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Almost half of Brisbane’s plumbing callouts involve hot water issues. When your Rinnai stops heating, it can disrupt the whole household. The good news is that most problems are easy to identify, and many can be fixed with a few simple checks. Before you call a plumber, try these steps to get your hot water back.
Understanding How Your System Works
Rinnai units are designed to deliver steady, efficient performance in Brisbane’s warm and humid climate. The exclusive Rinnai range includes gas, electric, solar and heat pump models that suit a wide variety of homes. Each relies on three essentials: a consistent gas or power supply, stable water pressure and unrestricted flow.
Popular options like the Rinnai Infinity continuous-flow heater heat water on demand. Knowing how these systems operate helps you spot what’s gone wrong when hot water suddenly turns cold.
Common Reasons Hot Water Stops Working
In many cases, the cause is surprisingly simple. A closed gas valve, low gas pressure or an empty LPG bottle can cut off the flame in gas models. For electric units, a tripped circuit breaker or power outage may be to blame.
Blocked inlet filters and low water flow are also common culprits, preventing the burner from igniting. Faulty controllers, damaged thermostats or incorrect temperature settings can leave you with lukewarm water instead of a proper shower.
Most continuous-flow systems need a minimum water flow to start heating, so even a restricted tap can interrupt the process. Recognising these small issues helps you troubleshoot before paying for unnecessary repairs.
Step-by-Step Troubleshooting Guide
Try these simple checks before you call a plumber:
- Check the power supply. Make sure the system is plugged in, the circuit breaker is on, and the “water heater” switch hasn’t been turned off.
- Check the gas supply. Look at your gas meter or LPG bottles and confirm the valve is open. If the bottles are nearly empty, replace them.
- Reset your unit. Switch it off for about a minute, then turn it back on. This clears many temporary faults.
- Clean the inlet filter. Sediment can block water flow and prevent heating. Remove and rinse the filter to restore pressure.
- Check the controller. Look for error messages or flashing codes on the display.
- Run several hot taps. Low flow may stop ignition, so make sure there’s enough water moving through the system.
If you still have no heat or see recurring errors, it’s time to call in a professional.
Understanding Error Codes
Most modern heaters show error codes to make troubleshooting easier. These codes display on the controller and indicate what’s wrong. Below is a table of the Rinnai codes you can check, and for your reference
Rinnai Hot Water System Error Codes
| Error Code | Meaning / Fault | Possible Cause / Action |
|---|---|---|
| 03 | Power interruption during bath fill | Restart unit and refill; check power supply stability. |
| 05 | Bypass valve failure | Check for valve obstruction or replace bypass valve. |
| 07 | Circulation pump issue (models with recirc) | Inspect circulation pump and filter for blockage. |
| 10 | Air supply or exhaust blockage | Check venting for obstructions; ensure flue terminal is clear. |
| 11 | Ignition failure | Check gas supply, burner, and ignitor; reset and retry. |
| 12 | Flame failure | Gas interruption, dirty flame sensor, or vent obstruction. |
| 14 | Thermistor fault (water temperature sensor) | Replace or inspect thermistor connection. |
| 16 | Overtemperature warning | Check for scale buildup or low water flow causing overheating. |
| 19 | Electrical grounding / power supply error | Ensure correct polarity and reliable power source. |
| 25 | Condensate trap or drain block | Clean condensate trap; ensure proper drainage. |
| 32 | Outgoing water temperature sensor fault | Check thermistor; may need replacement. |
| 33 | Heat exchanger sensor fault | Inspect wiring to heat exchanger thermistor; replace if faulty. |
| 34 | Combustion air temperature sensor fault | Clean sensor or replace; check airflow restriction. |
| 35 | Heater sensor fault | Thermistor connection issue on heater circuit. |
| 38 | CO2 abnormality detected | Check burner combustion; service by technician. |
| 41 | Inlet water temperature thermistor fault | Replace or reconnect inlet sensor. |
| 42 | Low water flow | Ensure sufficient flow rate (>2.5 L/min); clean filters or aerators. |
| 43 | Abnormal circulating system | Check pump and valves for correct function. |
| 61 | Combustion fan motor fault | Fan seized, blocked, or wiring issue; inspect and clean. |
| 65 | Water flow control fault | Check water control valve motor or flow sensor. |
| 71 | Solenoid valve circuit fault | Gas valve or wiring failure; needs gas technician inspection. |
| 72 | Flame sensing circuit fault | Check flame rod for corrosion; replace if damaged. |
| 73 | Communication error with internal components | Inspect wiring harness and PCB communication lines. |
| 79 | Fan speed deviation or sensor error | Service fan unit; check bearings and hall sensor. |
| 80 | Improper gas combustion | Check gas pressure, burner, and venting; technician required. |
| 90 | Abnormal combustion (CO or pressure issue) | Immediate shutdown—inspect flue, gas pressure, and venting. |
| 91 | Abnormal circuit board operation | Reset unit; if persists, replace PCB. |
| 92 | Open circuit in modulating gas solenoid | Technician to check solenoid valve circuit and wiring. |
| 99 | High combustion level detected (CO safety) | Stop using; service unit for combustion calibration. |
⚠️ Always isolate power and gas supply before any servicing. If uncertain, contact a licensed Rinnai technician.
