Second Hand Hot Water System: Is Buying Used Worth the Risk?

Oct 8, 2024

Buying a second hand hot water system can look like an easy way to save money, but it can also create problems if the unit is old, damaged, inefficient, incorrectly sized or unsuitable for your property. A used system may be cheaper upfront, but the real cost can increase quickly once you include installation, valves, electrical work, gas work, compliance upgrades, removal, disposal and the risk of a shorter remaining lifespan.

For most homes, a new hot water system is usually the safer long-term choice. New systems give you clearer product history, manufacturer warranty, better model selection and fewer unknowns around corrosion, leaks, age and past maintenance.

Installed Today makes it easy to compare and order new hot water systems online, with supply-only ordering available across major Australian metro areas and selected supplied-and-installed options available on eligible products in Brisbane and Gold Coast service areas.

Quick Answer: Should You Buy a Second Hand Hot Water System?

A second hand hot water system is usually not recommended unless it has been properly inspected, has clear service history, is still in good condition, suits your property and can be installed safely by licensed trades.

The main risks include:

Hidden tank corrosion
Leaks that are not visible at pickup
No or limited warranty
Unknown service history
Short remaining lifespan
Higher running costs
Incorrect size for your household
Wrong gas type
Missing valves or parts
Non-compliant installation requirements
Extra removal, disposal or modification costs
Possible damage during transport

A cheap used unit may become expensive if it fails early or needs major installation work. Before buying second hand, compare new options such as electric hot water systems, gas hot water systems, instant gas hot water systems and heat pump hot water systems.

Why People Consider Second Hand Hot Water Systems

Most people look at used hot water systems for one reason: upfront price.

A second hand system may seem attractive if:

Your old system has failed unexpectedly
You are trying to reduce replacement cost
You are replacing a system in a rental or temporary property
You found a cheap unit online
A neighbour or tradesperson is removing a working unit
You only need a short-term solution

The problem is that hot water systems are not simple plug-in appliances. They involve plumbing, water pressure, electrical work, gas work, valves, drainage and compliance requirements. Even if the unit itself is cheap, making it safe and suitable for your home may not be.

The Main Risks of Buying a Used Hot Water System

Hidden Tank Corrosion

Storage hot water tanks can corrode from the inside. A used tank may look clean externally but still be close to failure inside.

Warning signs may include:

Rust marks
Discoloured water stains
Corrosion around fittings
Bulging or damaged casing
Old valves
Dampness around the base
Previous patching or repairs

A leaking storage tank usually means replacement, not repair. If a second hand tank fails shortly after installation, you may end up paying twice.

Unknown Age

Age is one of the biggest issues with second hand hot water systems. If the seller does not know the manufacture date or installation date, you may be buying a system with limited life left.

Before buying, check:

Compliance plate
Serial number
Manufacture date
Model number
Installation date if known
Warranty status
Any visible date markings
Service records

A cheap used system that is already near the end of its expected life may not be good value.

No Clear Warranty

Many second hand hot water systems do not come with a transferable warranty. Even if the system is still within a manufacturer warranty period, the warranty may depend on installation history, service records, proof of purchase and approved use.

Before buying, check whether:

The warranty is still active
The warranty transfers to a second owner
Proof of original purchase is available
The system has been serviced as required
The model has been installed according to manufacturer instructions
The system has been modified or relocated before

A new system is usually a cleaner option if warranty support matters.

Damage During Removal or Transport

Hot water systems can be damaged when disconnected, moved or stored. A tank or heat pump may have been working before removal but become damaged during transport.

Possible issues include:

Bent pipe connections
Damaged casing
Cracked fittings
Broken sensors
Damaged heat pump components
Dented tanks
Water left inside during storage
Electrical damage
Gas component damage

A system sitting outdoors, in a shed or on a trailer may have been exposed to weather or rough handling.

Higher Running Costs

Older systems are often less efficient than newer models. Even if they still heat water, they may cost more to run.

This matters if you are comparing a used electric storage unit against new options such as heat pump hot water systems or newer electric storage systems.

A second hand system may save money upfront but cost more over time through energy use, repairs and early replacement.

