Ao Smith Tankless Water Heaters Vs Navien Tankless Heater - A Pro'S

Choosing a new tankless water heater feels like a huge decision, doesn’t it? It’s a major investment in your home’s comfort and efficiency. You’ve probably spent hours researching, and two names keep popping up: A.O. Smith and Navien. It’s easy to feel stuck wondering which one is truly the right fit for your family and your budget.

I get it. As an HVACR technician, I’ve installed, serviced, and compared these units in countless homes. The good news is that you’re looking at two of the best brands in the business. But they are different, and the right choice for you isn’t always obvious.

I promise this guide will cut through the noise. We’re going to break down the ao smith tankless water heaters vs navien tankless heater debate, piece by piece, from a hands-on perspective. We’ll look at their core technology, efficiency, real-world performance, and long-term costs so you can make a confident, informed decision.

Meet the Contenders: A Quick Look at A.O. Smith and Navien

Before we dive into the technical details, let’s get to know the two brands standing in the ring. Think of them as two different types of champions, each with a unique history and approach to providing you with endless hot water.

A.O. Smith: The Established American Titan

A.O. Smith is a name that’s been synonymous with water heating for over a century. They are an American company with a rock-solid reputation built on durability and reliability. For many plumbers and technicians, A.O. Smith is the trusted, go-to brand they’ve worked with for decades.

Their strength lies in their vast product line, offering everything from traditional tank heaters to a wide range of tankless models. They provide both ultra-efficient condensing units and more budget-friendly non-condensing options, giving homeowners plenty of choices.

Navien: The Innovative Efficiency Leader

Navien, on the other hand, is the relative newcomer that shook up the industry. A South Korean company, they burst onto the North American scene with a laser focus on high-efficiency, condensing tankless technology. They quickly became leaders in innovation.

Navien is known for packing its units with advanced features, like built-in recirculation pumps for instant hot water and smart home connectivity. They are often the brand of choice for homeowners who prioritize cutting-edge technology and maximum energy savings.

The Core Technology Showdown: Condensing vs. Non-Condensing

The biggest difference between these two brands often comes down to the technology inside the box. Understanding this is the key to figuring out which unit makes more sense for your home and wallet. This is one of the most important ao smith tankless water heaters vs navien tankless heater tips I can offer.

Navien’s Signature: High-Efficiency Condensing Technology

Navien built its reputation on condensing technology. Here’s what that means in simple terms: a standard (non-condensing) water heater loses a lot of heat through its hot exhaust gas, which is vented outside.

A condensing unit, like every model Navien makes, has a second heat exchanger. It captures a significant amount of that escaping heat from the exhaust and uses it to preheat the cold water coming into the unit. This process is so effective that the exhaust gases are much cooler, allowing for venting with affordable, easy-to-install PVC pipe instead of expensive stainless steel.

The result? Higher efficiency, lower energy bills, and a more eco-friendly ao smith tankless water heaters vs navien tankless heater solution.

A.O. Smith’s Versatility: A Mix of Both Worlds

A.O. Smith offers a more diverse lineup. They have a full range of high-efficiency condensing models that compete directly with Navien. These units also use the two-heat-exchanger system and can be vented with PVC.

However, they also offer non-condensing models. These units are simpler in design and often have a lower upfront purchase price. The trade-off is that they are less efficient (typically around 82% vs. 95%+ for condensing) and require more expensive Category III stainless steel venting because their exhaust is much hotter.

AO Smith Tankless Water Heaters vs Navien Tankless Heater: A Head-to-Head Comparison

Alright, let’s put these two giants side-by-side and compare them on the factors that matter most to you as a homeowner. This detailed ao smith tankless water heaters vs navien tankless heater guide will cover everything from performance to price.

Energy Efficiency (UEF) and Long-Term Savings

The efficiency of a water heater is measured by its Uniform Energy Factor (UEF). The higher the number, the more efficient it is.

Navien: This is Navien’s home turf. Their entire NPE-2 series boasts very high UEF ratings, often 0.95 or higher. This means 95% of every dollar you spend on energy goes directly to heating your water. They are a top choice for a sustainable ao smith tankless water heaters vs navien tankless heater option.
A.O. Smith: Their condensing models in the ProLine XE and Signature Series are highly competitive, also achieving UEF ratings in the mid-90s. Their non-condensing models have lower UEF ratings, typically around 0.82.

Pro Tip: While a non-condensing unit is cheaper to buy, a condensing unit can save you hundreds of dollars on your energy bills over its lifespan, often paying back the initial price difference.

Flow Rate and Performance (GPM)

Flow rate, measured in Gallons Per Minute (GPM), tells you how much hot water the unit can produce at once. A higher GPM means you can run more fixtures (like a shower and a dishwasher) simultaneously.

Both A.O. Smith and Navien offer a wide range of models to suit homes of all sizes, from small condos to large houses with multiple bathrooms. Their flagship models can produce over 11 GPM, which is more than enough for most families.

A key advantage for Navien here is that many of their premium models (the NPE-A2 series) come with a built-in recirculation pump. This clever feature, called ComfortFlow®, slowly circulates hot water through your pipes, drastically reducing the wait time for hot water at the tap and saving thousands of gallons of water per year.

Installation and Venting Requirements

This is a huge factor in the total cost. Don’t worry, we’ll walk through how to ao smith tankless water heaters vs navien tankless heater installation choices are made.

