Hot Water Learning Center
Hot Water Help, Guides & Troubleshooting
Understand the problem, compare the options and know what to do next.
JR's Hot Water Learning Centre brings together our sizing tools, running-cost calculators, troubleshooting guides and technical explainers in one place. Start with the problem you are trying to solve, then go as deep as you need.
What Do You Need Help With?
Choose the closest match and we will point you to the most useful hot water guide.
These guides explain common residential hot-water problems and system choices. Gas, electrical, refrigeration and plumbing repairs should still be carried out by appropriately qualified trades where required.
Hot Water Help by What You Are Trying to Do
You do not need to know the technical name of the problem. Start with the outcome you want and work backwards.
Something Is Wrong
Start with no hot water, leaks, pressure, temperature or fault codes and narrow the problem down before deciding what needs repairing.
Diagnose Hot Water Problems →I Need a New System
Understand how the main hot-water technologies work, calculate the size you need and compare the long-term running-cost differences.
Start With System Sizing →Reduce Running Costs
Compare heat pumps, solar, electric and gas, then understand how tariffs, timers and rooftop solar change the economics.
Compare Running Costs →Repair or Replace?
Consider system age, the fault, tank condition, repair history and what a replacement would change before spending more money.
Repair or Replace Guide →JR Hot Water Learning Library
Search the full JR knowledge library or filter by choosing, costs, troubleshooting or system operation.
What Size Hot Water System Do I Need?
Work out how much hot water the household is likely to need and understand why storage tanks and continuous-flow systems are sized differently.
- Household size and usage
- Storage litres
- Recovery
- Instant gas flow sizing
Hot Water Running Cost Calculator & Comparison
Compare estimated hot-water running costs across electric, heat pump, solar, natural gas and LPG setups.
- Household-based estimates
- Tariffs and solar
- Annual and 10-year comparisons
- Technology differences
No Hot Water / Hot Water Not Working
Start here when the system has stopped producing hot water or the water has suddenly become cold or lukewarm.
- Electric faults
- Gas ignition
- Heat-pump problems
- Safe first checks
Repair or Replace a Hot Water System?
Decide whether another repair makes sense or whether age, condition and ongoing faults now favour replacement.
- System age
- Repair history
- Tank condition
- Replacement benefits
How Long Do Hot Water Systems Last?
Understand typical lifespan influences and the role of tank condition, corrosion, anodes, water quality and maintenance.
- Electric lifespan
- Gas lifespan
- Heat-pump lifespan
- End-of-life signs
Running Out of Hot Water
Find out why a system that still heats water may nevertheless run cold before the household has finished using it.
- Undersized storage
- Slow recovery
- Tariff restrictions
- Changed household demand
Leaking Hot Water System
Work out whether the water is coming from the tank, pipework, PTR valve, overflow or another source and how urgent it may be.
- Tank leaks
- PTR discharge
- Pipe and fitting leaks
- Repair vs replacement
Hot Water Pressure Problems
Separate a whole-house pressure problem from a hot-water-only issue or a fault affecting one tap or shower.
- Low hot-water pressure
- High pressure
- Valves and restrictions
- Instant-flow behaviour
Hot Water Temperature Problems
Understand the difference between storage and delivered temperature and diagnose water that is too hot, too cool or unstable.
- 50°C vs 60°C
- Tempering valves
- Thermostats
- Fluctuating temperature
Hot Water Tariffs, Off-Peak, Timers & Solar
Understand how controlled loads, timers, rooftop solar and heating schedules affect when a storage system uses electricity.
- Tariff 31 / CL1
- Tariff 33 / CL2
- Solar self-consumption
- Heat-pump timing
Hot Water Fault Codes & Common Errors
Understand what a displayed code can tell you, why codes differ between models and when repeated resetting should stop.
- Heat-pump errors
- Gas ignition faults
- Breaker and RCD trips
- Model-specific diagnosis
How Hot Water Systems Work & Types Explained
Learn how electric storage, heat pumps, gas storage, continuous-flow gas, solar thermal and instant electric actually produce hot water.
- Storage vs continuous flow
- Heat-pump refrigeration cycle
- System components
- Recovery and flow
Hot Water Troubleshooting: Start With the Symptom
Many hot-water faults overlap. The fastest way to narrow the cause is usually to begin with what the household can actually observe.
Heating & Capacity Problems
Use these when the main issue is whether the system is producing enough hot water.
Water, Pressure & Physical Problems
Use these where the heater still appears to operate but the plumbing behaviour has changed.
Choosing a Hot Water System: The Four Questions That Matter
Most replacement decisions become much easier when they are broken into size, technology, operating cost and installation suitability.
1. How Much Hot Water?
Start with household demand and work out whether the property needs a larger stored reserve, more recovery or greater continuous-flow capacity.
