Instant Gas vs Heat Pump Hot Water Systems: Which Is Better?

Choosing between instant gas and heat pump hot water depends on your home’s energy source, household size, number of bathrooms, available outdoor space, gas type, airflow, budget and whether you prefer continuous flow gas hot water or efficient electric storage. Both systems can suit Australian homes, but they work in very different ways.

At Hot Water Outlet, you can compare instant gas hot water systems, heat pump hot water systems, gas hot water systems, electric hot water systems, hot water systems and common valves, pipework and fittings.

Quick Answer: Is Instant Gas or Heat Pump Hot Water Better?

Instant gas hot water is usually better if your home already has natural gas or LPG, you want continuous flow hot water, and the selected flow rate in L/min suits your household demand.

Heat pump hot water is usually better if you want an efficient electric storage option, do not want to rely on gas, and your property has suitable outdoor space, airflow, drainage and noise conditions.

As a general guide:

• Choose an instant gas hot water system if natural gas or LPG is available and continuous flow hot water suits your home.

• Choose a heat pump hot water system if efficient electric storage is preferred and the property has suitable outdoor space.

• Choose instant gas by flow rate in L/min.

• Choose heat pump by tank capacity in litres.

• Confirm natural gas or LPG before ordering instant gas.

• Check outdoor airflow, noise rating and condensate drainage before ordering heat pump hot water.

• Compare electric hot water systems if a standard electric storage tank is more practical than heat pump.

The better choice is the system that suits your home’s services and location. Instant gas is not automatically better because it is continuous flow, and heat pump is not automatically better because it is efficient. The property needs to suit the system.

Instant Gas vs Heat Pump at a Glance

Both systems can work well, but they solve different problems. Instant gas focuses on on-demand flow. Heat pump focuses on efficient stored hot water.

What Is Instant Gas Hot Water?

An instant gas hot water system heats water as it passes through the unit. It does not store a tank of hot water.

Instant gas is also called continuous flow gas hot water.

Instant gas systems are sized by flow rate in L/min, with common options including:

• 16 L/min

• 20 L/min

• 26 L/min

Instant gas may suit homes where:

• Natural gas or LPG is already available

• Continuous flow hot water is preferred

• A compact external wall-mounted unit suits the property

• The selected flow rate matches household demand

• Gas supply is suitable

• Water pressure and flow are suitable

• The correct natural gas or LPG model is chosen

Instant gas can be a strong option for family homes, two-bathroom homes and properties already set up for gas, but it must be selected carefully.

What Is Heat Pump Hot Water?

A heat pump hot water system uses electricity to draw heat from the surrounding air and transfer it into stored water. It is still a storage system, so it has a tank and is sized by capacity in litres.

Heat pump hot water may suit homes where:

• The current system is electric storage

• Efficient electric hot water is preferred

• Outdoor space is available

• Airflow around the unit is suitable

• Noise can be managed

• Condensate drainage can be handled

• The selected tank capacity suits household demand

• Gas is not available or not preferred

Heat pumps are often compared when replacing older electric storage systems or when a homeowner wants to move away from gas.

Main Difference Between Instant Gas and Heat Pump Hot Water

The main difference is how the system heats and delivers hot water.

Instant gas heats water only when hot water is being used. It uses natural gas or LPG and is sized by flow rate in L/min.

Heat pump hot water heats and stores water in a tank. It uses electricity and is sized by tank capacity in litres.

This means you should not compare a 26 L/min instant gas system directly against a 270L heat pump as though they are the same type of size. They are different measurements for different systems.

Instant Gas Hot Water Pros

Instant gas can be a good choice when the home has suitable gas supply and the selected unit is correctly sized.

Benefits may include:

• Continuous flow hot water where correctly sized

• No large storage tank

• Compact external wall-mounted design

• Available in different flow rates

• Often suitable for homes already using gas

• Commonly compared for two-bathroom homes

• Can suit family homes with higher peak demand

• May be practical when replacing an existing instant gas system

Instant gas is often worth comparing where natural gas or LPG is already available and the household wants continuous flow hot water.

