No Hot Water? What to Check Before Replacing Your Hot Water System

Feb 16, 2024

hot water is one of the most frustrating household problems, especially when it happens before work, after sport, during a family morning routine or when guests are staying. The cause can be simple, such as a tripped circuit breaker, gas supply issue or an empty storage tank after heavy use. It can also point to a failing hot water system that needs professional inspection or replacement.

The safest first step is to identify what type of hot water system you have and look for obvious signs of trouble without opening, repairing or modifying the unit yourself. Electric, gas, instant gas, heat pump and storage systems can all fail in different ways.

If your system is leaking, tripping power, showing error codes, smelling of gas, running cold repeatedly or struggling to keep up with normal household use, it may be time to compare replacement options.

You can compare Hot Water Systems, Electric Hot Water Systems, Gas Hot Water Systems, Instant Gas Hot Water Systems, Instant Electric Systems and Heat Pump Hot Water Systems online with Installed Today.

Quick answer: what should you do if you have no hot water?

If you have no hot water, start with safe checks only:

Check whether the system is electric, gas, instant gas, heat pump or solar boosted
Check whether the power is on
Check whether the circuit breaker has tripped
Check whether gas supply is available if it is a gas system
Check whether the system is leaking
Check whether an error code is showing
Check whether the household simply used all stored hot water
Check whether the issue happens at every tap or only one outlet
Stop using the system if there is a gas smell, electrical fault, major leak or burning smell
Call the right licensed professional if the issue is not obvious or safe to resolve

Do not remove covers, touch wiring, repair gas parts, relight a system where a gas leak is suspected, replace elements, adjust internal controls or open the unit yourself.

First: work out what type of hot water system you have

The cause of no hot water depends heavily on the system type.

Common hot water system types include:

Electric storage
Gas storage
Instant gas
Instant electric
Heat pump
Solar hot water with electric or gas boost

Each system has different failure points, safety risks and replacement options.

Electric storage hot water: common no hot water causes

An electric storage hot water system heats water in a tank using one or more electric elements.

Common reasons for no hot water may include:

Tripped circuit breaker
Failed heating element
Faulty thermostat
Failed boost or controlled-load supply
Undersized tank
Heavy household use
Faulty tempering valve
Leaking cylinder
Electrical fault
Old system nearing end of life

Safe checks include:

Check whether the circuit breaker has tripped
Check whether other electrical appliances are working
Check whether the issue started after heavy hot water use
Look for visible leaking around the tank
Listen for unusual noises
Check whether hot water returns after a full heating cycle

Do not remove electrical covers or attempt element or thermostat repairs. Electric hot water faults should be handled by the right licensed professional.

If the system is old, leaking or regularly running out, compare Electric Hot Water Systems.

Gas storage hot water: common no hot water causes

A gas storage hot water system stores hot water in a tank and reheats it using gas.

Common reasons for no hot water may include:

Gas supply issue
Pilot light problem
Burner fault
Thermocouple issue
Gas valve issue
Faulty thermostat
Leaking tank
Failed relief valve
Heavy demand emptying the tank
Incorrect gas type after replacement
Old system failure

Safe checks include:

Check whether other gas appliances are working
Check whether the system is visibly leaking
Check whether the issue follows heavy hot water use
Check whether the system has gone out repeatedly
Check for error labels or visible status indicators if fitted

If you smell gas, hear hissing or suspect a gas leak, do not try to relight the system. Turn off the gas supply if safe, move away from the area and contact the appropriate gas emergency service or a licensed gas fitter.

Compare Gas Hot Water Systems if your gas storage unit is old, leaking or unreliable.

Instant gas hot water: common no hot water causes

Instant gas hot water systems heat water as it flows through the unit. They do not store hot water in a tank.

Common reasons for no hot water may include:

No gas supply
No electrical power to the unit
Low water flow
Low water pressure
Error code
Blocked filter
Ignition issue
Gas valve fault
Incorrect gas type
Undersized gas pipework
Faulty controller
Internal component failure

Safe checks include:

Check whether power is available to the unit
Check whether other gas appliances are working
Check whether the issue happens at all hot taps
Check for an error code
Check whether water flow is very low
Check whether the unit starts and then shuts down
Check whether hot water works at one tap but not another

Do not open the unit, repair gas parts, adjust internal gas settings or bypass safety controls.

If your instant gas system is old, undersized or frequently showing error codes, compare Instant Gas Hot Water Systems.

Heat pump hot water: common no hot water causes

A heat pump hot water system uses electricity to draw heat from the surrounding air and transfer it into stored water.

