Hot Water System Install: What to Check Before Ordering or Replacing Your Unit

Oct 25, 2024

A hot water system install is not just a matter of buying a new unit and connecting a few pipes. The right system needs to suit your household size, energy source, installation location, access, water pressure, electrical requirements, gas type, drainage, valves and compliance requirements.

Electric storage, gas storage, instant gas, instant electric, heat pump and solar hot water systems all have different installation needs. A simple like-for-like replacement can be very different from changing system type, moving the unit, upgrading to heat pump hot water or switching from storage to instant gas.

Installed Today makes it easy to compare and order hot water systems online, including electric hot water systems, gas hot water systems, instant gas hot water systems and heat pump hot water systems. Supply-only ordering is available across major Australian metro areas, with selected supplied-and-installed options available on eligible products in Brisbane and Gold Coast service areas.

Quick Answer: What Should You Know Before a Hot Water System Install?

Before installing a hot water system, confirm the system type, size, energy source, access, valves, drainage and compliance requirements.

As a general guide:

Electric storage systems need the right tank size, electrical supply, valves and drainage
Gas systems need the correct gas type, licensed gas fitting, ventilation, clearances and water pressure checks
Instant gas systems need gas pipe sizing and flow rate checks, especially for 26L units
Heat pump systems need outdoor airflow, condensate drainage, access, electrical suitability and sensible noise placement
Solar hot water systems need roof suitability, collector placement, booster planning and installer confirmation
Instant electric systems need electrical capacity checks before ordering
Supply-only pricing usually covers the product only
Supplied-and-installed options are only available on selected eligible products and locations

Hot water systems involve plumbing, gas, electrical work, pressure, valves, drainage and compliance. Use licensed trades where required.

Choosing the Right Hot Water System Before Installation

The best hot water system install starts with choosing the right system for the home. A unit that is too small may run out of hot water. A unit that is too large may cost more than needed. A unit with the wrong gas type, poor airflow or unsuitable electrical requirements can create installation problems.

Before choosing a system, consider:

Number of people in the home
Number of bathrooms
Shower length
Bath use
Kitchen and laundry use
Morning and evening peak demand
Existing system type
Existing system size
Whether the old system ran out of hot water
Electric, natural gas or LPG availability
Water pressure
Gas pipe sizing where relevant
Installation location
Access for delivery
Access for future servicing
Drainage and overflow
Electrical requirements
Rebate or STC eligibility where relevant

Do not choose a system based on product price alone. The right install depends on the product and the site.

Main Hot Water System Types to Install

The main hot water system types are:

Electric storage hot water
Gas storage hot water
Instant gas hot water
Heat pump hot water
Solar hot water
Instant electric hot water

Each system has different installation requirements.

Electric Hot Water System Install

Electric hot water systems are common in Australian homes and are often chosen for like-for-like replacements.

Electric storage systems use an electric element to heat water inside a tank. They may suit homes without gas, rental properties, simple replacements and households wanting a familiar storage-style system.

Electric hot water installation checks include:

Correct tank size
Existing electrical supply
Element size
Indoor or outdoor model suitability
Access for delivery
Base or slab condition
Valve requirements
Drainage and overflow
Tempering valve requirements
Pressure limiting valve requirements
Expansion control valve requirements
Old unit removal and disposal
Compliance upgrades

Common electric storage categories include:

Popular electric storage options include:

If the old electric system regularly ran out of hot water, replacing it with the same size may repeat the problem. Confirm sizing before ordering.

Gas Hot Water System Install

Gas hot water systems can suit homes already using natural gas or LPG. Gas systems may be gas storage or instant gas.

Gas hot water installation checks include:

Natural gas or LPG supply
Correct gas model
Gas pipe sizing
Water pressure
Outdoor or internal-flued suitability
Required clearances
Ventilation and flue requirements where applicable
Electrical connection for ignition or controls
Existing valves
Drainage and overflow
Access for installation and servicing
Compliance requirements

Gas work must be completed by a licensed gas fitter. Natural gas and LPG systems are not interchangeable.

Gas Storage Hot Water Install

Gas storage systems heat and store water in a tank. They can suit homes already using gas that want a storage-style replacement.

Common gas storage categories include:

Popular gas storage options include:

Gas storage may be practical where the old system worked well and the installation location is still suitable.