Instant Gas Hot Water Cons

Instant gas is not suitable for every property.

Potential drawbacks include:

• Requires natural gas or LPG

• Natural gas and LPG models are not interchangeable

• Gas supply must suit the selected unit

• Flow rate must match household demand

• Water pressure and flow can affect performance

• A lower-flow unit may not suit larger homes

• External location requirements must be suitable

• Gas and plumbing work must be completed by licensed tradespeople

The main mistake is choosing an instant gas system by price alone without checking gas type, flow rate, gas supply and peak household demand.

Heat Pump Hot Water Pros

Heat pump hot water can be a strong choice where efficient electric storage is preferred and the property suits the system.

Benefits may include:

• Efficient electric hot water option

• Does not require natural gas or LPG

• Useful replacement pathway from electric storage

• Can suit families when correctly sized

• Can suit homes moving away from gas appliances

• Available from recognised hot water brands

• May suit homes with solar power where the setup is planned properly

• May be compared with rebates or incentives where current schemes apply

Heat pump hot water is most attractive when the household has regular hot water demand and the property has the right outdoor location.

Heat Pump Hot Water Cons

Heat pump hot water is not suitable for every property.

Potential drawbacks include:

• Usually higher upfront product price than standard electric storage

• Needs suitable outdoor space

• Needs airflow around the unit

• Needs noise placement planning

• Needs condensate drainage

• May not suit tight side passages or enclosed areas

• May not suit some units or townhouses

• Larger tanks may need more access and delivery planning

The main mistake is choosing a heat pump because it sounds efficient without checking airflow, location, tank size and noise conditions.

Which Is Better for Continuous Hot Water?

Instant gas is usually the better option if your main priority is continuous flow hot water and the property has suitable natural gas or LPG.

Instant gas does not store hot water in a tank, so it does not run out of stored hot water in the same way a storage system can. However, it still needs the right flow rate.

For continuous flow performance, check:

• Flow rate in L/min

• Natural gas or LPG model

• Gas supply suitability

• Water pressure and flow

• Number of bathrooms

• Whether outlets may run together

• Shower habits

• Controller compatibility

A 26 L/min instant gas unit may be worth comparing for larger homes, but the gas supply and water pressure still need to be suitable.

Which Is Better for Energy Efficiency?

Heat pump hot water is usually the better option to compare if your priority is efficient electric hot water.

A heat pump may suit energy-focused buyers where:

• Outdoor space is available

• Airflow is suitable

• Noise can be managed

• The tank capacity suits household demand

• The home uses hot water regularly

• The property is replacing old electric storage

• The household wants to compare electric options instead of gas

However, efficiency depends on the system being properly located and correctly sized. A heat pump in a poor location may not perform as expected.

Which Is Cheaper: Instant Gas or Heat Pump?

The cheaper option depends on the specific product, brand, size, system type, accessories and whether you are comparing supply-only product pricing or full installed cost.

Instant gas pricing depends on:

• Flow rate in L/min

• Brand

• Natural gas or LPG model

• Controller compatibility

• Product specifications

• Required valves and fittings

Heat pump pricing depends on:

• Tank capacity

• Brand

• Product design

• Dimensions

• Warranty information

• Rebate eligibility where relevant

• Required valves and fittings

Hot Water Outlet sells supply-only hot water systems and accessories online. Supply-only pricing usually does not include installation, plumbing, gas fitting, electrical work, old unit removal, disposal, valves, fittings, pipework changes or compliance upgrades unless clearly stated.

Which Has Lower Running Costs?

Running costs depend on energy tariffs, gas type, electricity rates, household usage, system size, product design, location and how well the system suits the property.

As a general guide:

• Heat pump hot water is commonly compared for efficient electric hot water.

• Instant gas heats water on demand using natural gas or LPG.

• Gas prices and electricity prices vary.

• Household usage patterns affect the result.

• Oversizing or undersizing can reduce value.

• Poor heat pump location can affect performance.

• Too-low instant gas flow rate can affect comfort.

Do not choose based only on running cost assumptions. Correct sizing and site suitability matter heavily.