Common reasons for no hot water may include:

Power supply issue
Timer setting issue
Boost mode not operating as expected
Fault code
Poor airflow
Blocked air intake
Condensate drainage issue
Compressor or fan fault
Backup element issue
Undersized system
Heavy household use
Cold weather recovery delay
Old system failure

Safe checks include:

Check whether power is on
Check whether the unit shows an error code
Check whether the timer settings have changed
Check whether the outdoor area around the unit is blocked
Check whether the system has enough airflow
Check whether the household used more hot water than normal
Check whether the issue happens after peak demand periods

Do not open electrical panels or attempt refrigeration repairs.

If your old electric storage system has failed and you are considering a more efficient electric upgrade, compare Heat Pump Hot Water Systems.

Instant electric hot water: common no hot water causes

Instant electric hot water systems heat water on demand using electricity.

Common reasons for no hot water may include:

Electrical supply issue
Tripped breaker
Flow rate too low
Unit undersized for the outlet
Electrical fault
Temperature setting issue
Internal component failure
Water pressure issue

Instant electric systems can have significant electrical requirements. Do not open the unit or attempt internal repairs.

Compare Instant Electric Systems if you need a compact electric option for a suitable application.

Is it no hot water everywhere or just one tap?

This is one of the most useful checks.

If there is no hot water anywhere, the issue is more likely to involve the hot water system, power supply, gas supply, storage tank, heat source or major valve.

If only one tap or shower has no hot water, the issue may be local to that fixture.

Possible one-outlet issues include:

Faulty mixer tap
Shower cartridge issue
Blocked outlet
Tempering valve issue
Plumbing crossover
Localised pipework issue
Low flow at that fixture

If other taps have hot water, the system itself may not be the problem.

Is the water cold or only lukewarm?

Cold water and lukewarm water can point to different issues.

Cold water may suggest:

No power
No gas
Failed element
Ignition failure
System fault
Empty storage tank after heavy use
Major component failure

Lukewarm water may suggest:

Thermostat issue
Tempering valve problem
Undersized system
Heavy use
Failed lower element in some electric tanks
Gas burner issue
Heat pump recovery issue
Mixer tap problem
Plumbing crossover

Lukewarm water can also happen when the system is partly working but not heating properly.

Has the hot water run out after heavy use?

Sometimes the system is not broken. It may simply be undersized or temporarily depleted.

This can happen after:

Multiple long showers
Back-to-back family showers
Bath filling
Guests staying
Laundry use
Dishwasher use
Airbnb turnover
Morning and evening peak demand
Off-peak electric tank heating delay

If hot water returns later, the issue may be sizing, usage or recovery time.

If this happens regularly, the system may be too small for the household.

Compare larger Electric Hot Water Systems, Gas Hot Water Systems, Instant Gas Hot Water Systems or Heat Pump Hot Water Systems depending on your energy source and site.

Check the power supply safely

For electric storage, heat pump and many instant gas systems, power matters.

Safe checks include:

Check whether the circuit breaker has tripped
Check whether nearby power points are working
Check whether the hot water isolator is on
Check whether there has been a power outage
Check whether the system display is blank
Check whether a timer or controlled-load supply is involved

If a breaker trips repeatedly, do not keep resetting it. Repeated tripping may indicate an electrical fault that needs a licensed electrician or suitable professional.

Check gas supply safely

For gas storage and instant gas systems, gas supply is critical.

Safe checks include:

Check whether other gas appliances are working
Check whether LPG bottles are empty if the property uses LPG
Check whether the gas meter is on if safe and accessible
Check for error codes
Check whether the system starts and then stops

Stop immediately if you smell gas, hear hissing, feel unwell near the unit or suspect a leak.

Natural gas and LPG are not interchangeable. If you have recently replaced or moved into a property, confirm the system matches the property’s gas type.

Check for visible leaks

A leaking hot water system can quickly become a replacement issue.

Look for:

Water pooling around the base
Rust-coloured stains
Water dripping from the tank
Water from pipe connections
Relief valve discharge
Wet insulation
Corrosion around fittings
Water marks on walls or floor
Steam or unusual discharge

A small amount of discharge from a relief valve can occur at times, but constant leaking should be checked.

If the cylinder itself is leaking, replacement is often required.

Check for error codes

Modern hot water systems may show error codes on the unit or controller.

Error codes can appear on:

Instant gas units
Heat pumps
Some electric systems
Solar-boosted systems
Temperature controllers

Do not ignore repeated error codes. They can point to ignition, flow, temperature, fan, sensor, gas, electrical or internal faults.

