Having trouble with your Rinnai hot water system? It’s one of Australia’s most trusted hot water system brands, but if yours is on the blink, unfortunately you’re not alone. Remember, even the highest quality system will encounter problems if enough time passes. So whether you’ve got a Rinnai B26, a Hotflo electric, a sleek Infinity continuous flow, or a sophisticated Sunmaster solar system, our exclusive guide will walk you through how to identify and troubleshoot common issues – step by step. Rinnai hot water not working? Read on:
We’re going to run you through how to restore your Rinnai hot water:
- Quickly
- Safely
- Legally
- And efficiently.
Let’s get started:
Step 1: Identify your Rinnai system type
Before you can troubleshoot, it’s important to know what kind of Rinnai system you have. Rinnai’s range includes:
Rinnai Infinity: Gas continuous flow systems (eg. B16, B20, B26)
Rinnai Hotflo: Electric storage units (eg. 135L, 250L)
Rinnai Sunmaster: Solar hot water systems with gas or electric booster
Rinnai Enviroflo: Heat pump systems (less common in older homes).
Each model has different features – and different potential problems – so your Rinnai hot water system troubleshooting steps should match your unit.
For solar customers facing issues, Rinnai Sunmaster troubleshooting may also include:
- Checking roof sensors
- Cleaning collector panels
- Or resetting the booster controller.
Step 2: Check for error codes
Many Rinnai systems display error codes on a controller or blink patterns via LEDs. Common Rinnai error codes include:
Error 11 – No ignition: gas supply or flame sensor issue
Error 12 – Flame failure: often due to gas interruption or clogged burner
Error 16 – Over-temperature: blocked heat exchanger or restricted flow
Error 79 – Water sensor error: possible scale buildup or sensor failure.
To reset:
- Turn the unit off for 30 seconds
- Turn it back on
- If the error returns, continue with targeted troubleshooting or call a plumber for hot water repairs.
If you’re dealing with a Rinnai Infinity 26, many units include a visible Rinnai Infinity 26 reset button inside the access panel. Pressing this after addressing the root issue can often clear faults without needing tools.
If your model is an older Rinnai B20, and your problem isn’t solved after Googling ‘Rinnai B20 no hot water’, we’re not surprised!
First:
- Check that flow sensors are clean
- Confirm the unit is receiving gas and power.
These earlier models are sensitive to flow rate and ignition timing.
Step 3: No hot water? Start here
If the problem with your Rinnai hot water system not working is that the shower is stone cold, here’s what to check:
For the instant range:
- Rinnai gas hot water not working? The most common problem is that the gas is off!
- Check both at the meter and the appliance.
- Is there water flow? Systems only activate when flow rate exceeds about 2-3 L/min.
- Check the power supply. These systems need electricity for ignition.
- Inspect shower restrictors/tap aerators. Low flow can prevent ignition.
- If you hear clicking but no ignition, you may have a blocked burner, dirty flame sensor, or gas supply issue – common triggers for Error 11 or Error 12.
A Rinnai instant hot water not working is commonly related to one of the above flow or ignition faults.
Some homes still run older systems, so if your problem is Rinnai B16 no hot water, it’s often due to low flow, scale build-up or a dirty flame sensor.
For Solar Systems (eg. Sunmaster):
- Is there sunlight? Solar systems need sun to preheat water.
- Check the booster switch. Make sure gas or electric booster is on.
- Look at the controller. Many show alerts when the pump or sensor fails.
- Booster not kicking in? Try switching to manual boost.
- A failing solar pump or temperature sensor can cause lukewarm water and should be checked by a licensed plumber.
Step 4: Fluctuating water temperature
This is a common issue in hot water systems reviews, especially with older gas models. Here’s how to fix it:
Inconsistent water flow: Check taps, restrictors, and plumbing lines.
Blocked filter: Many Rinnai models have a cold-water inlet filter:
- Turn off the water
- Remove the filter
- Clean and reinsert.
Scale build-up: A common cause of Error 16. Scale restricts heat exchange and water flow.
Mixing valve fault: If water fluctuates between hot and cold, the tempering or thermostatic valve may be failing.
In units like the Rinnai B26, these fluctuations usually relate to flow rate issues, dirty sensors, or a temperature setting mismatch. Rinnai B26 no hot water? This is the most likely cause.
Step 5: Strange noises or leaks
Hot water leaking, gurgling, or humming noises can point to:
Internal scale: Common in hard water areas and affects all water heater brands.
Pressure relief valve (PRV) failure: Test your valve by lifting the tab – a steady trickle should come out.
Thermal expansion: Can cause popping noises in electric storage units.
Pump airlock (Sunmaster): Solar systems may trap air in circulation lines. Bleeding the system can help.
If the unit is leaking from the base or near the cylinder, especially in electric models like Hotflo, the tank may be failing – it’s time to replace the system.
Rinnai Hotflo electric water heater not working? The issue might be a failed thermostat or heating element. These units also need a functioning pressure valve and power supply.
Step 6: Electric units not heating
If your Hotflo electric storage system isn’t heating:
- Check the circuit breaker. Reset if tripped.
- Look at the thermostat. A failed thermostat or heating element is a common culprit.
- Test the booster switch on solar-electric boosted Sunmaster systems.
Electric units like Hotflo 250L are some of the best out there – but even great models need component replacement over time.
Sunmaster models sometimes suffer from intermittent heating, circulation faults, or controller failures – some of the most common Rinnai solar hot water problems in Australia.
Step 7: Prevent future problems
Want to avoid emergency callouts? Here’s how to extend your system’s life:
- Annual servicing: Especially important for continuous flow and solar models.
- Flush the system every 12-24 months: Clears scale and sediment.
- Replace anode rods in electric storage tanks every 5 years to prevent corrosion.
- Install a pressure reduction valve if your mains pressure is too high.
All hot water brands recommend regular maintenance – especially for units like the Rinnai Sunmaster, which involve both plumbing and solar tech.
Final Tip: Know when to call a plumber
While this guide should be super-helpful for basic checks, some issues simply require a licensed expert. Are you seeing:
- Repeated error codes?
- No ignition at all?
- Leaking from internal components?
Don’t risk your safety and instead call in a pro.
Not sure if you’ve done everything right from our guide? Tried a Rinnai Infinity 26 troubleshooting reset? Flushed the filters? Checked the sensor wires? Still without hot water?! It’s time to reach out to S&J Plumbing and Gasfitting.
Our friendly team is experienced with all major hot water system brands, including Rinnai. We provide:
- Expert diagnostics
- Fast repairs
- And complete system replacements.
And everything we do is backed by our solid commitment to long-term solutions – not quick band-aid fixes.
Need Rinnai hot water repairs?
If your Rinnai system is acting up, don’t wait for a cold shower to ruin your day. Contact the friendly team at S&J Plumbing and Gasfitting for expert troubleshooting, repairs and full replacements. We’ll get your hot water flowing again – safely, efficiently, and with no guesswork.