Incorrect Size for Your Home

A used hot water system may be cheap because it is available, not because it is right for your household.

A system that is too small may run out of hot water. A system that is too large may cost more than needed and may not suit the location.

Before buying any hot water system, new or used, consider:

Number of people in the home
Number of bathrooms
Shower habits
Bath use
Kitchen and laundry use
Peak morning and evening demand
Current system size
Whether the old system ran out of hot water
Available energy source
Installation space

For electric storage, many homes compare 250L electric hot water systems, 315L electric hot water systems and 400L electric hot water systems.

Used Electric Hot Water Systems

A second hand electric storage system may seem simple, especially if your old unit was also electric. However, it still needs to suit the home’s electrical supply, plumbing, valves, drainage and installation position.

Risks with used electric systems include:

Old or worn heating elements
Faulty thermostat
Internal tank corrosion
Sediment buildup
Incorrect tank size
High running costs
No warranty
Damaged electrical connections
Old valves needing replacement
Compliance upgrades during installation

If you want a straightforward electric replacement, compare new electric hot water systems instead. Popular new options include the Rheem 250L Electric Hot Water System, Rinnai 250L Electric Hot Water System, Dux 250L Electric Hot Water System and Vulcan 250L Electric Hot Water System.

Used Gas Hot Water Systems

Second hand gas hot water systems carry extra risk because the gas type, condition and installation requirements must be correct.

Gas systems may use natural gas or LPG. These are not interchangeable.

Before even considering a used gas hot water system, confirm:

Whether it is natural gas or LPG
Whether your property uses the same gas type
Whether the unit has been converted before
Whether the model is approved for the intended installation
Whether the gas pipe sizing is suitable
Whether the flue or outdoor location requirements can be met
Whether a licensed gas fitter is willing to install it

Gas work must be completed by a licensed gas fitter.

For a cleaner buying path, compare new gas hot water systems, 130/135L gas hot water systems, 160/170L gas hot water systems and instant gas hot water systems.

Used Instant Gas Hot Water Systems

Instant gas hot water systems, also called continuous flow systems, can be risky to buy second hand if the condition and gas type are unclear.

Potential issues include:

Wrong gas type
Damaged heat exchanger
Old sensors
Faulty ignition
Scale buildup
Water flow problems
Unknown service history
Missing temperature controllers
Damaged casing
Faulty gas valves
No warranty

A 26L second hand instant gas unit may look like a bargain, but it still needs suitable gas pipe sizing and water pressure. If the property cannot support the unit, it may not perform properly.

If you want continuous flow hot water, compare new 26L instant gas hot water systems, including natural gas and LPG options such as the Rinnai Infinity B26 Natural Gas Hot Water System, Rinnai Infinity B26 LPG Gas Hot Water System, Rheem 26L Natural Gas Hot Water System and Rheem 26L LPG Gas Hot Water System.

Used Heat Pump Hot Water Systems

A used heat pump hot water system may seem appealing because new heat pumps usually cost more upfront than standard electric storage systems. However, heat pumps have more components than a basic storage tank.

Risks with used heat pumps include:

Compressor wear
Fan issues
Sensor faults
Refrigerant circuit concerns
Damaged casing
Unknown operating history
Poor storage or transport damage
Tank corrosion
No warranty
Noise issues
Incomplete parts
Incompatibility with rebate pathways

Heat pumps also need the right installation environment. They require outdoor space, clear airflow, condensate drainage, access, suitable electrical supply and sensible noise placement.

Before buying used, compare new heat pump hot water systems, medium heat pump hot water systems 200L–280L, large heat pump hot water systems and Wi-Fi enabled heat pump hot water systems.

Used Solar Hot Water Systems

Second hand solar hot water systems can be complex because the tank, collectors, pump, sensors, booster and roof hardware all need to be suitable and complete.

Possible problems include:

Damaged collectors
Old or leaking tank
Failed pump
Faulty sensors
Missing roof mounting parts
Incorrect booster setup
Poor frost suitability in some regions
No warranty
Difficult installation
Compatibility issues with your roof and household demand

Solar hot water may be efficient in the right home, but buying used can make the setup harder to verify. In some homes, a new heat pump may be easier to compare than a second hand solar hot water system.

