Condensing vs Non-Condensing Boiler: Which Is Better? - Navien

28 Jul.,2025

 

Condensing vs Non-Condensing Boiler: Which Is Better? - Navien

If you’re considering a heating boiler for your home or business, you might wonder what the differences are between condensing and non-condensing models, and which type is best for your project. This article will summarize the key differences so you can feel confident choosing the right model.

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Non-condensing boilers have been around longer than condensing boilers, which entered the market in the s. Condensing boilers have more advanced technology, which leads to differences in operation, installation requirements and energy efficiency.

Condensing vs Non-Condensing Boilers: How They Work

Condensing and non-condensing gas heating boilers both use natural gas (or liquid propane) as a fuel source, and provide reliable hydronic heating (via radiators, baseboards, or radiant floor heating systems).

Non-condensing boilers (aka conventional or traditional boilers) are larger and heavier than condensing boilers, and are typically floor-standing. Non-condensing boilers burn gas to heat water which in turn heats your home. The combustion exhaust is extremely hot and must be directly vented via a chimney or flue.

Condensing boilers (aka high efficiency boilers) are smaller and lighter, and typically wall-mounted. Condensing boilers use a heat exchanger to capture and recycle heat from the exhaust gas before it’s vented. This makes the heating process more energy efficient, lowers the exhaust gas temperature, and creates condensation inside the unit that needs to be drained.

Installation Differences

Non-condensing boilers must be vented using a proper chimney or flue due to the extremely high temperatures of the exhaust gas. Condensing boilers have cooler exhaust gas (because the heat is recycled) and can be vented using a wider range of materials including PVC and polypropylene. In addition, Navien condensing boilers allow 2” venting up to 65’ and 3” venting up to 150 feet, giving you more installation location flexibility.

Condensing boilers require a drain line for the acidic condensate liquid, which could potentially limit installation locations. Non-condensing boilers don’t need a drain because the exhaust gas doesn’t condense inside the unit.

No matter what type of residential gas boiler you choose, installation costs can vary based on the home and boiler size, number of zones, and how much work needs to be done for gas piping and venting. Find an authorized Navien installer to get a quote for boiler installation.

Efficiency Differences

Condensing boilers consume less fuel than non-condensing boilers, which means lower gas utility bills and a smaller carbon footprint. Navien condensing gas boilers have an AFUE of up to 95% and are Energy Star certified.

In comparison, traditional boilers have an AFUE of up to 80%. This means that up to 80% of the fuel is used to heat your home, while up to 20% is lost through inefficiencies. Replacing an older non-condensing heating boiler with a Navien high-efficiency condensing boiler can significantly reduce your monthly home heating bills.

Maintenance & Lifespan

Both condensing and non-condensing boilers can have a service life of around 15-20 years. How long your heating boiler lasts depends on how well the boiler was installed, climate and usage patterns, and how well you keep up with recommended maintenance.

All residential boilers should be inspected and serviced annually by a professional. Both condensing and non-condensing boilers should have the heat exchanger flushed once a year or as determined by combustion efficiency.

If you live in a region with hard water, using a scale prevention system with your heating boiler can extend its service life by preventing damaging lime and calcium deposits.

Which Type of Boiler Is Better for Your Home?

To decide whether a condensing or non-condensing boiler is the best choice for your home, you’ll need to consider:

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Installation options

  • If you have an existing chimney or flue that can accommodate high-temperature exhaust, but you don’t have an install location with available drainage, then non-condensing makes the most sense for your application.
  • If you do have an installation location with available drainage, then you can benefit from a condensing boiler’s more efficient home heating in a smaller package.

Energy efficiency

  • If you want lower utility bills and a smaller carbon footprint, a condensing boiler is the best choice.

Domestic hot water

  • If you want one unit to provide both home heating and domestic hot water, you should consider a combi-boiler.

Learn More:

Boilers 101 video

Navien residential condensing boilers

Navien commercial condensing boilers

Condensing vs non-condensing tankless water heaters

Environmental Benefits of Wall-Mounted Condensing Boilers - Ecostar

Environmental Benefits of Wall-Mounted Condensing Boilers

Energy consumption and eco-friendly solutions are of critical importance today for both individuals and businesses. Especially in the heating sector, environmental concerns and rising energy costs have increased interest in more efficient and sustainable technologies. In this regard, wall-mounted condensing boilers stand out as technologies that provide energy savings while causing less harm to the environment. So, how do these boilers work, and what are their environmental benefits?

What is a Wall-Mounted Condensing Boiler?

A wall-mounted condensing boiler is a heating system that, in addition to using the heat generated by the combustion of natural gas, also utilizes the extra energy obtained by condensing the water vapor in the combustion gases. Unlike traditional boilers, they recover extra heat energy by re-condensing the water vapor in exhaust gases. This allows them to consume less fuel while producing more heat, thereby improving energy efficiency.

Are Condensing Boilers Environmentally Friendly?

Yes, condensing boilers are considered eco-friendly systems. The main reason for this is their ability to significantly reduce carbon emissions. CO2 emissions from the combustion of fossil fuels have negative environmental impacts. However, condensing boilers produce lower carbon emissions due to their reduced fuel consumption. Especially those running on natural gas, a cleaner energy source compared to other fossil fuels, help reduce the negative environmental impacts.

Can You Reduce Your Carbon Footprint with Wall-Mounted Condensing Boilers?

One of the most effective ways to reduce your carbon footprint is by using energy-efficient devices like condensing boilers. These boilers consume less fuel per unit thanks to their high energy efficiency, which means lower CO2 emissions. Providing high efficiency in a compact space, they not only reduce energy costs but also minimize environmental damage. For this reason, condensing boilers play a crucial role in transitioning to a sustainable lifestyle.

How to Achieve Energy Efficiency and Save on Natural Gas Consumption?

One of the biggest advantages of condensing boilers is their much higher energy efficiency compared to traditional boilers. The additional energy obtained from condensing water vapor can result in an efficiency of over 100%. As a result, energy consumption is significantly reduced, and natural gas consumption is minimized. Condensing boilers optimize gas pressure and combustion air, ensuring maximum efficiency. This provides both economic savings and environmental protection.

How Can I Lower My Energy Costs with Wall-Mounted Condensing Boilers?

Wall-mounted condensing boilers offer several strategies for reducing energy costs:

  • Regular Maintenance: By regularly maintaining your boiler, you can extend its lifespan and preserve its energy efficiency. A well-maintained condensing boiler consumes less fuel, thereby reducing energy costs.
  • Using a Smart Thermostat: Condensing boilers can optimize energy consumption when integrated with smart thermostats. By adjusting the working hours of the boiler based on heating needs, you can prevent unnecessary energy consumption.

What are the Long-Term Environmental Advantages of Condensing Boilers?

Condensing boilers not only provide energy savings in the short term but also minimize environmental impacts in the long term. In today's world, where fossil fuels are depleting, energy costs and environmental concerns are the main factors driving the development of heating systems. Condensing boilers, by reducing the consumption of natural resources with their high energy efficiency, have been proven to lower long-term energy costs and contribute to environmental protection.

What is the Environmental Contribution of Wall-Mounted Condensing Boilers?

In conclusion, wall-mounted condensing boilers play a significant role in contributing to the environment with their energy efficiency and low carbon emissions. These boilers are an excellent solution for those looking to reduce both energy costs and environmental impacts. Condensing boiler technology will continue to be an important part of the heating sector in the future, contributing to environmental sustainability.

For more wall mounted condensing gas boilerinformation, please contact us. We will provide professional answers.