Instant Gas vs Heat Pump for Small Homes

Small homes can suit either system depending on available services and space.

Instant gas may suit a small home if:

• Natural gas or LPG is already available

• A compact wall-mounted system is preferred

• One bathroom is used most of the time

• A 16 L/min or 20 L/min system suits demand

• External wall location is suitable

Heat pump may suit a small home if:

• The home is electric-focused

• Outdoor space is available

• Airflow is suitable

• Noise can be managed

• The tank capacity is not oversized

• The household uses hot water regularly

For small homes, do not choose the smallest or cheapest system automatically. The system still needs to match real usage.

Instant Gas vs Heat Pump for Units

Units can be more restricted because body corporate rules, external wall access, outdoor space and noise requirements may affect both options.

Instant gas may suit a unit if:

• The building already supports gas hot water

• Natural gas or LPG is confirmed

• External location requirements can be met

• Body corporate or building rules allow it

• The selected flow rate suits demand

Heat pump may suit a unit only if:

• Outdoor space is available

• Airflow is suitable

• Noise requirements can be met

• Condensate drainage is possible

• Body corporate rules allow it

• Product dimensions and access work

For many units, the existing system type and building requirements are the best starting point.

Instant Gas vs Heat Pump for Townhouses

Townhouses may suit instant gas or heat pump depending on layout, services and outdoor space.

Instant gas may suit a townhouse if:

• Natural gas or LPG is already available

• A compact external wall-mounted unit fits

• A 20 L/min or 26 L/min system suits demand

• Gas supply can support the system

• Body corporate or complex rules allow it

Heat pump may suit a townhouse if:

• There is suitable outdoor space

• Airflow is available

• Noise can be managed

• Condensate drainage is suitable

• Delivery access works

• The tank capacity suits household demand

For townhouses, neighbours can be close and outdoor areas can be tight, so noise, clearance and location are important.

Instant Gas vs Heat Pump for Family Homes

Family homes usually need more careful hot water sizing because peak demand can be high.

Instant gas may suit a family home if:

• Natural gas or LPG is available

• Continuous flow hot water is preferred

• A 20 L/min or 26 L/min model suits demand

• Two bathrooms may be used close together

• Gas supply and water pressure are suitable

Heat pump may suit a family home if:

• The tank capacity suits daily demand

• Outdoor space and airflow are suitable

• Noise placement can be managed

• The household wants efficient electric storage

• The home is replacing electric storage or moving away from gas

For families, the better option depends on number of bathrooms, shower timing, bath use, laundry demand and available services.

Instant Gas vs Heat Pump for One Bathroom

A one-bathroom home may suit either instant gas or heat pump.

Instant gas may suit if:

• Natural gas or LPG is available

• A 16 L/min or 20 L/min model suits demand

• A compact external unit is preferred

• The household wants continuous flow hot water

Heat pump may suit if:

• Outdoor space is available

• Airflow is suitable

• The household wants efficient electric storage

• The tank capacity suits daily use

• The home is replacing electric storage

One bathroom does not automatically mean low demand. A one-bathroom family home may still need a capable system.

Instant Gas vs Heat Pump for Two Bathrooms

Two-bathroom homes need more careful sizing because demand may overlap.

Instant gas may suit two bathrooms if:

• Natural gas or LPG is available

• A 20 L/min or 26 L/min model suits demand

• Gas supply and water pressure are suitable

• Two showers may run close together

• Continuous flow hot water is preferred

Heat pump may suit two bathrooms if:

• The tank capacity supports two-bathroom demand

• Outdoor space and airflow are suitable

• Noise placement is acceptable

• The household wants efficient electric storage

• The property has suitable drainage and access

For two bathrooms, compare peak demand carefully. Instant gas needs enough flow rate. Heat pump needs enough stored capacity.

Instant Gas vs Heat Pump for Rental Properties

Rental properties need practical hot water systems that suit likely tenant demand.