Record the code and provide it to the licensed professional or supplier.

Check whether the system is old

Age matters.

A hot water system may become less reliable as parts wear, tanks corrode, valves age and efficiency drops.

Replacement may be worth considering if the system is:

Old and unreliable
Leaking from the tank
Requiring repeated repairs
Running out of hot water often
Showing frequent error codes
Rusty or corroded
Too small for the household
Expensive to run
No longer suited to the home

At some point, repeated repairs can cost more than planning a proper replacement.

No hot water from an electric storage system

If an electric storage system has no hot water, possible causes include:

Tripped breaker
Failed element
Faulty thermostat
Controlled-load timing issue
Wiring fault
Failed safety control
Undersized tank
Heavy household use
Leaking tank

If the system is still structurally sound, a licensed professional may diagnose whether repair is possible.

If the tank is leaking, very old or regularly running out, replacement is usually worth comparing.

No hot water from a gas storage system

If a gas storage system has no hot water, possible causes include:

Pilot light problem
Gas supply issue
Burner fault
Thermocouple fault
Gas control issue
Faulty thermostat
Tank leak
Heavy demand
Incorrect gas type
Age-related failure

Gas work should only be handled by a licensed gas fitter.

If the system is leaking or has repeated gas-related faults, compare replacement options.

No hot water from an instant gas system

If an instant gas system is not producing hot water, possible causes include:

No power
No gas
Low water flow
Blocked inlet filter
Gas pressure problem
Ignition failure
Error code
Water pressure issue
Controller issue
Heat exchanger issue
Undersized gas pipework

Instant gas systems need correct gas, water and power conditions to operate properly.

If the system is old, undersized or repeatedly faulty, compare modern Instant Gas Hot Water Systems.

No hot water from a heat pump

If a heat pump has no hot water, possible causes include:

No power
Timer or schedule issue
Fault code
Poor airflow
Fan problem
Compressor issue
Backup element issue
Heavy use
Cold weather recovery delay
Condensate drainage issue
Electrical fault

Heat pumps need suitable outdoor airflow, drainage and electrical setup.

If an old electric storage system has failed, a heat pump may be worth comparing as an efficient electric upgrade.

Running out of hot water every day

If hot water runs out every day, the system may be undersized or not recovering properly.

Common causes include:

Tank too small
More people in the home than before
Longer showers
New bathroom
Higher-flow shower heads
Bath use
Off-peak tank not large enough
Failed lower element in some electric tanks
Heat pump timer not suited to usage
Instant gas flow rate too low
Gas or water supply issue

Do not assume the same replacement size is correct. If the old system could not keep up, choose the next system based on current household demand.

Hot water is too hot

Water that is too hot can be dangerous.

Possible causes include:

Thermostat issue
Tempering valve issue
Incorrect setting
Faulty control
Installation problem
System overheating

Do not adjust internal controls yourself. Scalding risk is serious, especially for children, elderly people and vulnerable users.

A licensed professional should check the system and tempering valve.

Hot water is not hot enough

Water that is not hot enough may be caused by:

Thermostat issue
Tempering valve problem
Heavy use
Undersized system
Failed element
Heat pump recovery issue
Gas burner issue
Mixer tap crossover
Incorrect controller setting
Old system performance decline

If the issue is new, diagnosis may be needed. If the issue has always happened, the system may be undersized or poorly suited to the household.

Hot water temperature fluctuates

Temperature fluctuations can happen with storage and instant systems.

Possible causes include:

Low water pressure
Flow rate changes
Multiple outlets running
Mixer tap issue
Tempering valve fault
Gas pressure issue
Instant gas unit undersized
Blocked filters
Scale build-up
Plumbing crossover
Controller issue

Temperature fluctuation should be diagnosed before replacing parts or choosing a new system.

Hot water smells unusual

Unusual hot water smells may indicate water quality, tank, anode, bacteria, drain or plumbing issues.

Possible signs include:

Rotten egg smell
Metallic smell
Musty smell
Chemical smell
Rusty or discoloured water

Do not ignore unusual smells, especially if they appear suddenly.

If the issue may be water-quality related, filtration or testing may be worth considering separately from hot water replacement.

Hot water looks rusty or brown

Rusty or brown hot water may come from:

Corroding tank
Pipework corrosion
Sediment
Water supply issue
Anode issues
Old system deterioration

If cold water is clear but hot water is discoloured, the hot water system or hot water pipework may be involved.