Questions to Ask Before Buying a Second Hand Hot Water System

Before buying a used hot water system, ask the seller:

Why is it being removed?
How old is the system?
What is the model number?
What is the serial number?
Is proof of purchase available?
Is the warranty still valid?
Is the warranty transferable?
Has the system ever leaked?
Has it been repaired?
Has it been serviced regularly?
Was it installed indoors or outdoors?
Was it exposed to weather after removal?
Has it been transported upright?
Are all parts included?
Is it natural gas or LPG?
Has the gas type been converted?
Was the unit working immediately before removal?
Why was it replaced?

If the seller cannot answer basic questions, treat the purchase as high risk.

What to Inspect Before Buying Used

A used hot water system should be inspected carefully before purchase.

Check for:

Rust
Corrosion around fittings
Dents
Cracks
Leaks
Water staining
Missing parts
Damaged valves
Damaged electrical connections
Damaged gas connections
Signs of overheating
Previous repairs
Scale buildup
Old compliance plate
Scratches or transport damage

A licensed plumber, gas fitter or electrician should confirm suitability before installation. Do not rely only on the seller’s description.

Why a Professional Inspection Matters

A second hand hot water system may have problems that are not obvious from photos.

A licensed installer can help identify:

Whether the unit is suitable for the property
Whether the unit is safe to install
Whether the size is correct
Whether the gas type is correct
Whether electrical requirements suit the home
Whether valves and drainage need upgrading
Whether the unit appears damaged
Whether installation will cost more than expected

A professional check can prevent buying a system that cannot legally, safely or practically be installed.

Second Hand vs New Hot Water Systems

Option	Upfront Cost	Risk Level	Warranty	Best Suited To
Second hand hot water system	Lower upfront	Higher	Often limited or none	Temporary situations only, after professional inspection
New electric storage	Usually affordable upfront	Lower	Clearer manufacturer warranty	Simple replacements and homes without gas
New gas hot water	Moderate	Lower	Clearer manufacturer warranty	Homes with suitable natural gas or LPG
New instant gas	Moderate	Lower	Clearer manufacturer warranty	Continuous flow gas hot water
New heat pump	Higher upfront	Lower	Clearer manufacturer warranty	Energy-focused homes with suitable outdoor space

A used hot water system may save money at purchase, but a new system usually gives better confidence around age, condition, warranty and suitability.

When a Second Hand Hot Water System Might Be Considered

A second hand hot water system may only be worth considering if:

It is relatively new
It has clear proof of age
It has proof of purchase
It has service records
It has not been sitting outside for long
It has been removed carefully
It matches your energy source
It is the correct size
It passes inspection by a licensed installer
It has some transferable warranty or clear support
The installation cost still makes the total price worthwhile

Even then, compare the full cost against buying new before deciding.

Why a New Hot Water System Is Usually Better Value

A new hot water system usually offers:

Clear product history
Manufacturer warranty
Known model and specifications
Better energy efficiency options
Correct gas type selection
Correct size selection
Fewer hidden damage risks
Better access to parts and support
Cleaner installer approval
Better rebate or STC eligibility where applicable
Longer expected service life

For most households, these benefits outweigh the small upfront saving of buying second hand.

Affordable New Hot Water Alternatives

If you are looking at second hand because of price, compare affordable new options first.

Electric Storage

Electric storage is often one of the more affordable upfront options. Compare 250L electric hot water systems, 315L electric hot water systems and 400L electric hot water systems.

Gas Storage

If your home already has gas, compare 130/135L gas hot water systems, 160/170L gas hot water systems and 5-star gas hot water systems.

Instant Gas

If you want continuous flow hot water, compare instant gas hot water systems in the correct natural gas or LPG version.

Heat Pump

If long-term energy use matters, compare heat pump hot water systems, especially if rebates, STCs or incentives may apply.

Rebates and incentives can change, so check current eligibility before relying on them in your budget.

What Is Not Included in Supply-Only Pricing?