Instant gas may suit a rental if:

• Natural gas or LPG is available

• Flow rate suits the number of bedrooms and bathrooms

• A compact external unit is practical

• Gas supply and water pressure are suitable

• Existing gas services are already in place

Heat pump may suit a rental if:

• Outdoor location is suitable

• Airflow and noise conditions are acceptable

• Tank capacity suits likely tenants

• The owner wants to compare efficient electric hot water

• The property currently uses electric storage

Avoid undersizing rental hot water. A cheaper system can create tenant complaints if it cannot keep up.

Instant Gas vs Heat Pump for Renovations

Renovations are a good time to reassess hot water because system location, bathroom count and household demand may change.

Instant gas may suit a renovation if:

• Natural gas or LPG is available

• A wall-mounted external unit suits the new layout

• A second bathroom is being added

• Continuous flow hot water is preferred

• Gas supply can support the selected flow rate

Heat pump may suit a renovation if:

• Outdoor location can be planned early

• Airflow and drainage can be allowed for

• The renovation increases hot water demand

• The home is moving toward electric appliances

• The tank capacity suits the finished home

Plan the hot water system around the finished home, not the old system.

Instant Gas vs Heat Pump With Solar Power

Some homeowners compare instant gas and heat pump hot water because they already have solar power or want to use more electric appliances.

Heat pump hot water may be worth comparing with solar where:

• The system can be timed or managed appropriately

• Outdoor space and airflow are suitable

• The selected model supports the intended setup

• The household uses hot water regularly

• Licensed tradespeople confirm electrical suitability

Instant gas may still suit homes that already have natural gas or LPG and want continuous flow hot water.

Do not assume solar automatically makes one option best. Tariffs, timing, product suitability and household demand all matter.

Heat Pump Rebates vs Instant Gas Pricing

Some heat pump hot water systems may be eligible for rebates or incentives depending on current program rules, product eligibility, installer requirements, property details and state or territory.

Rebates can change, so they should not be assumed.

Before relying on a rebate, check:

• Current state or territory rules

• Product eligibility

• Installer requirements

• Customer eligibility

• Whether the program is still active

• Whether the product price already includes rebate assumptions

• Whether the system must be installed by an approved provider

A rebate can improve heat pump value, but it does not make every heat pump suitable. Location, airflow, tank size and household demand still matter.

Natural Gas vs LPG for Instant Gas

If choosing instant gas, gas type must be confirmed before ordering.

Instant gas systems may be:

• Natural gas

• LPG

Natural gas and LPG systems are not interchangeable.

Before ordering, check:

• Current gas hot water unit label

• Gas meter

• LPG bottle setup

• Existing appliance details

• Product listing gas type

• Licensed gas fitter advice if unsure

Choosing the wrong gas type can cause delays, compatibility problems and extra costs.

Gas Supply and Water Pressure for Instant Gas

Instant gas performance depends on the unit, the gas supply and the property’s water flow.

Before choosing instant gas, check:

• Existing gas line sizing

• Distance from gas supply

• Other gas appliances

• Regulator setup

• Natural gas or LPG setup

• Water pressure

• Shower flow rates

• Number of outlets

• Whether multiple fixtures run together

• Product specifications

A larger instant gas unit may not perform properly if the property cannot support it. A licensed gas fitter or plumber should assess the setup where needed.

Outdoor Space and Airflow for Heat Pump

Heat pumps need suitable outdoor space and airflow.

Before choosing a heat pump, check:

• Outdoor space

• Airflow around the unit

• Clearance from walls and fences

• Noise rating

• Distance from bedrooms

• Distance from neighbours

• Condensate drainage

• Delivery access

• Product dimensions

• Base or platform requirements

• Connection positions

• Electrical requirements

A heat pump with the right tank size can still be unsuitable if the location is poor.

Noise and Drainage for Heat Pump

Heat pumps make operating noise and produce condensate during operation.

Before ordering, consider:

• Whether the system is near bedrooms

• Whether the system is near neighbours

• Whether the system is near outdoor living areas

• How condensate will drain

• Whether drainage could create wet areas

• Whether the outdoor location is enclosed

• Whether body corporate rules apply

Noise and drainage are not minor details. They can determine whether heat pump hot water is practical for the property.

