Is it ok to use a vinegar solution for descaling the Noritz EZ98, or should I use a specific descaling agent?

It's generally not recommended to use a vinegar solution for descaling the Noritz EZ98 tankless water heater, or any tankless water heater for that matter. While vinegar is a common household acid that can effectively remove mineral deposits and scale, it may not be the best choice for descaling tankless water heaters due to several important reasons:

Acid Concentration: Vinegar contains acetic acid, which is relatively weak compared to commercial descaling agents specifically formulated for tankless water heaters. Hard water scales can be quite stubborn and may require a stronger acid to effectively dissolve and remove it. Using a descaling agent designed for tankless water heaters ensures that the scale is thoroughly removed.
Effectiveness: Vinegar may not be as effective at removing heavy or stubborn scale deposits as specialized descaling agents. Tankless water heaters often have narrow and intricate pathways within the heat exchanger and plumbing components, making it crucial to use a descaling agent that can reach and dissolve all scale buildups effectively.
Residue and Odor: Vinegar can leave behind a noticeable odor that can persist even after thorough flushing. Additionally, it may leave behind residues that can affect water taste and quality. Commercial descaling agents are formulated to minimize these issues, providing a more thorough and odor-free descaling process.
Potential Corrosion: While vinegar is a relatively mild acid, it is still an acid and can potentially corrode certain materials over time if not thoroughly rinsed. Tankless water heaters have various components, including metal parts and sensitive electronic elements. A specialized descaling agent is less likely to cause unintended corrosion when used as directed.
Given these considerations, it's advisable to use a specific descaling agent designed for tankless water heaters when performing descaling maintenance on your Noritz EZ98. These commercial descaling agents are formulated to be effective at dissolving scale without causing harm to the unit or leaving unwanted residues or odors.
Here's a general process for descaling your Noritz EZ98 using a specialized descaling agent:
Turn Off the Water Heater: Ensure that the tankless water heater is turned off and disconnected from the power source.
Access the Heat Exchanger: Depending on the specific model and installation, you may need to remove access panels or covers to reach the heat exchanger.
Prepare the Descaling Solution: Follow the manufacturer's instructions on the descaling agent packaging to prepare the solution. Typically, you'll mix the descaling agent with water to create the proper concentration.
Circulate the Solution: Using a pump or a circulation system, circulate the descaling solution through the heat exchanger and plumbing components. Follow the recommended circulation time and intervals provided by the manufacturer.
Rinse Thoroughly: After the descaling process, flush the system with clean water multiple times to ensure that all traces of the descaling solution are removed.
Reassemble and Restart: Reassemble any removed parts or access panels and reconnect the water heater to the power source. Restart the unit and check for proper operation.
Regular Maintenance: Keep track of the manufacturer's recommended maintenance schedule and perform descaling as needed to prevent scale buildup and maintain the efficiency of your tankless water heater.

In summary, while vinegar is a household acid that can be used for various cleaning purposes, it's not the ideal choice for descaling a tankless water heater like the Noritz EZ98. Using a specialized descaling agent designed for tankless water heaters ensures effectiveness, minimizes potential issues, and helps prolong the lifespan and efficiency of the unit. Always follow the manufacturer's guidelines and recommendations for descaling and maintenance to maintain the optimal performance of your tankless water heater.