Instant Gas Hot Water Install

Instant gas hot water systems, also called continuous flow gas hot water systems, heat water as it flows through the unit.

Instant gas installation checks include:

Flow rate
Natural gas or LPG model
Gas pipe sizing
Water pressure
Outdoor wall location
Clearances around windows, doors and openings
Electrical requirements for ignition or controls
Temperature controller options
Existing system type
Whether pipework changes are required
Access for future servicing

Common instant gas sizes include 16L, 20L and 26L.

A 26L instant gas hot water system may suit some higher-demand homes, but it needs suitable gas pipe sizing and water pressure.

Popular instant gas options include:

External gas hot water units are outdoor units unless the specific manufacturer model is approved for internal flued installation.

Heat Pump Hot Water Install

A heat pump hot water system uses heat from the surrounding air to help heat stored water. Heat pumps are often compared by households replacing older electric storage systems or wanting a more energy-focused electric hot water option.

Heat pump installation checks include:

Outdoor location
Clear airflow
Manufacturer clearances
Condensate drainage
Electrical requirements
Base or slab condition
Access for delivery
Access for servicing
Noise placement
Distance from bedrooms and neighbouring windows
Existing system type
Existing valve condition
Old unit removal and disposal
Rebate or STC eligibility where relevant

Heat pumps should not be boxed into tight enclosed spaces. Poor airflow can reduce performance.

Many households compare:

Popular heat pump options include:

Solar Hot Water Install

Solar hot water systems use roof-mounted collectors to capture heat from the sun and transfer it into stored water. Most solar systems include an electric or gas booster for cloudy weather or high-demand periods.

Solar hot water installation checks include:

Roof orientation
Roof pitch
Shading
Collector placement
Roof access
Booster type
Tank location
Pipework route
Existing system type
Old collector removal where relevant
Electrical or gas requirements
Rebate or incentive eligibility where relevant

Solar can suit homes with good roof conditions, but it is not always the simplest replacement. For some homes, heat pump hot water may be easier to compare because it does not require roof-mounted collectors.

Instant Electric Hot Water Install

Instant electric hot water systems heat water on demand using electric heating elements.

They may suit:

Small sinks
Offices
Kitchenettes
Granny flats
Low-demand fixtures
Point-of-use hot water
Space-limited applications

Instant electric installation checks include:

Electrical capacity
Circuit requirements
Switchboard suitability
Flow rate
Intended fixture use
Plumbing location
Water pressure
Whether a dedicated circuit is required
Whether a licensed electrician is needed

Instant electric hot water is not always suitable for whole-home shower demand. Electrical requirements can be high, so installer confirmation is important before ordering.

Like-for-Like Replacement vs System Change

A hot water system install is usually simpler when replacing like-for-like, but that does not mean every like-for-like replacement is automatically the best choice.

Like-for-Like Replacement

This may involve replacing:

Electric storage with electric storage
Gas storage with gas storage
Instant gas with instant gas
Heat pump with heat pump

Like-for-like may be practical when the old system worked well, the household’s needs have not changed and the existing location remains suitable.

System Change

This may involve changing:

Electric storage to heat pump
Gas storage to instant gas
Electric storage to gas
Solar hot water to heat pump
Storage hot water to instant hot water
Indoor system to outdoor system

System changes can involve extra plumbing, electrical, gas, drainage, access or compliance work. Always confirm with licensed trades before ordering.

What Can Add Cost to a Hot Water System Install?

Installation costs can vary because every property is different.

Common cost factors include:

System type
New system size
Existing system type
Like-for-like replacement vs relocation
Indoor vs outdoor location
Tight access
Stairs or difficult delivery path
Existing valve condition
Tempering valve requirements
Pressure limiting valve requirements
Expansion control valve requirements
Drainage and overflow points
Electrical supply
Gas pipe sizing
Water pressure
Pipework route
Condensate drainage for heat pumps
Roof access for solar
Old unit removal
Disposal
Non-compliant existing installation
Base or slab condition

This is why a product-only price should not be treated as a complete installed price.

What Is Not Included in Supply-Only Hot Water Pricing?

For supply-only products, the listed product price generally covers the product only.

