Heat Pump to Gas Hot Water
Heat Pump to Gas Hot Water: Should You Switch?
Instant gas can remove the tank and gas storage can deliver strong recovery — but switching fuel type is not automatically an upgrade.
A heat pump can be replaced with either instant gas or gas storage where the property has a suitable natural-gas or LPG supply. The conversion changes the home's energy source, installation requirements and running-cost profile. Gas can solve specific problems such as limited tank space, noise sensitivity or a preference for continuous-flow hot water, but if the existing heat-pump location still works, compare a replacement heat pump before giving up its lower energy consumption and ability to use rooftop solar.
Does Switching to Gas Make Sense?
Gas can be the right answer for specific properties. Start with why you want to leave heat pump and whether usable gas is already available.
1 Why are you considering gas?
2 What gas supply is already available?
3 What matters most long term?
Guide only. Gas availability, pipe sizing, LPG or natural-gas compatibility, appliance location, ventilation, clearances, hot-water demand and the existing heat-pump installation all need to be checked.
Can You Replace a Heat Pump With Gas Hot Water?
Yes. A heat-pump hot-water system can be replaced with either instant gas or gas storage where a suitable natural-gas or LPG supply is available. Instant gas removes the storage cylinder and heats water on demand, while gas storage retains a tank but uses a gas burner for recovery. The main question is whether the advantages of changing to gas justify giving up the heat pump's lower energy consumption, solar compatibility and existing electrical infrastructure.
Gas Supply
Natural gas or LPG needs to be available in the correct configuration and with enough capacity for the selected appliance.
Gas Type
Natural-gas and LPG appliances are not automatically interchangeable. The exact model needs to match the property's fuel supply.
Location
Gas appliances have their own installation, clearance, ventilation, flue and access requirements depending on the system type and location.
Energy Source Changes
Water heating moves from efficient electric heat transfer to combustion of natural gas or LPG.
If You Leave Heat Pump, Which Gas System Would You Choose?
"Switching to gas" can mean two very different things. Instant gas removes stored hot water altogether, while gas storage keeps the familiar cylinder format but changes the way the water is reheated.
Remove the Storage Tank
Instant gas heats water as it passes through the appliance. A correctly sized system can continue heating while hot water is being drawn rather than relying on a stored reserve.
It can be attractive where freeing up the heat-pump tank space is important or where the household particularly values continuous-flow delivery.
The existing gas supply must have enough capacity and the gas pipework may need alteration or upgrading for the selected unit.
Keep Stored Hot Water
Gas storage keeps a cylinder of hot water available and uses a gas burner to recover the tank as water is consumed.
Strong recovery can make it practical for households with concentrated periods of hot-water demand, but stored gas systems also carry standing heat losses.
Tank size, burner recovery and first-hour delivery should be considered together rather than choosing from litres alone.
Why Would Someone Change From Heat Pump to Gas?
Heat pump is normally chosen for efficiency, so moving back to gas should usually solve a specific problem rather than simply being a reaction to one failed appliance.
Remove the Storage Tank
Instant gas can free the physical area occupied by a large heat-pump cylinder and suit properties where ground space has become valuable.
Continuous-Flow Preference
A correctly sized instant gas system provides on-demand heating rather than relying on a finite volume of stored hot water.
Heat-Pump Noise Cannot Be Solved
Where the only practical heat-pump position is genuinely noise sensitive and relocation or a quieter model will not solve the problem, gas may offer another pathway.
Heat Pump, Instant Gas & Gas Storage: Current JR Starting Prices
Compare the complete installed job, not just the appliance. A fuel conversion can require gas pipework, regulators, LPG infrastructure, relocation or changes that do not apply when replacing a heat pump with another heat pump.
Keeps the home's efficient electric hot-water pathway and may reuse much of the existing position, plumbing and electrical infrastructure.
Current JR advertised starting price. Eligible heat pumps may qualify for JR's applicable upfront STC pathway.
Compact continuous-flow hot water without a storage tank, subject to suitable gas availability and gas-line capacity.
Current JR advertised starting price. Conversion costs can change with gas pipework, gas type and installation location.
Retains stored hot water with gas-fired recovery and can suit properties already configured for a suitable gas-storage installation.
