at quote time.