It does not usually include:

Installation labour
Plumbing alterations
Electrical work
Gas work
New valves
Pipework changes
Gas pipe upgrades
Drainage changes
Condensate drainage for heat pumps
Tempering valve upgrades
Pressure limiting valve upgrades
Expansion control valves
Old unit removal
Disposal
Compliance upgrades
Concrete bases or slab work
Flue kits unless listed
Temperature controllers unless listed
Relocation of the system
Rebate administration
Site assessment

Always check the product page and confirm full site requirements with your licensed installer before ordering supply only.

Supply-Only vs Supplied-and-Installed Hot Water Systems

Installed Today offers supply-only ordering across major Australian metro areas. This can suit customers who already have a licensed installer organised and want to order the product online.

Supply-only may suit you if:

Your installer has confirmed the correct product
The system size suits your household
The correct gas type has been selected where relevant
Electrical requirements have been checked
Water pressure has been reviewed
Access and drainage are suitable
You understand what is not included in the product price

Selected supplied-and-installed options are available on eligible products in Brisbane and Gold Coast service areas. Availability depends on the product, address and installation requirements.

Before choosing a supplied-and-installed option, check:

Whether the product is eligible
Whether your address is eligible
Whether the installation is like-for-like
Whether valves are included or extra
Whether electrical work is included or extra
Whether gas work is included or extra
Whether old unit removal is included
Whether disposal is included
Whether pipework changes are included
Whether drainage changes are included
Whether compliance upgrades may be extra
Whether rebates or STCs are included, excluded or handled separately

Do not assume every product or every location has an installed option.

Can You Install a Hot Water System Yourself?

No. A hot water system install can involve plumbing, gas fitting, electrical work, water pressure, valves, drainage and compliance requirements.

DIY installation can create serious risks, including:

Water leaks
Electrical hazards
Gas leaks
Incorrect temperature control
Non-compliant installation
Poor performance
Voided warranty
Damage to property
Unsafe hot water delivery
Insurance or compliance issues

Use licensed trades where required. Gas work must be completed by a licensed gas fitter. Electrical work must be completed by a licensed electrician where required. Plumbing work should be completed by a licensed plumber where required.

Professional Hot Water Installation Checks

A licensed installer may check:

Existing system type and size
New system suitability
Correct gas type where relevant
Water pressure
Electrical requirements
Gas pipe sizing
Existing valves
Drainage and overflow
Safe tray requirements where relevant
Tempering valve requirements
Access
Base or mounting requirements
Manufacturer clearances
Heat pump airflow and condensate drainage
Solar roof suitability
Old unit removal and disposal requirements
Compliance upgrades

The goal is not just to make the system fit. The goal is to make sure it can operate safely, reliably and legally.

Brisbane and Gold Coast Hot Water System Install Considerations

For Brisbane and Gold Coast homes, hot water system installs often depend on the existing unit, access, drainage, energy source and installation pathway.

Common local considerations include:

Replacing older electric storage systems
Comparing electric storage with heat pump upgrades
Natural gas vs LPG availability
Outdoor wall space for instant gas
Gas pipe sizing for 26L systems
Heat pump airflow and noise placement
Condensate drainage
Tight side access
Existing valve condition
Old unit removal and disposal
Whether the selected product is eligible for supplied-and-installed options

Installed Today offers selected supplied-and-installed options on eligible products in Brisbane and Gold Coast service areas, with supply-only ordering available across major Australian metro areas.

Rebates, STCs and Incentives

Some hot water systems, especially heat pumps and solar-style upgrades, may be eligible for rebates, STCs or other incentives depending on the product, location, supplier pathway and current program rules.

These incentives can change.

Before relying on a rebate or discount, confirm:

Whether the selected product qualifies
Whether your property qualifies
Whether the old system type matters
Whether supply-only purchases are eligible
Whether an approved provider or installer is required
Whether pre-approval is needed
Whether the incentive is applied upfront or claimed later
Whether the rebate or STC value is already included in the price

A rebate can improve value, but the system still needs to suit the home.

Maintenance After Installation

After a hot water system install, ongoing maintenance helps the system perform safely and reliably.