Current JR advertised starting price. Final pricing depends on gas type, recovery, tank capacity and conversion scope.
Heat Pump vs Instant Gas vs Gas Storage
| Consideration | Heat Pump | Instant Gas | Gas Storage |
|---|---|---|---|
| Energy source | Electricity + heat from surrounding air | Natural gas or LPG | Natural gas or LPG |
| Hot-water delivery | Stored water + heat-pump recovery | Heated on demand | Stored water + burner recovery |
| Physical footprint | Storage tank required | Compact wall-mounted appliance | Storage tank required |
| Energy use / running-cost direction | Very efficient and generally low running cost | Gas consumption whenever hot water flows | Gas consumption plus stored-water heat loss |
| Rooftop solar PV | Can use household solar-generated electricity | PV does not power the gas burner | PV does not power the gas burner |
| Noise | Compressor and fan operate during heating | Burner and fan noise varies by model | Burner operation |
| STC pathway | Eligible listed replacement systems may qualify | No heat-pump STC pathway | No heat-pump STC pathway |
| Strongest reason to choose | Long-term efficiency and solar compatibility | Compact footprint and continuous flow | Stored reserve with strong gas recovery |
Do You Already Have Enough Gas Supply for the New System?
Having a gas cooktop or another small gas appliance does not automatically mean the existing gas pipework can supply a large hot-water appliance. Available fuel type, pipe size, pressure, regulator capacity and the demand from other appliances all matter.
Existing Natural Gas
Where the property already has reticulated natural gas, the existing meter and pipework still need to be checked against the gas input required by the selected hot-water system.
Existing LPG
LPG hot water requires an LPG-compatible appliance and a suitable cylinder, regulator and pipework arrangement capable of supplying the system.
No Gas Currently
If the home currently relies entirely on electricity, introducing gas solely for hot water adds another fuel source and additional installation infrastructure. In this situation, staying with heat pump is usually worth comparing very closely.
Heat Pump to Instant Gas: What Actually Changes?
This is the bigger physical change of the two gas pathways. The storage cylinder disappears and the new appliance heats water only when it is required.
Storage Tank Is Removed
The old heat-pump cylinder is removed, potentially freeing a significant amount of ground-level space.
Hot-Water Pipework May Move
The best instant-gas position may not be where the existing heat-pump tank stands, so hot and cold pipework can require alteration.
Gas Pipework Is Introduced or Checked
The selected unit needs enough gas supply under operating conditions while other connected appliances are also considered.
Flow Rate Replaces Tank Size
Instead of choosing litres of stored water, system selection focuses on simultaneous outlet demand, required flow and available gas supply.
Continuous Delivery Changes Usage
The household is no longer limited by the amount of hot water stored in a tank, provided the appliance can meet the flow demand and fuel supply remains available.
Solar PV Stops Heating the Water
The home's solar electricity may still power other appliances, but it cannot supply the gas burner that now provides the water-heating energy.
Heat Pump to Gas Storage: What Actually Changes?
Physically, this can look more familiar because both systems use a tank. The major change is the energy source and recovery method.
Existing Position May Help
A suitable outdoor heat-pump location may provide enough physical space for a gas-storage cylinder, subject to gas-system clearance and installation requirements.
Burner Recovery Replaces Heat-Pump Recovery
Gas storage can reheat stored water quickly, so tank capacity and burner recovery need to be assessed together.
Gas Supply Becomes Critical
Natural gas or LPG pipework needs sufficient capacity for the burner and any other appliances operating at the property.
Storage Loss Remains
Like any storage system, hot water loses heat while sitting in the cylinder. Gas storage also needs to accommodate the burner and combustion arrangement.
Solar PV Benefit Is Lost
A gas-storage burner cannot make direct use of the household's excess rooftop-solar electricity for water heating.
Recovery Can Be a Strength
Strong burner recovery can suit households with concentrated hot-water demand where that characteristic is more important than minimum energy consumption.
Have Rooftop Solar? Think Carefully Before Moving Hot Water Back to Gas
A heat pump is one of the household loads that can make productive use of daytime rooftop-solar generation. Once hot water is moved to gas, the home's PV system can no longer provide the primary energy used by the hot-water appliance.
