Which Is Better Condensing or Non Condensing Tankless Water Heaters?

Are you tired of running out of hot water during your morning shower or feeling overwhelmed by the choices of tankless water heaters on the market? Fear not, my friend! I’m here to help you navigate the world of condensing and non-condensing tankless water heaters, so you can make an informed decision and find the perfect solution for your home. In this blog post, we’ll dive deep into the pros and cons of both types, as well as explore some key factors to consider when making your choice. So, let’s get started and find the ideal tankless water heater for you!

Keynote: Which Is Better Condensing or Non Condensing Tankless Water Heaters?

Condensing tankless water heaters are generally more energy-efficient and eco-friendly than non-condensing units. However, they tend to be pricier upfront. Choose condensing for long-term savings and environmental benefits, but opt for non-condensing if upfront cost is a primary concern.

How Condensing and Non-Condensing Tankless Water Heaters Work

Condensing Tankless Water Heaters

Basic principles:

Condensing tankless water heaters are an advanced version of the traditional tankless water heaters. They work by heating water on-demand, meaning they only heat the water when you need it. This is done by using a gas burner or an electric element to heat the water as it passes through a heat exchanger.

Heat exchanger and efficiency:

The main difference between condensing and non-condensing units is the heat exchanger. In condensing models, there are two heat exchangers: a primary one that initially heats the water and a secondary one that captures and reuses the residual heat from the exhaust gases. This process allows condensing tankless water heaters to achieve a higher efficiency, often reaching up to 98%.

Non-Condensing Tankless Water Heaters

Basic principles:

Non-condensing tankless water heaters also heat water on-demand, but they use a single heat exchanger. As the water passes through the heat exchanger, it’s heated by a gas burner or electric element, providing you with hot water instantly.

Heat exchanger and efficiency:

The efficiency of non-condensing tankless water heaters is slightly lower than their condensing counterparts. This is because they only use a single heat exchanger and don’t capture the residual heat from the exhaust gases. Typically, non-condensing units have an efficiency of around 80-85%.

Comparison Table: Condensing vs. Non-Condensing

Basic PrincipleHeats water on-demandHeats water on-demand
Heat ExchangerTwo heat exchangers (primary and secondary)Single heat exchanger
EfficiencyUp to 98%80-85%

Energy Efficiency

Efficiency ratings measure the percentage of energy used by a water heater that is actually converted into heat. The higher the efficiency rating, the more energy-efficient the appliance is. This is important because it directly affects your energy bills and the environmental impact of your water heating system.

Comparing condensing and non-condensing efficiency

As mentioned earlier, condensing tankless water heaters have an efficiency of up to 98%, while non-condensing units typically have an efficiency of 80-85%. To put this into perspective, let’s say you spend $1,000 per year on energy to heat water with a non-condensing tankless heater. With a condensing unit, you could potentially save up to $180 per year, as you’d only be spending around $820 on energy for the same amount of hot water.

Energy savings

The initial investment for a condensing tankless water heater is often higher than a non-condensing unit. However, considering the potential energy savings over time, a condensing unit can be more cost-effective in the long run. These savings can be especially significant if you live in a region with high energy costs.

Using a more energy-efficient water heater not only saves you money but also reduces your carbon footprint. By consuming less energy, you contribute to fewer greenhouse gas emissions, making a positive impact on the environment.

Bullet list: Key factors affecting efficiency

  • Size and capacity of the water heater
  • Fuel type (natural gas, propane, or electricity)
  • Climate and ambient temperature
  • Proper installation and maintenance
  • Usage patterns and hot water demand

Installation and Maintenance

Installation requirements

Condensing tankless water heaters require a PVC vent for exhaust gases, which is typically more affordable and easier to install than the stainless steel venting needed for non-condensing units. This is because condensing heaters produce cooler exhaust gases, reducing the risk of damage to the venting materials.

Both types of tankless water heaters require adequate space for installation, but condensing units generally have a more compact design. This can be beneficial if you have limited space available. Additionally, it’s essential to consider factors such as access to gas or electricity, proper ventilation, and adherence to local building codes when selecting a location for installation.

Maintenance and service

Condensing tankless water heaters generally require less frequent cleaning and servicing compared to non-condensing units. This is because the secondary heat exchanger in condensing models helps reduce mineral build-up. However, regular maintenance is still necessary for both types to ensure optimal performance and a longer lifespan.

Common issues that may arise with both types of tankless water heaters include mineral build-up, ignition problems, and venting issues. Regular maintenance, such as descaling the heat exchanger and inspecting the venting system, can help prevent and address these problems.

Comparison Table: Installation and Maintenance

VentingPVC venting (cooler exhaust gases)Stainless steel venting (hotter exhaust gases)
Space and location considerationsMore compact designLarger design
Cleaning and servicing frequencyLess frequentMore frequent

Costs and ROI

a. Initial costs

Condensing tankless water heaters typically have a higher purchase price compared to non-condensing units. This is due to their advanced technology and higher efficiency.

Installation costs for condensing tankless water heaters can be lower than non-condensing units, as they require more affordable PVC venting materials. However, the overall cost will depend on factors such as the complexity of the installation and local labor rates.

b. Operating costs

As discussed earlier, condensing tankless water heaters are more energy-efficient, resulting in lower energy consumption and, consequently, lower energy bills.

