Hot Water Learning Center
Hot Water Learning Centre
Find the answer, calculator or troubleshooting guide you need before choosing your next hot water system.
From choosing the right size and comparing running costs to fixing pressure, temperature, leaks, fault codes and systems that keep running out — start with the question that matches your situation.
What Do You Need Help With?
Choose the question closest to yours and jump directly to the calculator, checker or guide.
Calculate household demand.
COST What Will It Cost to Run?Compare running costs.
TARIFFS Off-Peak, Tariffs & TimersUnderstand heating times.
NOT WORKING No Hot Water?Check why it stopped.
TEMPERATURE Too Hot or Not Hot Enough?Diagnose temperature issues.
PRESSURE Hot Water Pressure ProblemsFind the likely restriction.
LEAKS Hot Water System Leaking?Find where the water is coming from.
DECISION Repair or Replace?Compare the smarter option.
LIFESPAN How Long Should It Last?Check age and condition.
LEARN How Do Hot Water Systems Work?Electric, heat pump, gas & solar.
FAULT CODES What Does My Error Code Mean?Look up common faults.
CAPACITY Hot Water Keeps Running Out?Check capacity vs recovery.
Start With What You're Trying to Do
You do not need to understand hot-water terminology first. Choose whether you are buying, comparing costs, troubleshooting a problem or simply trying to understand how your system works.
Choose a System
Work out the required size, understand lifespan and decide whether repairing the old unit still makes sense.
View choosing guides → 2Understand Costs
Compare electricity tariffs, heating schedules and long-term operating costs before buying.
View cost guides → 3Fix a Problem
Diagnose no hot water, leaks, pressure, temperature, running-out problems and displayed fault codes.
View troubleshooting → 4Learn How It Works
Understand storage, recovery, heat pumps, gas, solar, continuous flow and the components inside the system.
Learn the basics →Hot Water Calculators
If you are choosing a replacement system, start with the two questions that matter most: how much hot water does the home need and what will each technology cost to operate?
Hot Water Sizing Calculator
Estimate household demand and compare electric storage, heat pump, gas storage, continuous flow and other suitable options.
Calculate the right size →Running Cost Calculator
Compare expected energy costs across common hot-water technologies and see how tariffs and solar PV can change the result.
Compare running costs →Choosing, Sizing & Replacement
Decide what the home actually needs before choosing a brand or model.
What Size Hot Water System Do I Need?
Calculate household hot-water demand and compare suitable storage, heat-pump and continuous-flow sizing approaches.
Find the right size DECISION TOOLRepair or Replace a Hot Water System?
Compare system age, fault type, repair history, capacity and running costs before spending money on the old unit.
Compare repair vs replacement OWNERSHIP GUIDEHow Long Do Hot Water Systems Last?
See how age, water quality, maintenance, corrosion and repair history affect expected system life.
Check system lifespanRunning Costs, Tariffs & Heating Times
Understand what the system costs to operate and when it should heat.
Hot Water Running Cost Calculator
Compare electricity, heat pump, gas and solar hot-water running costs over daily, annual and longer ownership periods.
Compare running costs ENERGY GUIDEHot Water Tariffs, Off-Peak & Timers
Understand controlled loads, heating windows, timers, rooftop solar and when electric or heat-pump systems should operate.
Understand tariffs & timers CAPACITY GUIDEWhy Does My Hot Water Keep Running Out?
Separate tank-size problems from slow recovery, restricted heating periods, increased demand and actual component faults.
Diagnose running outHot Water Troubleshooting
Start with the symptom you can see or feel. You do not need to diagnose the technical component before choosing the right guide.
No Hot Water / Hot Water Not Working
Start here if the system has stopped heating completely, produces only lukewarm water or appears to have failed.
Check why it stopped working TEMPERATUREHot Water Temperature Problems
Troubleshoot water that is too hot, not hot enough, lukewarm or changing temperature unexpectedly.
