Heat pump hot water. The 2027 replacement decision for any existing system.

Hot water typically represents 15-25% of a household's energy consumption. Heat pump hot water systems use approximately 70% less electricity than equivalent electric storage systems. With substantial state and federal rebates, the 2027 payback period for replacement is typically 3-6 years.

For households with existing electric storage or gas hot water reaching end-of-life, the replacement decision is increasingly straightforward. This post is the 2027 numbers.

How heat pump hot water works

A heat pump hot water system extracts heat from the ambient air and uses it to heat water in a storage tank. The system uses electricity to run the compressor, but for each unit of electricity input, 3-4 units of heat output are produced (the "coefficient of performance" or COP).

By comparison:

• Electric storage: 1 unit of electricity = 1 unit of heat output (COP 1.0)
• Heat pump: 1 unit of electricity = 3-4 units of heat output (COP 3-4)
• Gas storage: 0.6-0.8 units of heat per unit of gas input (depending on efficiency)
• Solar hot water with electric boost: variable depending on solar contribution

The heat pump's coefficient of performance is the central advantage.

Annual energy consumption comparison

For a typical 4-person household with 200L daily hot water usage:

Electric storage (existing system)

• Annual electricity consumption: ~4,500 kWh
• Annual cost at 32 cents/kWh: ~$1,440

Heat pump hot water

• Annual electricity consumption: ~1,200 kWh
• Annual cost at 32 cents/kWh: ~$385
• Annual saving over electric storage: ~$1,055

Gas storage

• Annual gas consumption: ~25,000 MJ
• Annual cost at 4 cents/MJ: ~$1,000

Heat pump compared to gas

• Heat pump electricity cost: ~$385
• Gas alternative cost: ~$1,000
• Annual saving over gas: ~$615

The savings are substantial relative to either electric storage or gas alternatives.

The capital cost

Heat pump hot water system

• Small system (160L): $3,000-4,500
• Medium system (250-280L): $3,500-5,500
• Large system (315-400L): $4,500-7,500
• Installation: $1,000-2,500 (depending on complexity)

Total typical installed cost: $4,500-9,000.

Comparison: electric storage replacement

• Replacement electric storage tank: $1,200-2,500
• Installation: $500-1,200

Total typical: $1,700-3,700.

Cost differential

Heat pump replacement vs electric storage replacement: $2,500-5,500 differential before rebates.

The 2027 rebate landscape

Substantial rebates reduce the effective cost:

Federal Small-scale Technology Certificates (STCs)

STCs generate at installation based on the system's expected emissions reduction over its lifetime. Indicative STC value (mid-2027):

• Small system: $200-400 in STCs
• Medium system: $400-700 in STCs
• Large system: $700-1,200 in STCs

The STC value is typically deducted from the upfront installed price by the installer.

State rebates

State rebates vary substantially:

NSW

• Energy Savings Scheme: rebate available, typically $500-1,800 depending on system and circumstances
• Replace existing gas or electric storage: typically eligible

VIC

• Victorian Energy Upgrades: rebate available, typically $1,000-2,500
• Solar Hot Water Rebate available for solar-electric hybrid systems

QLD

• Limited statewide rebate program
• Some council and retailer-specific programs

WA

• Limited statewide rebate program

SA

• Energy Productivity Program offers rebates for certain installations

ACT

• Sustainable Household Scheme: substantial rebates and interest-free loans

Effective installed cost after rebates

For a typical mid-range heat pump installation (medium system, 250-280L, installed):

NSW indicative

• Headline cost: $5,500
• STC value: -$500
• ESS rebate: -$1,200
• Effective cost: $3,800

VIC indicative

• Headline cost: $5,500
• STC value: -$500
• VEU rebate: -$2,000
• Effective cost: $3,000

Differential vs electric storage replacement

After rebates, heat pump replacement is typically $1,000-2,500 above electric storage replacement.

The payback calculation

For NSW indicative numbers:

• Heat pump effective cost: $3,800
• Electric storage replacement: $2,500
• Heat pump premium: $1,300
• Annual saving over electric: $1,055

Payback on the premium: 1.2 years.

For households with existing electric storage near end of life, the heat pump is a no-brainer replacement decision.

Where heat pumps work best

Three scenarios where heat pumps deliver:

Scenario 1: ambient temperature suits

Heat pumps work best in climates where ambient temperatures are typically 8-30°C. Hot/warm climates (Brisbane, Perth, Adelaide) deliver high COP year-round. Cooler climates (Hobart, Canberra winter) deliver lower COP, but still 2-3x better than electric storage.

Scenario 2: outdoor installation feasible

Heat pumps require outdoor installation (extract heat from outdoor air). Suitable installation locations:

• Outdoor wall mount
• Free-standing on hard surface
• Carport or covered outdoor area

Some heritage and apartment installations may be constrained.

Scenario 3: existing electric storage or gas reaching end-of-life

For end-of-life replacement, the marginal cost premium for heat pump over standard replacement is small after rebates. The annual savings deliver payback within 2-4 years.

Where heat pumps face challenges

Three challenges:

Challenge 1: cold-climate performance

In very cold conditions (overnight winter in Canberra, Hobart, alpine areas), heat pump COP can drop to 2.0 or below. Annual performance is still better than electric storage but the advantage narrows.

Modern cold-climate heat pumps maintain COP 2.5+ at -10°C, but cost more.

Challenge 2: noise

Heat pumps have an outdoor compressor unit that generates noise (similar to air conditioner condenser). Typical 45-55 dB at 1m. Some installations have neighbour noise concerns.

Challenge 3: installation complexity

Some installations require:

• Concrete pad for free-standing unit
• Plumbing relocation
• Electrical upgrade for new circuit
• Body corporate approval (strata buildings)

The installation cost can vary substantially with the complexity.

Integration with solar

Heat pumps integrate well with solar:

Daytime heating

Run the heat pump during daytime (when solar generation peaks) to use solar electricity directly. Hot water tank acts as thermal battery, storing heat for evening use.

Timer or smart controller

Set the heat pump timer to operate during peak solar generation (10am-3pm). Most modern heat pumps have programmable operation.

Combined economic effect

With existing solar, heat pump operating cost can approach zero during sunny periods. Annual operating cost reduced from $385 baseline to $100-200 in solar-equipped households.

The 2027 specific context

Two relevant 2027 developments:

Development 1: gas phase-out

VIC has restricted new gas connections in residential new builds. Other states are considering similar measures. For new builds, electric (heat pump) hot water is increasingly the only option.

Development 2: emissions reductions in operation

As the electricity grid decarbonises, heat pump operation becomes progressively lower-emission. By 2030, most states will be 60%+ renewable, making heat pump hot water effectively zero-emission.

The 2027 heat pump hot water replacement decision is one of the most straightforward energy efficiency upgrades available. The payback is short, the rebates are substantial, and the running cost savings continue for the system's 15-20 year life. For households with end-of-life electric or gas hot water, the decision is rarely about whether to replace with heat pump - it's about which heat pump system and installer to choose.