Navien 210S Vs 210 A Tankless Water Heater – The Definitive

ByDavid Clark

Shopping for a new tankless water heater can feel like you’re trying to decipher a secret code. You see two models, the Navien NPE-210S and the NPE-210A, and they look nearly identical. They have the same BTU rating, the same sleek white box… so what’s the real difference, and which one is right for your home?

I hear this question all the time from homeowners, and it’s a great one. Choosing incorrectly can mean either overspending on features you don’t need or missing out on the one feature that would have made all the difference in your daily comfort.

Don’t worry, we’re going to clear up all the confusion today. I promise this guide will give you a clear, no-jargon breakdown of the navien 210s vs 210 a tankless water heater comparison. We’ll walk through exactly what those ‘S’ and ‘A’ letters mean, how their technology impacts your access to hot water, and which model will be the best investment for your family’s needs.

Let’s dive in and get you that endless, on-demand hot water you’ve been dreaming of.

Meet the Contenders: The Navien NPE-2 Series at a Glance

Before we get into the nitty-gritty differences, let’s talk about what makes both the NPE-210S and NPE-210A fantastic choices. These are part of Navien’s NPE-2 series, which are high-efficiency, condensing tankless water heaters. This is top-tier technology.

Here’s what they both share:

  • High Efficiency: Both units boast an impressive Uniform Energy Factor (UEF) of 0.96. This means 96% of the fuel they burn is converted directly into heat for your water, saving you a significant amount on your energy bills compared to a traditional tank heater. This is a core part of what makes them an eco-friendly navien 210s vs 210 a tankless water heater choice.
  • Condensing Technology: They use a secondary heat exchanger to capture extra heat from the exhaust gases that would normally be wasted. This is the secret to their high efficiency.
  • Max BTU Input: Both are rated for 180,000 BTU/h, providing a strong flow rate suitable for homes with 2-3 bathrooms.
  • Flexible Venting: They can be vented with standard 2″ PVC, CPVC, or polypropylene, which can significantly reduce installation costs.
  • Wi-Fi Ready: Both units are compatible with Navien’s NaviLink Wi-Fi remote control system (sold separately), allowing you to control temperatures and get diagnostics right from your smartphone.

On paper, they look like twins. But the real story, and the reason for the price difference, lies in one key area: hot water recirculation.

The Core Difference: How They Deliver Instant Hot Water

The single biggest distinction between the ‘S’ (Standard) and ‘A’ (Advanced) models is how they handle hot water recirculation. Recirculation is the technology that eliminates the wait for hot water at your faucet or showerhead.

Think about it: in a standard plumbing setup, the hot water left in the pipes after you last used it cools down. When you turn on the tap again, you have to run the water and push all that cold water out until the hot water arrives from the heater. Recirculation solves this by creating a loop that keeps hot water readily available.

This is where our two models diverge. This section of our navien 210s vs 210 a tankless water heater guide will break it down.

How the NPE-210S (Standard) Handles Recirculation

The NPE-210S is capable of recirculation, but it requires an external recirculation pump and loop. This means your home must either have a dedicated return line plumbed from the furthest fixture back to the water heater, or you’ll need to install one.

You then purchase and install an external pump that pushes the water through this loop. The water heater’s internal controls can manage this external pump, but the key takeaway is that the pump is not part of the unit itself.

Choose the NPE-210S if:

  • Your home is already plumbed with a dedicated recirculation line.
  • You are doing a major renovation and can easily add a dedicated return line.
  • You prefer to use a specific brand or type of external pump.

How the NPE-210A (Advanced) Elevates Recirculation

The NPE-210A is the all-in-one solution. The ‘A’ stands for Advanced, and it lives up to the name by including a built-in recirculation pump AND a mini buffer tank right inside the unit. This is a game-changer for most homes.

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This internal pump gives you two powerful recirculation options:

  1. Internal Recirculation: It can use your existing dedicated return line, just like the ‘S’ model, but without the need to buy and install an external pump.
  2. NaviCirc™ Technology: This is the magic. For homes without a dedicated return line, you can use the NaviCirc valve. This small valve is installed under the sink at the furthest fixture. It uses your existing cold water line as a temporary return path for the hot water. The built-in pump in the 210A pushes hot water to the valve, which then sends the now-cool water back to the heater through the cold line.

The built-in buffer tank is another huge benefit. It holds a small amount of heated water, which helps eliminate the “cold water sandwich” effect—that brief burst of cold water you sometimes get with other tankless heaters. This provides a smoother, more consistent hot water experience.

A Head-to-Head Feature Breakdown: Navien 210S vs 210A Tankless Water Heater

Let’s put the key features side-by-side for a quick comparison. Remember, most performance specs are identical—the value is in the built-in components.

| Feature | Navien NPE-210S (Standard) | Navien NPE-210A (Advanced) | |—|—|—| |

Recirculation Pump

| External (must be purchased separately) |

Internal (built-in)

| |

Buffer Tank

| No |

Yes (built-in)

| |

NaviCirc™ Compatible

| No |

Yes (for homes without a return line)

| |

Installation Complexity

| Requires plumbing for an external pump | Simpler installation, especially with NaviCirc™ | |

Upfront Cost

| Lower | Higher | |

Best For

| Homes with existing dedicated return lines | Homes without a return line, or for a simpler all-in-one installation |

One of the most important navien 210s vs 210 a tankless water heater tips I can offer is this: the slightly higher cost of the ‘A’ model is often completely offset by not having to buy an external pump or pay for the complex labor of installing a dedicated return line.

