If your Thermann unit is playing up, that’s bad news – because it really is a great Aussie brand. Owned by market leader Reece, Thermann hot water systems are made by other great manufacturers like Rinnai and with affordable price-points. You do, however, sometimes need to do a touch of Thermann hot water system troubleshooting – and you’ve definitely found the right place.
In our exclusive and ultimate guide, we’ve covered absolutely everything that goes wrong with Thermanns – from error messages to cold water issues and beyond – no matter what model you’re running. This includes Australia’s best selling Thermanns including:
- The Thermann 20L G-Series continuous flow gas unit
- The Thermann 250THM1 electric system
- The Thermann 250L gas-boosted solar
- The Thermann X-split heat pump
- The Thermann 315THM1 electric – and many more.
Whether you have a gas, electric, solar, heat pump, or continuous flow system, we’ll walk you through the common problems, the potential fixes – and when to call in the friendly team at S&J Plumbing and Gasfitting.
1. Identify your Thermann system
Before attempting any troubleshooting, figure out what kind of Thermann hot water system you have. Thermann offers several types of hot water systems in Australia:
- Gas storage systems
- Electric storage systems
- Continuous flow (gas)
- Solar boosted systems
- Heat pump systems.
Each type has different components and diagnostic steps, so knowing your system type will help you apply the right fix or contact the right service.
2. No hot water? Check these first
If you’ve turned on the tap and you have a Thermann hot water not working – evidenced by icy cold water – it might be caused by something simple. Then again, it could be a larger system fault.
Start with these basics:
Power/Gas supply: For electric units, check your switchboard for a tripped breaker. For gas systems, ensure your gas valve is open.
Water supply: Confirm that your mains water is on and flowing properly.
System type: Instantaneous units won’t provide hot water unless a tap is running with sufficient flow.
3. System not heating properly
A common complaint is a Thermann hot water system not heating consistently. If your water is lukewarm, fluctuating, or just takes too long to heat up, try these checks:
Storage Systems: It could be a failed heating element (electric) or burner fault (gas).
Instantaneous Systems: Low flow, dirty filters, or ignition issues could be the cause.
Heat Pumps/Solar Systems: These rely on environmental conditions and backup boosters – if the sun or air temperature drops, expect slower heating unless the booster is working properly.
4. Resetting your Thermann unit
Sometimes a simple reset can get your system back online. If you’re unsure how to turn on Thermann water heater or perform a reset, refer to the manual for your particular model.
But you can also just look for the Thermann hot water system reset button – typically located behind an access panel or on the digital display panel of many models (especially heat pumps and continuous flow units).
Have you had a:
- Recent power outage?
- Temperature spike?
- Or fault code display?
Pressing the Thermann reset button may restore normal operation.
5. Error codes & fault indicators
Modern Thermann systems, especially the continuous flow and heat pump models, display digital fault codes. These codes indicate exactly what’s wrong – such as:
- Ignition failure
- Blocked flue
- Or overheating.
If you see an error code:
- Reset the unit once.
- If the code returns, do not keep resetting – you may make the issue worse.
- Take a photo of the display and call your local expert.
S&J Plumbing and Gasfitting can diagnose all Thermann error codes – and we carry many spare parts for urgent repairs all across Brisbane.
6. Leaking or dripping system
A leaking Thermann system isn’t always a disaster – but it should never be ignored. Here’s what to look out for:
Pressure Temperature Relief (PTR) valve: A small amount of dripping is normal, especially after heating.
Visible tank leaks: Water pooling under the tank or on connections usually indicates corrosion or seal failure.
Pipe joins: Leaks from fittings may be fixable without replacing the whole unit.
If you’re unsure whether it’s normal condensation or a more serious hot water leak, get it checked by S&J.
7. Thermostat issues: Location & adjustment
If your water is too hot or not hot enough, you might be wondering about the Thermann hot water system thermostat location. For storage systems, the thermostat is often located behind the lower front panel or near the heating element. Instantaneous and heat pump models use electronic temperature settings, typically on a wall controller or digital panel. And in some cases, it’s not possible to adjust the temperature manually.
Need to make changes? Thermann thermostat adjustment should always be handled with care:
- The recommended setting is 60°C for safety and Legionella prevention.
Do not exceed 50°C at taps – especially for households with children or elderly residents.
If unsure, contact a professional – tampering with some thermostats may void your warranty or breach safety laws.
8. What’s that noise?
Some systems – particularly heat pumps – make low humming or fan-like noises during operation. This is normal. However, are you hearing:
- Loud banging?
- Gurgling?
- Hissing?
These can indicate sediment build-up, air in the system, or component wear.
Refer to your manual for your specific model’s expected operating sounds. If the noise is persistent or worsening, get it checked to avoid long-term damage.
9. When to call in a professional
If you’ve worked through the above steps and still have issues, you’ll need help from a qualified plumber. S&J Plumbing and Gasfitting are your local Thermann specialists in Brisbane and beyond – equipped to handle:
- Gas compliance issues
- Electrical faults
- Valve and thermostat replacements
- Safety checks and routine servicing.
We recommend a professional Thermann hot water service every 12 months to keep your system running safely and efficiently.
10. Is it still under warranty?
Don’t forget to check your Thermann hot water system warranty before paying for repairs. Thermann systems sold in Australia typically offer:
- 5-12 years on storage tank cylinders
- 3-5 years on parts and labour
- 1 year on accessories or controllers
You’ll need your purchase date, model/serial number (usually on the nameplate), and proof of installation. S&J Plumbing can help you out with the warranty claim process, including documentation and inspection reports.
11. Common Thermann problems by system type
Here’s a quick summary of the most frequent Thermann problems based on unit type:
Gas Storage:
- Pilot light won’t stay on
- Rusty water (due to anode corrosion)
- Burner not firing
Electric Storage:
- Tripped circuit breaker
- Faulty heating element
- Noisy tank (sediment build-up)
Continuous Flow:
- Intermittent hot water
- Error codes (e.g. ignition or flow rate issues)
- Blocked inlet filters
Heat Pump:
- Slow recovery time in cold weather
- Fan noises or refrigerant warnings
- Booster not activating
Solar:
- Water not reaching temperature (especially in winter)
- Airlocks or blockages
- Booster not switching on
Need help with your Thermann unit?
Tried everything and your Thermann still isn’t performing? Don’t guess or risk further damage! Whether it’s a quick fix, part replacement, or full system replacement, S&J Plumbing and Gasfitting is always right here to help.
We’re fully licensed, local, and familiar with all Thermann models. From emergency repairs to full system diagnostics, we bring expert knowledge and fast service all across Brisbane, including Brisbane Northside, Brisbane Southside, Logan, Moreton Bay, Redland Bay, and Ipswich. Call S&J Plumbing and Gasfitting today – and get your hot water running again … the right way.