Hot Water Sizing Guide2. Which Technology?
Electric storage, heat pumps, gas storage, instant gas and solar all heat water differently and behave differently under household demand.
Compare How Systems Work3. What Will It Cost to Run?
Upfront price is only one part of the decision. Energy source, tariff, solar and household usage can create very different long-term costs.
Running Cost Calculator4. How Will It Be Powered?
Controlled load, general electricity, rooftop solar and timers can influence the ideal heating strategy for electric storage and heat pumps.
Tariffs & Solar GuideExisting System Still Working?
Age alone does not automatically mean replacement, but tank condition, repeated faults and repair economics matter.
Hot Water Lifespan GuideExisting System Has Failed?
Compare the likely repair with system age, remaining life and what a modern replacement would change.
Repair or Replace GuideA Simple Way to Research a New Hot Water System
You do not need to read every page. This four-step path covers the main decisions in the right order.
Understand the Types
Learn the difference between storage, continuous flow, heat pumps, gas and solar.
How Systems WorkCalculate the Size
Match capacity and recovery to the number of occupants and household usage.
Calculate System SizeCompare Running Costs
Compare energy technologies using the JR household running-cost calculator.
Compare Running CostsMatch the Energy Setup
Consider controlled load, timers and rooftop solar before deciding how the system should operate.
Compare Tariffs & SolarReady to Compare Actual Hot Water Systems?
Once you understand the technology, size and operating cost, move into the JR system ranges and compare the products available for each hot-water type.
Electric Hot Water
Conventional electric storage systems across common household capacities.
Compare Electric Systems →Heat Pump Hot Water
Efficient storage systems using refrigeration technology to transfer heat from surrounding air.
Compare Heat Pumps →Gas Hot Water
Compare both storage gas and continuous-flow gas options depending on how the household uses hot water.
Compare Gas Storage →Solar Hot Water
Solar thermal systems using roof collectors and stored hot water with backup boosting.
Compare Solar Systems →Hot Water Help & Learning Centre FAQs
Where should I start if my hot water system is not working?
Start with the No Hot Water / Hot Water Not Working guide. It separates complete loss of hot water from partial heating, electrical supply problems, gas ignition issues, heat-pump faults and temperature-control problems.
How do I know what size hot water system I need?
Start with household occupancy and typical hot-water usage. Storage systems are then sized around stored volume and recovery, while continuous-flow systems are sized around simultaneous litres per minute and the required temperature rise.
Which hot water system is cheapest to run?
Running cost depends on household demand, technology, tariff, solar generation and energy prices. Use the JR Hot Water Running Cost Calculator to compare different system and tariff combinations rather than relying on one universal answer.
How do I know whether to repair or replace my hot water system?
Consider the system age, tank condition, fault type, repair history, warranty, repair cost and the likely remaining service life. The Repair or Replace guide takes these factors through in detail.
Why do I keep running out of hot water?
Common reasons include insufficient storage capacity, changed household demand, slow recovery, restricted off-peak heating, heating faults or several showers occurring close together.
Is a leaking hot water system always a failed tank?
No. Water can come from valves, pipework, fittings, normal relief discharge or condensation as well as the storage vessel itself. The source of the water needs to be identified before deciding whether the tank has failed.
Why is my hot water pressure low?
Low pressure can come from the property supply, hot-water valves, pipe restrictions, temperature-control equipment or an individual tap or shower. Comparing hot and cold flow and checking whether all outlets are affected helps narrow the cause.
Why is my hot water too hot or not hot enough?
The heater's stored temperature and the temperature delivered at the tap are not necessarily the same. Thermostats, tempering valves, mixer cartridges and appliance controls can all affect the final temperature.
What does a hot water fault code mean?
Fault-code meanings depend on the exact brand and model. Record the complete code and model number before trying to interpret it because the same number can represent different faults across different appliances.
What is the difference between electric, gas, heat pump and solar hot water?
Electric storage uses a resistance element, gas systems use combustion, heat pumps use a refrigeration cycle to move environmental heat and solar thermal systems collect heat from sunlight. Continuous-flow systems also differ from storage systems because they heat water while it is being used.
How long should a hot water system last?
Lifespan varies with system type, tank construction, water quality, maintenance, operating conditions and component wear. The system's age should be considered together with its actual condition rather than used as the only replacement trigger.
Should I use Tariff 31, Tariff 33 or solar for hot water?
The best operating strategy depends on the specific water heater, household demand, electricity retailer, controlled-load arrangement, rooftop solar and when the household needs hot water. The tariff and timer guide explains each option.
From “What Is Wrong?” to “What Should I Install?” — Start Here
JR's Hot Water Learning Centre is designed to cover the complete decision journey: understand how the system works, diagnose common problems, calculate the right size, compare running costs, understand energy tariffs and decide when repair or replacement makes sense.