Installation and Plumbing: What Your Technician Needs to Know

From a technician’s perspective, the installation process is where you really see the difference. While both units require a licensed professional for safe and warrantied installation, the ‘A’ model simplifies things considerably.

With the NPE-210A, we connect the water lines, gas line, and venting, and the recirculation system is ready to go. If using NaviCirc™, we just need to install the small valve under a sink, which is a quick and easy job. This saves time and potential points of failure.

With the NPE-210S, the installation involves more steps. We have to source a compatible external pump, find a suitable location to mount it near the heater, and plumb it into the system. This adds labor time and material costs to the overall project.

Considering the long-term benefits of a sustainable navien 210s vs 210 a tankless water heater, the integrated design of the 210A often leads to a cleaner, more reliable setup with fewer external components to worry about down the line.

Which Model is Right for Your Home? A Practical Decision Guide

Okay, let’s bring it all home. Here’s a simple checklist to help you decide. This is the core of our navien 210s vs 210 a tankless water heater best practices for selection.

You should choose the Navien NPE-210S if…

  • You are certain your home already has a dedicated hot water return line running from your furthest bathroom back to the water heater location.
  • You are replacing an old tank heater that was part of a recirculation system with an external pump that is still in good working order.
  • You are on a very tight upfront budget and can live without recirculation for now, knowing you can add an external pump later.

You should choose the Navien NPE-210A if…

  • You want instant hot water but your home does not have a dedicated return line. The NaviCirc™ feature is designed exactly for you.
  • You want the simplest, most integrated solution with fewer external parts to maintain or fail.
  • You want to eliminate the “cold water sandwich” effect for the most comfortable and consistent hot water delivery.
  • You value the convenience of an all-in-one package and want to minimize installation time and complexity. For most homeowners, this is the superior choice.
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Long-Term Care and Common Problems

Regardless of which model you choose, proper maintenance is key to a long and efficient service life. Here is a brief navien 210s vs 210 a tankless water heater care guide to keep your unit running smoothly.

Annual Descaling: The biggest enemy of any tankless water heater is mineral scale buildup (lime and calcium). You should have your unit professionally descaled once a year, or more often if you have very hard water. This involves circulating a vinegar or other descaling solution through the heat exchanger to dissolve buildup.

Check the Inlet Filter: Both models have a small filter screen on the cold water inlet. It’s a good idea to check and clean this every 6 months. Simply turn off the water to the unit, unscrew the inlet connection, and rinse the small screen. This is one of the few DIY-friendly tasks.

Common Error Codes: One of the most common problems with any tankless heater is an error code related to flame failure (like Navien’s Error Code E012). This can be caused by gas pressure issues, ignition problems, or a blocked intake/exhaust vent. This is not a DIY fix. If you see persistent error codes, it’s time to call a certified technician.

Frequently Asked Questions About Navien 210S vs 210A Models

What is the flow rate of the Navien NPE-210S and 210A?

Both models have the same performance. They can produce up to 10.1 gallons per minute (GPM) with a 35°F temperature rise. In colder climates where your incoming water is colder (requiring a 77°F rise), they produce a still-strong 4.5 GPM, enough to run two showers and a sink simultaneously.

Does the NPE-210A’s recirculation pump use a lot of electricity?

No, it’s very efficient. The ‘A’ model has an intelligent preheating function that can learn your hot water usage patterns. This means the pump only runs when it anticipates you’ll need hot water, rather than running 24/7. This saves a significant amount of energy.

Can I install a Navien tankless water heater myself?

As an HVACR professional, I strongly advise against it. Installation involves working with gas lines, water plumbing, and high-voltage electricity. A professional installation is required to ensure safety, proper performance, and to keep your manufacturer’s warranty valid.

What is the warranty on the Navien NPE-2 series?

Navien offers a very strong warranty. It typically includes 15 years on the heat exchangers, 5 years on other parts, and 1 year on labor when installed by a certified professional. Always confirm the latest warranty details at the time of purchase.

Ultimately, the debate between the navien 210s vs 210 a tankless water heater comes down to your home’s specific plumbing and your desire for convenience. The NPE-210A, with its built-in pump and buffer tank, represents the most advanced, convenient, and user-friendly technology for the vast majority of homeowners.

While the NPE-210S is a fantastic, high-efficiency unit, its ideal use case is more niche. By investing a little more upfront in the ‘A’ model, most people get a superior hot water experience and a simpler, more cost-effective installation. Making the right choice here will bring you years of reliable, endless, and energy-efficient hot water.

Stay comfortable out there!

David Clark
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