Navien (and A.O. Smith Condensing): These units can be vented with PVC, CPVC, or polypropylene. This material is inexpensive and easy for a technician to work with, which can lower your total installation cost.
A.O. Smith Non-Condensing: These models must be vented with expensive, specialized Category III stainless steel. If you are replacing an old tank heater that was vented through the roof, the cost of running new stainless steel venting can add significantly to the project price.

Reliability and Common Problems

Both brands make reliable products, but they have different reputations when it comes to potential issues. Addressing common problems with ao smith tankless water heaters vs navien tankless heater is crucial for a fair comparison.

A.O. Smith’s non-condensing units are mechanically simpler, with fewer electronic components. This can sometimes translate to fewer potential points of failure over a long lifespan. They are built like tanks.

Navien units are more technologically advanced. While their modern units are very reliable, the added complexity of sensors, advanced control boards, and recirculation pumps means there are more components that could potentially fail. Early Navien models had some known issues, but the company has since addressed these, and their current NPE-2 line is considered very robust.

Crucial Takeaway: The single biggest factor in the reliability of any tankless water heater is the quality of the installation. An improper installation will cause problems, regardless of the brand.

The User Experience: Features, Controls, and Warranty

How you live with your water heater day-to-day also matters. Here’s how the two brands stack up in terms of usability and peace of mind.

Smart Features and Controls

Navien is the clear winner for the tech-savvy homeowner. Their NaviLink™ Wi-Fi remote control system allows you to monitor and adjust your water heater from your smartphone, change the water temperature, see diagnostics, and track energy usage. It’s a very polished and useful feature.

A.O. Smith is catching up and offers Wi-Fi on some of their high-end models, but it’s not as integrated across their entire product line as it is with Navien.

Warranty Comparison

Warranties are very competitive and quite similar between the two brands. You can generally expect:

Heat Exchanger: 15 years (the most important component)
Parts: 5 years
Labor: 1 year (typically from the installer)

Always confirm the specific warranty for the model you are considering, and remember that most manufacturers require the unit to be installed by a licensed professional for the warranty to be valid.

A Simple AO Smith vs. Navien Care Guide

Proper maintenance is key to a long, trouble-free life for your unit. The ao smith tankless water heaters vs navien tankless heater care guide is nearly identical for both brands’ condensing models.

Annual Flushing: Once a year, you need to flush the heat exchanger with a vinegar solution to remove mineral scale buildup (limescale). This is especially critical if you have hard water. You can hire a pro or buy a DIY flush kit.
Clean the Inlet Filter: Check and clean the small screen on the cold water inlet every 6-12 months to ensure good water flow.
Inspect the Venting: Periodically check the exterior vent terminations to make sure they are clear of debris, nests, or snow.

Following these ao smith tankless water heaters vs navien tankless heater best practices will ensure you get the best performance and lifespan from your investment.

The Final Verdict: Which Brand is Right for Your Home?

So, after all that, which one should you choose? There’s no single right answer, but we can make it simple. It all comes down to your priorities.

You should lean towards A.O. Smith if:

You are on a tighter budget and are considering a more affordable non-condensing model.
You value a brand with a very long history and a reputation for simple, rugged durability.
Your home’s layout makes installing stainless steel venting relatively straightforward.

You should lean towards Navien if:

Maximum energy efficiency and the lowest possible monthly energy bills are your top priority.
You want the latest technology, including smart home controls and a built-in recirculation system for instant hot water.
Your installation plan allows for easy and affordable PVC venting.

Frequently Asked Questions About AO Smith vs. Navien Tankless Heaters

How long do Navien and A.O. Smith tankless heaters last?

With proper professional installation and consistent annual maintenance (like descaling), both A.O. Smith and Navien tankless water heaters can be expected to last 20 years or even longer. This is significantly longer than the typical 8-12 year lifespan of a traditional tank-style heater.

Is a condensing tankless water heater always the better choice?

From an energy-saving and environmental perspective, yes. The benefits of a condensing unit almost always outweigh the higher initial cost over the life of the unit. However, in some rare retrofit situations where venting is extremely difficult and costly, a non-condensing unit might be a more practical, albeit less efficient, choice.

Can I install a tankless water heater myself?

I strongly advise against it. Installing a tankless water heater involves complex plumbing, gas line work (for natural gas or propane models), and electrical connections. A mistake can lead to dangerous gas leaks, carbon monoxide poisoning, or water damage. Furthermore, virtually all manufacturers will void the warranty if the unit is not installed by a licensed and certified professional.

Choosing between A.O. Smith and Navien is a great problem to have—you’re picking between two excellent options. By considering your budget, your desire for efficiency and tech features, and the specifics of your home’s layout, you can make a choice that will provide you with comfortable, reliable, and endless hot water for years to come.

Take your time, get quotes from qualified local pros, and you’ll be enjoying that new tankless water heater in no time. Stay comfortable!

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David Clark

Founder & Lead HVAC Specialist at HVACRLY

David Clark is the founder of HVACrly and a certified HVAC specialist with 10+ years working on residential and light-commercial systems. He turns complex heating, cooling, ventilation, and refrigeration topics into clear, actionable guides focused on safety and energy efficiency. When he’s not on a service call, he’s testing tools and writing step-by-step tutorials.