Tank Capacity vs Flow Rate

Heat pump and instant gas systems are sized differently.

Heat pump systems use tank capacity in litres.

Instant gas systems use flow rate in L/min.

Before choosing, check:

• Number of people in the home

• Number of bathrooms

• Number of showers per day

• Whether showers happen back-to-back

• Bath use

• Kitchen use

• Laundry use

• Whether outlets run at the same time

• Current system size or flow rate

• Whether the current system keeps up

• Available energy source

• Product specifications

Do not compare heat pump litres and instant gas L/min as if they are the same measurement.

Should You Replace Instant Gas With Heat Pump?

Replacing instant gas with heat pump may be worth comparing if the property wants to move away from gas or use electric hot water.

A heat pump may be worth considering if:

• Outdoor space is available

• Airflow is suitable

• Noise can be managed

• Condensate drainage can be handled

• Tank capacity suits household demand

• Electrical requirements can be met

• The household wants efficient electric storage

Instant gas may remain more practical if:

• The existing instant gas system works well

• Natural gas or LPG is available

• Gas supply suits the selected model

• Continuous flow hot water is preferred

• Heat pump location is not suitable

Changing energy source can involve extra plumbing, gas or electrical work. Licensed tradespeople should assess suitability.

Should You Replace Heat Pump With Instant Gas?

Replacing a heat pump with instant gas may be considered only where natural gas or LPG is available and the property suits gas hot water.

Before changing from heat pump to instant gas, check:

• Natural gas or LPG availability

• Gas supply suitability

• External wall location

• Household hot water demand

• Required flow rate in L/min

• Water pressure and flow

• Required valves and fittings

• Licensed gas fitting requirements

If gas is not already available, replacing a heat pump with instant gas may add complexity and cost.

Should You Choose Instant Gas?

Instant gas may be the better choice if the property already has gas and the household wants continuous flow hot water.

Instant gas may suit when:

• Natural gas or LPG is available

• Flow rate matches demand

• External wall location is suitable

• Gas supply can support the selected unit

• Water pressure and flow are suitable

• The household wants a compact wall-mounted system

• The home has higher peak hot water demand

Do not choose instant gas only because it does not store water. Choose it because the home suits it.

Should You Choose Heat Pump?

Heat pump may be the better choice if the property suits electric storage and the household wants an efficient option.

Heat pump may suit when:

• Gas is not available or not preferred

• Outdoor space and airflow are suitable

• Noise placement is acceptable

• Condensate drainage can be managed

• Tank capacity suits demand

• The home is replacing electric storage

• Energy efficiency is a priority

Do not choose heat pump only because of efficiency claims. Choose it because the location and tank capacity suit the home.

Valves, Fittings and Accessories

Instant gas and heat pump hot water systems may need valves, fittings or accessories as well as the main unit.

Common items include:

• Tempering valves

• Pressure relief valves

• Duo valves

• Non-return valves

• Isolation valves

• Copper pipework

• Fittings

• Controller accessories for instant gas

• Thermostats

• Elements

• Connection parts

Hot Water Outlet has a dedicated range of valves, pipework and fittings to help customers compare common hot water accessories.

Always confirm compatibility before ordering.

Common Mistakes When Comparing Instant Gas and Heat Pump Hot Water

Comparing L/min to Litres

Instant gas uses flow rate in L/min. Heat pump uses tank capacity in litres. These are different sizing methods.

Choosing Instant Gas Without Confirming Gas Type

Natural gas and LPG systems are different. Always choose the correct model.

Choosing Heat Pump Without Checking Airflow

Heat pumps need outdoor space and airflow. A tight or enclosed location may be unsuitable.

Choosing Too-Low Instant Gas Flow Rate

A 16 L/min unit may not suit families, two bathrooms or overlapping hot water use.

Choosing Too-Small Heat Pump Capacity

A small heat pump may run out if household demand is high.

Ignoring Noise Placement

Heat pumps make operating noise, so placement near bedrooms and neighbours should be checked.