A leaking or corroded tank may need replacement.

The hot water system is making noise

Noises can indicate different issues depending on the system.

Possible noises include:

Rumbling
Popping
Hissing
Clicking
Whistling
Fan noise
Burner noise
Pump noise
Water hammer

Storage tanks may become noisy from sediment or heating issues. Heat pumps may have fan and compressor noise. Gas systems may have burner or ignition sounds.

New or unusual noise should be checked.

Should you repair or replace a hot water system?

Repair may make sense if:

The system is relatively new
The tank is not leaking
The fault is minor
Parts are available
Warranty may apply
The system is still correctly sized
Running costs are acceptable

Replacement may make sense if:

The tank is leaking
The system is old
Repairs are frequent
Parts are expensive or hard to get
The system is undersized
Running costs are high
You want to change energy source
The installation needs compliance upgrades
The system no longer suits the household

A leaking tank, serious corrosion or repeated breakdowns often make replacement the better long-term decision.

Choosing a replacement hot water system

If replacement is needed, compare system types carefully.

Main options include:

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

The best replacement depends on:

Existing system type
Energy source
Household size
Number of bathrooms
Shower habits
Bath use
Installation location
Access
Gas supply
Electrical supply
Water pressure
Drainage
Budget
Long-term running cost goals

Start with Hot Water Systems if you are comparing all replacement options.

Electric storage replacement

Electric storage may suit:

Homes already using electric storage
Units and townhouses
Homes without gas
Simple like-for-like replacement
Lower upfront budget
Off-peak or controlled-load setups where suitable

Before replacing electric storage, check:

Tank size
Whether the old tank ran out
Electrical supply
Installation location
Valves
Access
Drainage
Old unit removal
Disposal
Whether heat pump hot water may suit better

Compare Electric Hot Water Systems.

Gas hot water replacement

Gas hot water may suit:

Homes already connected to natural gas or LPG
Customers replacing gas storage
Homes replacing instant gas
Properties with suitable gas supply
Households wanting fast recovery or continuous flow

Before replacing gas hot water, check:

Natural gas or LPG
Gas pipe sizing
Water pressure
Installation location
Outdoor clearances
Power requirements for instant gas
Valves
Compliance
Old unit removal
Disposal

Compare Gas Hot Water Systems and Instant Gas Hot Water Systems.

Heat pump replacement

Heat pump hot water may suit:

Homes replacing electric storage
Customers wanting an efficient electric upgrade
Homes with rooftop solar where timer settings suit
Properties with suitable outdoor airflow
Properties with condensate drainage
Homes moving away from gas

Before choosing heat pump hot water, check:

Outdoor location
Airflow
Condensate drainage
Noise placement
Electrical supply
Tank size
Recovery time
Timer settings
Access
Old unit removal
Disposal
Compliance upgrades

Compare Heat Pump Hot Water Systems.

Hot water system sizing

Sizing is one of the biggest replacement decisions.

As a general guide:

Household	Systems commonly compared
1 person	Smaller electric storage, instant electric for suitable use, smaller gas where available
2 people	125L to 160L electric, smaller instant gas, compact heat pump where suitable
3 to 4 people	250L electric, 20L to 26L instant gas, suitable heat pump
5+ people	315L to 400L electric, larger gas storage, 26L instant gas or larger design, larger heat pump
High-demand home	Larger storage, confirmed instant gas sizing or heat pump design

This is only a guide. Shower habits, bath use, guest use and peak demand matter.

Supply-only hot water replacement

Supply-only ordering can suit customers who already have their own licensed installer arranged.

Supply only may suit:

Builders
Renovators
Landlords
Property managers
Trade customers
Homeowners managing their own installation
Customers outside supplied-and-installed service areas

Supply-only product pricing generally does not include installation, valves, old unit removal, disposal, electrical work, gas work, pipework changes, drainage, access upgrades or compliance upgrades unless clearly selected or included.

Before ordering supply only, your licensed installer should confirm the system suits the property.

Supplied-and-installed hot water replacement

Supplied-and-installed options may be available on selected products in eligible Brisbane and Gold Coast service areas where shown.

This can suit customers who want the product and installation pathway arranged together.

Before ordering supplied and installed, check:

Service area eligibility
Existing system type
Installation inclusions
Valve requirements
Electrical work
Gas work
Old unit removal
Disposal
Pipework changes
Drainage
Access
Base or slab condition
Compliance upgrades
Product suitability

Do not assume every possible site requirement is included. Check the selected product and installation options carefully.