Heat Pump + Solar
The heat pump can be scheduled into daylight hours so household-generated electricity contributes directly to water heating.
Instant Gas + Solar
Solar PV continues powering the rest of the home, but hot-water heating itself is supplied by the gas burner when taps are opened.
Gas Storage + Solar
The stored water is heated by gas rather than excess PV, so one of the home's useful opportunities for daytime solar consumption is removed.
If a home already has rooftop solar and the existing heat-pump location is suitable, we would generally want a clear practical reason before recommending that hot-water energy move back to gas.
If Your Heat Pump Failed, Does That Mean You Should Go Back to Gas?
Not necessarily. A failed appliance and a failed technology are different things. Heat pumps vary substantially in design, component quality, operating noise, recovery, controls, warranty support and serviceability.
The Existing Site Is Already Proven
If the heat pump operated successfully in its current location for years, the property has already demonstrated that it can physically accommodate the technology.
Plumbing Is Already There
Hot and cold water services, drainage and the tank position may already suit another heat-pump installation with comparatively little redesign.
Electrical Infrastructure Exists
The home already has electrical infrastructure associated with the existing heat pump, although the exact replacement requirements still need to be checked.
Switching to Gas Also Means Giving Up the Heat-Pump STC Pathway
Eligible air-source heat pumps can generate Small-scale Technology Certificates when the exact model and completed installation satisfy the current scheme requirements. Conventional gas hot-water systems do not receive heat-pump STCs.
Eligible Systems Can Receive the JR Upfront STC Pathway
Where the new system and completed installation qualify, JR currently applies its flat $1,000 including GST upfront STC discount under the applicable assignment requirements.
No Heat-Pump STC Offset
Moving to instant gas or gas storage means the replacement is no longer an eligible air-source heat-pump installation, so that heat-pump incentive pathway no longer applies.
When Changing From Heat Pump to Gas Can Genuinely Make Sense
Gas should solve something useful. There are situations where one of the gas pathways can suit the property better than forcing another heat pump into the same problem.
You Need the Tank Space Back
Instant gas can remove the large storage cylinder completely and is one of the clearest reasons a homeowner may intentionally move away from heat pump.
Continuous Flow Is a Priority
A suitable instant gas system can appeal where the household specifically wants on-demand heating rather than managing stored capacity and recovery.
Heat-Pump Noise Cannot Be Managed
If relocation and quieter heat-pump models cannot provide an acceptable outcome, gas can remove the heat-pump compressor from that location.
Gas Is Already Well Established
Where the property already has a suitably sized natural-gas or LPG installation, the conversion can be substantially easier than introducing gas to an all-electric home.
Strong Recovery Is More Important Than Efficiency
A properly sized gas-storage system can provide strong recovery for households with concentrated periods of high hot-water demand.
Property Constraints Favour Gas
Specific space, airflow, access or installation limitations can occasionally make an alternative gas configuration more practical than another heat pump.
When We Would Usually Stay With Heat Pump
If the existing heat-pump installation has worked satisfactorily and the motivation for switching is mainly that the appliance has reached the end of its life, there is usually a strong case for comparing another heat pump first.
No Gas Supply Exists
Introducing a second household energy source solely for water heating adds infrastructure that a replacement heat pump does not require.
Rooftop Solar Is Installed
Heat pump can directly use household solar electricity for water heating; gas systems cannot use that PV generation for their burner energy.
Lowest Long-Term Energy Use Matters
Heat pumps remain one of the lowest-energy mainstream hot-water technologies when correctly selected and installed.
Existing Position Works
Airflow, tank space, plumbing, electrical supply and drainage may already be solved for the next heat pump.
The Home Has Solar + Battery
Efficient daytime hot-water heating can make useful use of solar generation while leaving gas completely out of the water-heating equation.
Eligible STCs Reduce the Upfront Gap
Where an eligible replacement qualifies, the available heat-pump STC pathway can reduce the difference between staying heat pump and changing technologies.
How a Heat-Pump-to-Gas Conversion Works
Confirm Why You Are Changing
Determine whether the issue is the individual heat pump, tank space, noise, recovery or a genuine preference for gas.
Choose Instant or Storage Gas
Decide whether the priority is tank-free continuous flow or stored hot water with gas-fired recovery.