Rinnai Tankless Hot Water System Error Codes
This guide lists diagnostic codes specific to Rinnai tankless / continuous flow water heaters. If an error persists after a reset or basic maintenance, contact a qualified Rinnai service technician.
| Error Code | Fault Description | Probable Cause / Recommended Action |
|---|---|---|
| 10 | Air supply or exhaust blockage | Inspect flue terminals and vent pipes for debris, ice, or obstructions. |
| 11 | Ignition failure | Check gas flow, igniter, burner, and proper gas pressure; reset unit. |
| 12 | Flame failure | Possible poor gas supply, dirty flame rod, or blocked vent; service required. |
| 14 | Thermistor fault (water temperature) | Faulty or disconnected water temperature sensor; check wiring or replace thermistor. |
| 16 | Overtemperature / heat exchanger limit | Scale buildup or low flow; descale and verify minimum flow rate. |
| 25 | Condensate trap fault (condensing models) | Inspect and clear condensate line or trap blockage. |
| 32 | Outlet thermistor fault | Check thermistor for secure connection; replace if defective. |
| 33 | Heat exchanger thermistor fault | Loose or faulty heat exchanger sensor; inspect harness. |
| 34 | Combustion air temperature sensor fault | Dirty or failed sensor; ensure proper air circulation and replace if needed. |
| 35 | Heater thermistor fault | Inspect thermistor and wiring; replace if damaged. |
| 41 | Inlet water thermistor fault | Inlet sensor open or short; verify connection or replace. |
| 42 | Low water flow / flow sensor issue | Clean inlet water filter; confirm flow above 2.5 L/min. |
| 61 | Combustion fan motor fault | Fan may be seized, blocked, or wiring failed; inspect and clean blades. |
| 65 | Water flow control failure | Fault in flow control valve motor or sensor; technician to inspect valve assembly. |
| 71 | Solenoid valve circuit fault | Gas valve coil open/shorted or PCB fault; service by gas technician. |
| 72 | Flame sensing circuit fault | Dirty flame rod or damaged lead; clean or replace sensor. |
| 79 | Fan speed deviation / sensor fault | Faulty fan speed detector or fan obstruction; service required. |
| 80 | Improper combustion | Incorrect gas‑air ratio, dirty burner, or blocked vent; needs professional service. |
| 90 | Abnormal combustion (CO or pressure issue) | Potential CO hazard — shut off and have unit serviced immediately. |
| 92 | Open circuit in gas modulating valve | Check modulating solenoid wiring and resistance; most often PCB or valve fault. |
| 99 | High combustion level / CO safety shutdown | Stop using heater until inspected; recalibration required. |
You can find full explanations in the owner’s manual or on Rinnai’s website. Some codes will clear after turning the system off and on again or by closing the tap for a moment. Repeated or unfamiliar codes should always be checked by a licensed plumber.
Gas, Electric and Hybrid Models
Not every system works the same way, so your troubleshooting approach should match your model type.
Gas heaters are common across Brisbane. Ensure the gas valve is open and the pilot light burns with a steady blue flame. If you see error codes 11 or 12, it may point to ignition problems or low gas pressure. Brisbane’s gas supply can vary slightly between suburbs, which sometimes affects performance. Never try to adjust gas lines yourself. Call a qualified hot water plumber.
Electric, solar and heat pump systems rely on consistent power. Check that the “hot water” switch is on at your switchboard and that the thermostat hasn’t failed. For solar systems, confirm that the booster or backup heater is working. If your model combines gas and electric components, both must be functioning for reliable heating.
When to Call a Brisbane Plumber
Sometimes, simple fixes are not enough. If you’ve worked through the basics and still have no heat, it’s time for professional help. Qualified Brisbane plumbers can test gas valves, inspect sensors and safely complete any hot water repairs. They’ll also check for leaks, damaged wiring and low gas pressure.
If your system is over ten years old, struggles to maintain temperature or shows frequent error codes, replacement may be the smarter choice. A professional can recommend whether repair or replacement makes better long-term sense for your home.
Keeping Your System in Good Shape
Regular maintenance helps avoid future breakdowns. Clean the inlet filter at least twice a year to prevent blockages. Flush the heater to remove sediment, and check your gas fittings for leaks or corrosion.
Keep an eye on water flow through your taps, as reduced pressure can cause temperature fluctuations. If your hot water feels inconsistent, inspect the thermostat and controller. Addressing small changes early helps you maintain steady performance and extends your unit’s lifespan.
When It’s Time for an Upgrade
Even well-maintained heaters don’t last forever. If yours produces lukewarm water, requires constant attention or is nearing the end of its warranty, a new model may be worth considering. Modern Rinnai gas and electric units are more energy-efficient, provide consistent hot water and include built-in safety features.
Upgrading can also reduce ongoing repair costs, especially if your current system has been running for more than a decade. In Brisbane, a properly sized and installed replacement ensures comfort and reliability through all seasons.
Get Expert Help from All Kind Wastewater
If your system still isn’t working after these checks, contact All Kind Wastewater. Our Brisbane team includes licensed plumbers who handle gas, electric, solar and hybrid hot water systems. We repair faulty valves, fix flow problems and replace worn components quickly.
Whether your issue involves a power fault, gas supply problem or full system replacement, our experienced tradespeople can get you back to enjoying reliable hot water. Call All Kind Wastewater today to book a service anywhere in Brisbane.
FAQs
1. What does error code 12 mean?
It means the flame has failed or the gas pressure is too low for ignition.
2. Can I reset my system myself?
Yes. Turn off the power for a minute, then switch it back on. This often clears temporary faults.
3. Why is the water only lukewarm?
A blocked inlet filter, a failing thermostat or inconsistent gas pressure are the usual causes.
4. How long do these systems last in Brisbane?
With regular maintenance, most last ten to fifteen years before needing replacement.