Maintenance costs for condensing units tend to be lower due to their reduced cleaning and servicing frequency. However, both types require regular maintenance to ensure optimal performance and longevity.

c. Return on investment (ROI)

The break-even point for a condensing tankless water heater may take longer to reach due to its higher initial costs. However, the energy savings and lower maintenance costs can contribute to a quicker ROI.

Over time, the energy savings and reduced maintenance costs of a condensing tankless water heater can outweigh its higher initial costs, making it a more cost-effective option in the long run.

Bullet list: Key factors affecting costs and ROI

  • Purchase price
  • Installation costs
  • Energy efficiency
  • Maintenance costs and frequency
  • Local energy rates
  • Usage patterns and hot water demand

Pros and Cons

Condensing tankless water heaters


  • Higher energy efficiency (up to 98%)
  • Lower energy bills
  • Reduced greenhouse gas emissions
  • More compact design
  • Lower maintenance frequency
  • Cooler exhaust gases, allowing for more affordable PVC venting


  • Higher initial purchase price
  • More complex technology, which may require specialized service

Non-condensing tankless water heaters


  • Lower initial purchase price
  • Proven and reliable technology
  • Easier to find replacement parts and service


  • Lower energy efficiency (80-85%)
  • Higher energy consumption
  • Higher maintenance frequency
  • Hotter exhaust gases, requiring more expensive stainless steel venting

Bullet list: Pros and Cons

Condensing Tankless Water Heaters:

  • Pros: High energy efficiency, lower energy bills, compact design, lower maintenance frequency, affordable venting
  • Cons: Higher initial purchase price, more complex technology

Non-Condensing Tankless Water Heaters:

  • Pros: Lower initial purchase price, proven technology, easier to find parts and service
  • Cons: Lower energy efficiency, higher energy consumption, higher maintenance frequency, more expensive venting

Final Thought

Ultimately, the choice between a condensing and a non-condensing tankless water heater will depend on your unique circumstances, priorities, and budget. While condensing units boast superior energy efficiency and lower long-term costs, non-condensing heaters offer a more affordable upfront investment and time-tested reliability. It’s essential to consider not only the financial aspects but also the environmental impact of your decision.

Remember, investing in a more efficient water heater is not only a wise financial move, but it’s also a step towards a greener, more sustainable future for you and the planet. So, take a moment to reflect on your needs and values, and make a choice that warms your heart (and your water) for years to come.

Condensing or Non Condensing Tankless Water Heaters (FAQs)

Does a condensing tankless water heater need a drain?

Yes, a condensing tankless water heater requires a drain to dispose of the condensate produced during the heating process. The condensate is created when vapor in the exhaust gases cools and turns into liquid, which needs to be safely drained away to prevent corrosion and damage to the unit.

Is condensing tankless worth it?

A condensing tankless water heater can be worth the investment due to its higher energy efficiency compared to non-condensing models. The second heat exchanger in condensing units captures additional heat from the exhaust gases, resulting in less energy waste and lower operating costs.

What are the best brands for non-condensing tankless water heaters?

Some of the best brands for non-condensing tankless water heaters include Rinnai, Navien, and Rheem. These manufacturers offer reliable and efficient units with solid warranties, making them popular choices for homeowners seeking endless hot water.

What is the lifespan of a non-condensing tankless water heater?

The lifespan of a non-condensing tankless water heater typically ranges from 10 to 15 years, with proper maintenance. Factors such as water quality and usage patterns can affect the longevity of the primary heat exchanger and other components.

How much money can I expect to save on my energy bills by switching to a condensing tankless water heater?

Switching to a condensing tankless water heater can save you up to 15-20% on your energy bills compared to traditional tank-based systems. The exact savings depend on factors like usage patterns, local energy costs, and the efficiency of your current water heating system.

Are there any DIY repairs I can make to my non-condensing tankless water heater?

Some common DIY repairs for non-condensing tankless water heaters include descaling the heat exchanger, cleaning the water filter, and checking the electrical connections. However, more complex issues should be addressed by a professional technician to maintain the warranty and ensure safe operation.

What are some eco-friendly alternatives to traditional water heaters?

Eco-friendly alternatives to traditional water heaters include solar water heaters, heat pump water heaters, and electric tankless water heaters. These options reduce greenhouse gas emissions and can be more energy-efficient, helping to lower your environmental footprint.

Can a condensing tankless water heater be installed outside?

Yes, a condensing tankless water heater can be installed outside, provided it’s designed for outdoor use and meets local building codes. Outdoor installation saves indoor space and eliminates the need for venting, but it’s essential to protect the unit from weather-related damage.

What are some common problems with tankless water heaters and how can I avoid them?

Common problems with tankless water heaters include fluctuating water temperatures, limited hot water supply, and mineral buildup. To avoid these issues, ensure proper sizing of the unit (considering gallons per minute, or GPM), regular maintenance, and installation of a water softener if your water supply is hard.

Are there any environmental concerns associated with using a tankless water heater?

While tankless water heaters are generally more energy-efficient than traditional tank-based systems, they still produce greenhouse gas emissions if they run on natural gas or propane. Choosing electric tankless water heaters or other eco-friendly alternatives can help reduce the environmental impact.

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