Check Gas Availability
Confirm natural gas or LPG type, regulator, meter or cylinder arrangement, pipe size and available capacity.
Confirm the Installation Position
Check clearances, ventilation, flue requirements where applicable, plumbing routes, drainage and service access.
Remove the Heat Pump
The existing heat pump is isolated, drained and removed, with its electrical and plumbing services altered for the new installation as required.
Install & Commission Gas
The selected gas appliance is connected, tested and commissioned with the required licensed plumbing and gas work completed.
Heat Pump to Gas Hot Water FAQs
Can I replace a heat-pump hot-water system with gas?
Yes. A heat pump can be replaced with either instant gas or gas storage where a suitable natural-gas or LPG supply is available. Gas supply capacity, installation position, plumbing and the selected appliance all need to be checked.
Is switching from heat pump to gas a good idea?
It can make sense where gas solves a specific issue such as removing the storage tank, providing continuous-flow hot water or overcoming a heat-pump location problem. If the existing heat-pump position remains suitable and lower long-term energy use matters, another heat pump should normally be compared first.
Should I choose instant gas or gas storage?
Instant gas is generally the stronger gas option where a compact footprint and continuous-flow delivery are the priority. Gas storage provides a stored reserve combined with burner recovery and can suit households that prefer traditional stored hot water.
Can instant gas replace my heat-pump tank?
Yes. The heat-pump tank can be removed and a suitable continuous-flow gas system installed in an appropriate location. The property's gas supply must have enough capacity for the selected unit and the plumbing may need to be redirected.
Can gas storage go where my heat pump is now?
Sometimes. An existing outdoor storage position may provide enough room, but the location still needs to satisfy the requirements of the selected gas-storage appliance, including gas supply, clearances, combustion and service access.
Do I need natural gas already connected?
No, because suitable LPG systems are also available. However, if neither natural gas nor LPG infrastructure currently exists, adding gas solely for hot water introduces additional installation requirements that should be compared against simply replacing the heat pump.
Can the existing gas line from my cooktop supply instant gas hot water?
It should not be assumed. Instant gas hot-water systems can have substantial gas demand, so gas pipe sizing, available pressure, regulator or meter capacity and other connected appliances need to be assessed.
Is instant gas cheaper to run than a heat pump?
Heat pumps are generally among the lowest-running-cost mainstream hot-water systems because they transfer heat rather than generating all of it from purchased fuel. Actual household costs still depend on gas and electricity tariffs, solar PV, hot-water use and system performance.
Is gas storage cheaper to run than a heat pump?
Gas storage provides strong recovery but also maintains a stored volume of hot water and uses gas combustion for reheating. Where energy efficiency and long-term running cost are the priority, heat pump should normally be compared before changing to gas storage.
What if my heat pump only failed once?
One failed heat pump does not necessarily mean heat-pump technology is unsuitable for the property. If the installation position remains suitable, compare current replacement models by reliability, warranty, noise, recovery, support and installed price before changing fuel type.
Is gas better if I want endless hot water?
A correctly sized instant gas system can continue heating while hot water is flowing, making it attractive for households specifically wanting continuous-flow delivery. Available gas supply and simultaneous flow demand still limit actual performance.
What happens to my rooftop solar if I switch to gas hot water?
The solar PV system continues powering the home's electrical loads, but it can no longer supply the primary energy used to heat water once the hot-water appliance uses a gas burner instead of electricity.
Do I lose heat-pump STCs if I switch to gas?
Gas hot-water systems do not receive the air-source heat-pump STC pathway. An eligible replacement heat pump may qualify when the exact model and completed installation satisfy current Small-scale Technology Certificate requirements.
Should I replace a failed heat pump with another heat pump instead?
If the existing location works, lower energy consumption matters and there is no strong reason to change fuel type, another heat pump should normally be compared first. Much of the tank position, plumbing and electrical infrastructure may already suit the replacement.
Thinking About Leaving Heat Pump? Compare the Complete Gas Conversion First
Instant gas can provide compact continuous-flow hot water and gas storage can provide strong stored recovery. If your existing heat-pump location still works, though, compare a modern replacement heat pump against the complete gas conversion — including fuel availability, pipework, installation, running costs, rooftop solar use and any eligible STC benefit.