Diagnose temperature problems PRESSUREHot Water Pressure Problems
Compare low hot-water pressure, one-tap issues, whole-house pressure problems and possible restrictions.
Diagnose pressure problems LEAK CHECKERLeaking Hot Water System
Identify whether water is coming from the tank, relief drain, valve, pipe connection or heat-pump condensate.
Check the leak source CAPACITYHot Water Running Out Too Quickly
Find out whether the household is exceeding storage and recovery or whether the system has recently lost heating performance.
Find the cause ERROR CODESHot Water Fault Codes & Common Errors
Understand displayed heat-pump and gas fault codes and why the exact brand and model matter before interpreting them.
Look up a fault codeUnderstand Your Hot Water System
If you want to understand why different hot-water technologies behave differently, start with how energy enters the system, whether the water is stored, and how quickly lost heat can be replaced.
How Hot Water Systems Work
Learn how electric storage, heat pumps, gas storage, continuous-flow gas and solar hot-water systems heat and deliver water.
See how each system works SYSTEM LIFEHot Water System Lifespan
Understand why tank condition, water quality, installation and maintenance matter more than one fixed expiry age.
Understand system life ENERGY CONTROLOff-Peak, Timers & Controlled Loads
Learn why two identical storage tanks can behave differently when one can reheat all day and another only has restricted electricity.
Understand heating schedulesA Better Way to Research Hot Water
Start with the problem or decision, understand the important variables, then compare actual systems. That avoids choosing a unit based only on brand, tank litres or the cheapest advertised price.
Identify the Need
Are you replacing a failed system, fixing a fault, reducing running costs or planning ahead?
Use the Right Tool
Calculate size, compare operating cost or use a symptom checker before looking at individual products.
Compare Technologies
Understand how electric, heat pump, gas and solar options differ in storage, recovery and energy use.
Compare Actual Systems
Once the requirements are clear, compare models that genuinely suit the home rather than starting with a product and working backwards.
Finished Researching? Compare Hot Water Systems
Use what you have learned to narrow the market by technology and choose products that match the household instead of simply replacing the old unit with the closest equivalent.
Move From Research to the Right Product
Compare hot-water options by technology, household demand, installation requirements and operating cost.
Hot Water Learning Centre FAQs
Where should I start when choosing a new hot water system?
Start by estimating household hot-water demand and determining whether the existing system's size and technology still suit the home. Then compare purchase cost, running cost, recovery and installation requirements.
How do I know what size hot water system I need?
Size should be based on household demand, peak use, number of occupants, bathrooms, baths, simultaneous showers and the heating and recovery characteristics of the chosen technology.
Which hot water system is cheapest to run?
Running cost depends on technology, energy tariffs, household demand, operating schedule and whether rooftop solar is available. Use the running-cost calculator to compare the likely operating cost for the household.
Why is my hot water system not working?
Possible causes include loss of electricity or gas supply, heating component faults, timers, heat-pump controls, burner faults, temperature controls or other appliance problems. Start with the No Hot Water checker.
Why does my hot water keep running out?
The system may be undersized, household demand may have increased, recovery may be too slow, heating periods may be restricted or the system may no longer be heating normally.
Should I repair or replace an old hot water system?
Consider the system's age, tank condition, fault type, repair history, repair cost, reliability, capacity and running cost together rather than replacing it based on age alone.
How do heat pump hot water systems work?
A heat pump uses a refrigeration cycle to absorb heat from surrounding air and transfer it into stored water. Electricity powers the compressor, fan and controls while much of the thermal energy comes from the surrounding air.
Can I look up a hot water fault code online?
Yes, but the code must be matched to the correct manufacturer and model because the same letters or numbers can represent different faults on different appliances.
Understand It First. Buy the Right Hot Water System Second.
Use the guides and calculators to work out what the home actually needs, then compare suitable systems, installation options and pricing with Installed Today.