Choosing by Price Alone

The cheapest product may not suit the home’s energy source, location or demand.

Forgetting Valves and Fittings

The main system may not be the full order. Accessories may also be needed.

Instant Gas vs Heat Pump Buyer Checklist

Before choosing between instant gas and heat pump hot water, check:

• Current hot water system type

• Current brand and model

• Current tank capacity or flow rate

• Whether the current system keeps up

• Electricity, natural gas or LPG

• Number of people in the home

• Number of bathrooms

• Number of showers per day

• Whether outlets are used at the same time

• Bath use

• Kitchen hot water use

• Laundry use

• Desired system type

• Flow rate in L/min if instant gas

• Tank capacity if heat pump

• Gas supply suitability if choosing instant gas

• Water pressure and flow

• Outdoor space if choosing heat pump

• Airflow if choosing heat pump

• Noise rating if choosing heat pump

• Condensate drainage if choosing heat pump

• Electrical requirements if choosing heat pump

• Product dimensions

• Connection positions

• Required valves and fittings

• Delivery access

• Warranty information

• Product specifications

• Rebate eligibility if relevant

Compare Instant Gas and Heat Pump Hot Water Online

Hot Water Outlet makes it easier to compare instant gas and heat pump hot water systems by type, size, energy source, brand and product specifications.

Start with:

• Instant Gas Hot Water Systems

• Heat Pump Hot Water Systems

• Gas Hot Water Systems

• Electric Hot Water Systems

• Hot Water Systems

• Valves, Pipework and Fittings

FAQs About Instant Gas vs Heat Pump Hot Water

Is instant gas better than heat pump hot water?

Instant gas may be better if your home already has natural gas or LPG, continuous flow hot water is preferred, and the selected flow rate suits demand. Heat pump may be better if efficient electric storage is preferred and the property has suitable outdoor space and airflow.

Is heat pump better than instant gas?

Heat pump hot water may be better where gas is not available or not preferred, the home has outdoor space, and efficient electric storage is the priority. Instant gas may be better where gas is already available and continuous flow hot water suits the household.

Does instant gas run out of hot water?

Instant gas does not run out of stored hot water because it does not use a storage tank. However, the flow rate still needs to match household demand.

Can a heat pump run out of hot water?

Yes. Heat pump hot water systems store hot water in a tank and can run out if the tank is undersized or household demand is high.

Is 26L instant gas better than a heat pump?

A 26 L/min instant gas system may suit larger gas-connected homes with higher peak demand, but a heat pump may suit homes wanting efficient electric storage. They are different system types, so the best choice depends on the property.

Is heat pump cheaper to run than instant gas?

Running costs depend on electricity tariffs, gas tariffs, gas type, household use, product efficiency, climate, system size and installation quality. Compare based on the specific property and household.

Should I replace instant gas with heat pump?

Replacing instant gas with a heat pump may be worth comparing if the property wants electric hot water and has suitable outdoor space, airflow, drainage and electrical requirements.

Should I replace heat pump with instant gas?

Replacing a heat pump with instant gas may be considered only where natural gas or LPG is available and the property has suitable gas supply, water pressure and external wall location.

Do instant gas and heat pump systems need valves and fittings?

Some replacements require valves, fittings or pipework depending on system type, pressure rating and connection layout. Browse valves, pipework and fittings and confirm compatibility before ordering.

Can I install instant gas or heat pump hot water myself?

No. Hot water systems involve plumbing, gas and electrical work that should be completed by appropriately licensed tradespeople. Hot Water Outlet sells supply-only hot water systems and accessories online, and may help organise quotes from reputable installers where appropriate.

Find the Right Instant Gas or Heat Pump Hot Water System

The right choice between instant gas and heat pump hot water depends on your energy source, household demand, available space and replacement setup. Instant gas may suit homes with natural gas or LPG that want continuous flow hot water. Heat pump hot water may suit homes wanting efficient electric storage where outdoor space and airflow are suitable.

Browse instant gas hot water systems and heat pump hot water systems online with Hot Water Outlet to compare hot water options by brand, size and product specifications.