February 18, 2026 — A consumer has reported a concerning incident involving a Rinnai RE-180iN tankless water heater, citing loud combustion noise upon activation. The incident report details that a factory-authorized plumbing company determined the unit, labeled for natural gas, was allegedly operating in propane mode, raising significant safety concerns.
Product Details
Incident Overview
The incident occurred following the purchase and installation of a Rinnai tankless water heater. The consumer reported experiencing a “loud combustion noise” whenever the unit fired on demand. Concerned by this unusual sound, the consumer promptly contacted a factory-authorized plumbing company to investigate the issue.
According to the consumer’s report, discussions with a factory service agent revealed that the Rinnai unit, although labeled for natural gas, was allegedly operating in propane mode. The consumer explicitly characterized this situation as “dangerous!!!!!!!!!!!” due to the inherent risks associated with operating a gas appliance with the incorrect fuel type.
Safety Concerns
Operating a gas-fired appliance, such as a tankless water heater, with a gas type it is not designed for poses severe and immediate safety concerns:
- Combustion Instability and Loud Noises: As reported, the loud combustion noise is a direct indicator of improper fuel mixture and combustion. This can lead to inefficient operation and, more critically, uncontrolled burning.
- Fire and Explosion Hazard: When a natural gas appliance operates on propane (or vice-versa) without proper conversion, the air-to-fuel ratio becomes dangerously imbalanced. Propane requires more air for complete combustion than natural gas. If a natural gas appliance receives propane, it will operate with too little air, leading to incomplete combustion, potential flame rollout, and significant risk of fire or even explosion due to unburnt gas accumulation.
- Carbon Monoxide Poisoning: Incomplete combustion is a primary cause of carbon monoxide (CO) production. CO is a colorless, odorless, and highly toxic gas that can be fatal when inhaled. Operating an appliance with the wrong fuel type significantly increases the risk of CO emissions into living spaces, potentially affecting all occupants.
- Property Damage: Malfunctioning combustion can lead to overheating of the appliance and surrounding materials, potentially causing damage to the unit itself, plumbing, and nearby structural elements.
The potential for such hazards underscores the critical importance of ensuring that gas appliances are installed and operated strictly according to their designed fuel type.
What Consumers Should Do
If you own a Rinnai RE-180iN tankless water heater or any gas appliance, and you experience unusual operating sounds or suspect a gas type mismatch:
1. Immediate Action: If you hear loud combustion noises or suspect any malfunction related to gas supply, immediately turn off the gas supply to the water heater and, if possible, the main gas supply to your home. Do not attempt to operate the appliance.
2. Verify Gas Type: Confirm the type of gas supplied to your home (natural gas or propane). Check the rating label on your Rinnai tankless water heater to ensure it matches the gas type used in your residence. The label is typically found on the side or front of the unit.
3. Contact a Qualified Professional: Do NOT attempt to diagnose or fix the issue yourself. Contact a licensed and qualified HVAC technician or plumber who is certified to work with gas appliances, specifically tankless water heaters. They can properly inspect the unit, verify gas type compatibility, and ensure safe operation.
4. Install CO Detectors: Ensure you have working carbon monoxide detectors installed on every level of your home, especially near sleeping areas. Test them regularly.
5. Report the Incident: If you experience a similar issue, report it to the manufacturer and the U.S. Consumer Product Safety Commission (CPSC) at www.cpsc.gov.
Manufacturer’s Response
RINNAI AMERICA CORPORATION provided a response on February 6, 2026, stating the following:
“The claim is that the consumer purchased a tankless water heater labeled as Natural Gas when it was operating in propane mode. There is no propane mode for this product. There are component differences from one gas type to the other that dictate the utility requirement. Additionally, these component differences are verified both physically and from a performance perspective when the product is manufactured. It is only when these performance tests are successfully performed that the product label is printed.
Additionally, there is no record of the any call to Rinnai’s Customer Care.
Rinnai has an extremely robust system in place to verify the accuracy of our manufacturing processes and guarantee that our product meets our rigorous quality standards. We stand behind our product in every way.”
The manufacturer’s response indicates a discrepancy in the understanding of the issue, stating that their natural gas products do not have a “propane mode” and are rigorously tested and verified for the labeled gas type during manufacturing. They also noted no record of a call to their Customer Care regarding this incident.
Legal Help Available
If you or a loved one has been injured by a defective product or suffered property damage due to a product malfunction, you may be entitled to compensation. The experienced product liability attorneys at Farzan Law understand the complexities of defective product cases and can help you navigate the legal process. Farzan Law is a California based Personal Injury law firm focusing on protecting the rights of those wrongfully injured.
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Contact us today for a free consultation: 424-325-3112
Our legal team has successfully represented clients in product liability cases involving defective appliances, automotive defects, medical devices, and consumer products. We work on a contingency fee basis, which means you don’t pay unless we win your case.
Note: This information is based on incident reports provided by the U.S. Consumer Product Safety Commission. If you find information that is incorrect, please contact us immediately so we can correct the post to reflect accurate information.
Disclaimer: The information provided in this post is not intended to be legal or medical advice. This article is based on publicly available incident reports. The incidents mentioned have not necessarily been independently verified or adjudicated.