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Condensing vs. Non-Condensing Tankless Water Heaters

When it comes to choosing a tankless water heater, one of the key decisions homeowners face is between condensing and non-condensing models. Understanding the differences between these two types of water heaters is crucial for selecting the right one for your needs, ensuring energy efficiency, and optimizing long-term savings.

What are Condensing Tankless Water Heaters?

Condensing tankless water heaters are designed to capture and utilize the energy from exhaust gases that would otherwise be wasted. These heaters have a secondary heat exchanger that condenses the exhaust gases to extract additional heat, pre-warming the incoming cold water. This process enhances efficiency, with many models achieving energy efficiency ratings of 90% or higher.

Benefits of Condensing Models:

  • Higher Efficiency: By utilizing exhaust gases, condensing models are more energy-efficient, reducing energy bills.
  • Environmental Impact: Lower greenhouse gas emissions due to better energy utilization.
  • Reduced Venting Costs: Since the exhaust gases are cooler, PVC pipes can often be used for venting, which is less expensive than the stainless steel venting required for non-condensing models.


  • Higher Initial Cost: Condensing units are generally more expensive upfront due to their complex design.
  • Maintenance Requirements: The additional components and the condensation process may require more frequent maintenance.

What are Non-Condensing Tankless Water Heaters?

Non-condensing tankless water heaters are the more traditional design. They heat water directly without the additional step of capturing heat from exhaust gases. As a result, their efficiency ratings are usually lower than those of condensing models, typically around 80-85%. The exhaust gases are hotter, which requires specific venting arrangements to handle the higher temperatures.

Benefits of Non-Condensing Models:

  • Lower Initial Cost: These models are less expensive upfront, making them attractive for budget-conscious consumers.
  • Simplicity and Reliability: With fewer moving parts and a simpler design, non-condensing models can be more reliable and easier to maintain.


  • Lower Efficiency: Less efficient than condensing models, leading to potentially higher operating costs over time.
  • Venting Requirements: The need for special venting materials can increase installation costs and complexity.

Choosing Between Condensing and Non-Condensing

The choice between condensing and non-condensing tankless water heaters depends on several factors:

  • Budget: If initial cost is a primary concern, non-condensing models might be more appealing. However, for those willing to invest more upfront for lower operating costs, a condensing model is the way to go.
  • Installation Considerations: The location of installation and the feasibility of venting can influence the choice. Condensing models offer more flexibility with venting options.
  • Energy Savings Goals: For homeowners prioritizing energy efficiency and long-term savings, condensing water heaters offer significant advantages.


Both condensing and non-condensing tankless water heaters have their place in residential settings, offering unique benefits tailored to different homeowner needs and preferences. By understanding the distinctions between these two types, you can make a more informed decision that aligns with your budget, environmental values, and efficiency goals. Regardless of your choice, transitioning to a tankless water heater is a step forward in enjoying continuous hot water supply and energy savings.

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