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

It does not usually include:

Installation labour
New valves
Electrical work
Gas work
Pipework changes
Drainage changes
Tempering valve upgrades
Pressure limiting valve upgrades
Expansion control valves
Condensate drainage for heat pumps
Old unit removal
Disposal
Compliance upgrades
Concrete bases or slab work
Relocation of the system

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

Supply-Only vs Supplied-and-Installed

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
You know the right size and model
The correct gas type has been selected
Electrical requirements have been checked
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, location and installation requirements.

Brisbane and Gold Coast Considerations

For Brisbane and Gold Coast homes, a second hand hot water system can be especially risky if the old system type, location, gas supply or drainage requirements do not match the property.

Common local checks include:

Natural gas vs LPG availability
Outdoor access
Side access
Drainage and overflow points
Existing valve condition
Electrical circuit suitability
Heat pump airflow and noise placement
Gas pipe sizing for instant gas
Water pressure
Whether the old system was undersized

If you are ordering supply only, confirm suitability with your licensed installer before buying any system.

Common Mistakes When Buying a Second Hand Hot Water System

Buying Only Because It Is Cheap

The cheapest unit can become expensive if it fails early or needs extra installation work.

Not Checking the Gas Type

Natural gas and LPG units are different. Ordering the wrong gas type can make the system unsuitable.

Ignoring Age

A used system near the end of its service life may not be worth installing.

Skipping Professional Inspection

A seller’s photos are not enough. Hidden corrosion or damaged components may not be visible.

Forgetting About Installation Costs

A cheap used system still needs proper installation, valves, pipework, drainage, electrical work or gas work where required.

Buying the Same Size Without Checking Demand

If your old system ran out of hot water, a second hand system of the same size may repeat the problem.

Assuming Warranty Applies

Second hand units may not have transferable warranty support.

Before Buying Checklist

Before buying a second hand hot water system, confirm:

System age
Model number
Serial number
Proof of purchase
Warranty status
Whether warranty is transferable
Service history
Reason for removal
Whether it was working before removal
Whether it has leaked
Whether it has visible corrosion
Correct gas type if applicable
Correct electrical requirements
Correct tank size or flow rate
Whether all parts are included
Whether transport caused damage
Whether your installer will install it
Whether the total cost still beats buying new

If any of these checks are uncertain, buying new is usually safer.

Frequently Asked Questions

Is it safe to buy a second hand hot water system?

It can be risky. Used hot water systems may have hidden corrosion, leaks, no warranty, unknown service history or suitability issues. A licensed installer should inspect the unit before installation.

Is a second hand hot water system worth it?

Usually only if it is relatively new, has clear service history, suits your property and passes professional inspection. In many cases, a new system is better value long term.

Can I install a used hot water system myself?

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

How old is too old for a used hot water system?

There is no single age limit, but older systems carry more risk. Check the manufacture date, condition, service history and warranty before considering purchase.

Can I buy a second hand gas hot water system?

You can, but it must be the correct natural gas or LPG model and must be installed by a licensed gas fitter. Gas pipe sizing, water pressure and safety requirements must be checked.

Are second hand heat pump hot water systems a good idea?

They can be risky because heat pumps include compressors, fans, sensors and other components that may be expensive to repair. Check warranty, age, transport history and site suitability carefully.

Is it better to buy a new electric hot water system?

For many homes, yes. A new electric storage system gives clearer warranty, known condition and easier installer approval. It can also avoid the hidden risks of a used tank.

What is the cheapest new hot water system?

Electric storage is often one of the cheaper upfront options, but running costs depend on tariff, usage and system size. Gas and heat pump options may be better value for some homes.

What is not included in supply-only hot water system pricing?

Supply-only pricing generally excludes installation, valves, electrical work, gas work, pipework changes, drainage, old unit removal, disposal and compliance upgrades unless selected or clearly shown.

Final Word

A second hand hot water system can look like a bargain, but the risks are real. Hidden corrosion, no warranty, incorrect sizing, wrong gas type, transport damage and installation extras can turn a cheap unit into an expensive mistake.

For most homes, a new hot water system is the safer long-term choice. You get clearer product history, warranty support, better model selection and fewer unknowns.

Before buying used, get professional advice and compare the total cost against a new electric, gas, instant gas or heat pump system. The best hot water system is not the cheapest one on the day. It is the one that safely suits your home, household demand and long-term budget.

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