Brands to compare if replacing your hot water system

Installed Today includes several homepage-linked hot water brands worth comparing:

Choose by system type, size and installation suitability, not brand alone.

Common mistake: resetting a breaker repeatedly

If the hot water circuit keeps tripping, stop resetting it.

Repeated tripping may indicate a fault that needs professional electrical diagnosis.

Common mistake: trying to repair gas parts yourself

Gas hot water repairs should only be handled by a licensed gas fitter.

Do not adjust burners, gas valves, pilot assemblies, thermocouples or internal gas components yourself.

Common mistake: ignoring leaks

A leaking hot water system can cause property damage and may indicate a failing tank or valve.

Do not ignore pooling water, rust stains or continuous discharge.

Common mistake: replacing with the same size after running out

If the old system regularly ran out of hot water, replacing it with the same size may repeat the issue.

Reassess the household’s actual demand before ordering.

Common mistake: choosing a heat pump without checking location

Heat pumps need outdoor airflow, condensate drainage and suitable noise placement.

A heat pump can be efficient but still unsuitable for a tight, enclosed or noise-sensitive location.

Common mistake: choosing instant gas without checking gas pipe sizing

Instant gas systems need suitable gas supply and water pressure.

A larger flow rate does not help if the gas pipework or water pressure cannot support it.

Common mistake: expecting instant hot water at every tap

Instant gas means the unit heats water on demand. It does not mean hot water arrives instantly at the tap.

Pipe length and plumbing layout can still create a wait.

Common mistake: DIY hot water installation

Hot water installation can involve plumbing, gas, electrical work, pressure control, scalding safety and compliance.

DIY installation can create:

Water leaks
Gas leaks
Electrical risks
Scalding risks
Warranty problems
Insurance issues
Non-compliant work
Poor performance
Property damage

Use the right licensed professionals.

Final verdict: what should you do if you have no hot water?

If you have no hot water, start with safe checks only. Confirm the system type, check power or gas supply where safe, look for leaks, note any error codes and work out whether the issue affects the whole home or only one outlet.

Call a licensed professional if there is a gas smell, leak, electrical fault, repeated breaker tripping, error code, fluctuating temperature or anything unsafe.

If the system is old, leaking, undersized or unreliable, replacement may be the better long-term option.

Compare Hot Water Systems, Electric Hot Water Systems, Gas Hot Water Systems, Instant Gas Hot Water Systems, Instant Electric Systems and Heat Pump Hot Water Systems to choose a system that better suits your household.

The best replacement is not always the same type or size you had before. It is the system that matches your energy source, water use, installation location and long-term cost expectations.

Long-tail FAQs

Why do I suddenly have no hot water?

Sudden no hot water may be caused by a tripped breaker, gas supply issue, failed heating element, pilot or ignition fault, thermostat issue, error code, heavy use, leak or system failure.

What should I check first if I have no hot water?

Check the system type, power supply, gas supply where relevant, visible leaks, error codes and whether the issue affects every hot tap or only one outlet.

Is no hot water an emergency?

It can be urgent if there is leaking, a gas smell, electrical fault, burning smell, repeated breaker tripping or safety concern. Stop using the system and contact the right licensed professional.

Why does my hot water run out quickly?

The system may be undersized, the household may be using more hot water than the tank can store, or there may be a fault with an element, burner, thermostat, timer or recovery cycle.

Why is my hot water only lukewarm?

Lukewarm water may be caused by a thermostat fault, tempering valve issue, failed element, gas burner problem, heat pump recovery issue, mixer tap fault or undersized system.

Why is my instant gas hot water not working?

Possible causes include no power, no gas, low water flow, low water pressure, blocked filter, ignition fault, error code, gas supply problem or internal component failure.

Why is my electric hot water not working?

Possible causes include a tripped breaker, failed element, thermostat issue, controlled-load supply problem, wiring fault, leaking tank or old system failure.

Should I repair or replace my hot water system?

Repair may suit newer systems with minor faults. Replacement may be better if the tank is leaking, the system is old, repairs are frequent, parts are costly, or the system no longer suits the household.

What hot water system should I choose after mine fails?

Choose based on energy source, household size, bathrooms, shower habits, installation location, gas supply, electrical supply, water pressure and budget. Compare electric, gas, instant gas and heat pump options.

Can I fix a hot water system myself?

Only do safe visual checks. Do not open covers, repair wiring, repair gas parts, replace elements, bypass safety controls or modify the system. Use licensed professionals for plumbing, gas and electrical work.

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