General maintenance considerations include:

Keeping the area around the unit clear
Checking for visible leaks
Watching for rust or corrosion
Monitoring hot water temperature
Checking for unusual noises
Keeping heat pump airflow clear
Checking heat pump condensate drainage
Checking valves where required
Following manufacturer servicing guidance
Using a licensed gas fitter for gas faults
Using a licensed electrician for electrical faults

Do not attempt plumbing, gas or electrical repairs yourself.

Common Installation Mistakes to Avoid

Choosing the Wrong Size

A system that is too small may run out of hot water. A system that is too large may cost more than needed.

Replacing Like-for-Like Without Checking Demand

If the old system struggled, the same size may repeat the problem.

Ordering the Wrong Gas Type

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

Choosing 26L Instant Gas Without Checking the Site

A 26L instant gas system needs suitable gas pipe sizing and water pressure.

Choosing Heat Pump Without Checking Location

Heat pumps need airflow, condensate drainage, access, electrical suitability and sensible noise placement.

Comparing Product-Only and Installed Pricing Incorrectly

Supply-only pricing is not the same as installed pricing.

Ignoring Valves and Drainage

Valves, overflow points and drainage can affect installation cost and compliance.

Attempting DIY Installation

Hot water systems require licensed trades where plumbing, gas or electrical work is involved.

Before Ordering Checklist

Before ordering a hot water system, confirm:

Current system type
Current system size
Whether the old system ran out of hot water
Number of people in the home
Number of bathrooms
Shower habits
Peak hot water demand
Electric, natural gas or LPG availability
Correct gas type where relevant
Electrical requirements
Gas pipe sizing for instant gas
Water pressure
Heat pump airflow and drainage
Solar roof suitability where relevant
Outdoor or indoor suitability
Access for delivery and installation
Drainage and overflow requirements
Whether new valves may be needed
Whether old unit removal is included
Whether disposal is included
Whether rebates or STCs may apply
Whether supply-only affects rebate eligibility
Whether supply-only or supplied-and-installed is the right option
Installer confirmation before buying supply only

Frequently Asked Questions

What is involved in a hot water system install?

A hot water system install may involve removing the old system, positioning the new unit, connecting water pipework, checking valves, connecting electrical or gas services where required, managing drainage and testing the system for safe operation.

Can I install a hot water system myself?

No. Hot water systems involve plumbing, gas, electrical work, water pressure, valves, drainage and compliance requirements. Use licensed trades where required.

Does supply-only hot water pricing include installation?

No. Supply-only generally means the product only unless installation is selected or clearly shown. Installation, valves, electrical work, gas work, pipework, drainage, removal, disposal and compliance upgrades are usually separate.

What is the easiest hot water system to install?

A like-for-like replacement is often simpler than changing system type, but the existing location, valves, access, drainage and compliance still need to be checked.

What adds cost to a hot water system install?

Common cost factors include access, old valves, electrical work, gas pipe sizing, drainage, pipework changes, relocation, old unit removal, disposal and compliance upgrades.

Can I replace electric storage with a heat pump?

Yes, in some homes. A heat pump needs suitable outdoor space, airflow, condensate drainage, electrical suitability, access and sensible noise placement.

Can I replace gas storage with instant gas?

Yes, in some homes. Gas pipe sizing, water pressure, outdoor wall location, clearances and correct gas type must be checked first.

Do heat pumps need special installation?

Heat pumps need clear airflow, condensate drainage, electrical suitability, access, base support and suitable noise placement. They should not be installed in tight enclosed spaces.

Do instant gas hot water systems need electricity?

Some instant gas systems need electricity for ignition, controls or operation. Check the specific model before ordering.

Are hot water rebates available for installation?

Some heat pump and solar-style systems may be eligible for rebates, STCs or incentives depending on product, location and current program rules. Eligibility can change, so confirm before ordering.

Final Word

A hot water system install should start with the right product choice, not just the cheapest unit. Electric, gas, instant gas, heat pump, solar and instant electric systems all have different installation requirements and suitability checks.

Supply-only ordering can be a good option when you already have a licensed installer organised and the product has been confirmed as suitable. Selected supplied-and-installed options are available on eligible Installed Today products in Brisbane and Gold Coast service areas, but inclusions and eligibility should always be checked before ordering.

Before buying, confirm the system size, energy source, gas type, electrical requirements, water pressure, access, drainage, valves, removal, disposal and compliance requirements with your licensed installer.

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