Best Condensing Tankless Water Heater Review (2021 Edition)

Last Updated On October 18, 2021
the best condensing tankless water heater

You have two choices when it comes to tankless water heaters for your home: condensing and non-condensing. What causes some people to consider purchasing a condensing tankless water heater unit? Let’s explore your options, and discuss the differences.

Non-condensing units vent the heat generated by the water heater outside while condensing water heaters absorb the heat, and then use it to help heat the water. Today, we’ll be focusing on condensing units to help you decide what is best for your situation. 

This PlumbingNav review will cover the top 3 best condensing tankless water heaters and provide information to help you determine which one is right for you. 

What's In This Guide?

      Top Sellers: Our Favorite Condensing Units:  

      In a hurry, and just want to see our top picks in summary? Here are the top 3, below. 

      1. Rinnai SE+ Series RU130iN Condensing Tankless Water Heater (Our Top Pick)
      2. Noritz NRC661 Direct Vent Condensing (Best Budget)
      3. Rheem RTGH (Best High End)

      ImageProduct
      digital-business-prep-table__image
      Rinnai SE+ Series RU130iN
      • Produces hot water at a rate of 7 GPM
      • Rating of .93UEF
      • Advanced technology
      • Produces hot water at a rate of 7 GPM
      • Rating of .93UEF
      • Advanced technology
      View on Amazon
      digital-business-prep-table__image
      Noritz NRC66DVNG Indoor Condensing Direct
      • Low NOx burner
      • 12 year eat exchange warranty
      • 93% thermal efficiency
      • Low NOx burner
      • 12 year eat exchange warranty
      • 93% thermal efficiency
      View on Amazon
      digital-business-prep-table__image
      Rheem 694900 Professional Prestige Series
      • .93 UEF efficiency rating
      • 8.4 GPM flow rate
      • WiFi and Bluetooth connectivity
      • .93 UEF efficiency rating
      • 8.4 GPM flow rate
      • WiFi and Bluetooth connectivity
      View on Amazon

      Our Rating On the Best Condensing Tankless Water Heater

      Rinnai SE+ Series RU130iN Condensing Tankless Water Heater 

      The Rinnai SE+ series natural gas, condensing, tankless water heater provides plenty of hot water to up to 7 fixtures simultaneously at top efficiency with an efficiency rating of .93 UEF. The unit also comes fully equipped with the latest technology, including a mobile app and WiFi connectivity. You can see why we love this one.

      A condensing tankless water heater may not provide an immediate return on your investment. However, in time, the smaller utility bills will pay off the difference. Most people feel this makes condensing tankless water heaters worth the upfront investment. You should only make the upgrade if you plan to stay in your current home for an extended period of time.

      What Are The Advantages and Disadvantages of a Condensing Tankless Water Heater?

      There are a lot of benefits to condensing tankless water heaters that make them quite an attractive choice. But, of course, the benefits come with one or two drawbacks as well. Here are the advantages and disadvantages of condensing tankless water heaters. 

      Advantages: 

      • Higher Efficiency

      Since condensing units absorb the heat and use it to help heat the water, it makes the product more efficient in how it works. In general, condensing tankless water heaters provide 90% efficiency while non-condensing units only reach about 80% efficiency. 

      This means lower utility bills. In fact, a family of 4 can save up to $95 a year with an EnergyStar certified condensing gas tankless water heater

      • Inexpensive Ventilation Materials

      Condensing tankless water heaters absorb heat before exhausting it, cooling it down first. This means that you can use standard plastic PVC pipes instead of high-end pipes designed to stand up to high temperatures. This will save you money on installation. 

      • Advanced Technology

      The condensing process during water heating is the more advanced method, making it the way of the future. Most people want to buy the product with the latest in water heater technology so that it holds up for as long as possible. Longevity is a key factor, so buying a unit that uses condensing technology will bring value for years to come.

      Disadvantages: 

      • Possible Corrosion

      The condensation created from a condensing tankless water heater once the temperature of the gases falls below dew point can lead to corrosion unless the product uses high-end Category-3 stainless steel. The acidity of the condensation will eat at copper pipes, over time.

      • Higher Initial Investment 

      Condensed units usually cost more than similar non-condensing options. However, you will make up for the higher initial investment in lower utility bills. 

      • More Maintenance Required

      Condensing tankless water heaters requires some additional maintenance compared to non-condensing options. Since the product creates condensation, you will need to get rid of the moisture from time to time to avoid water damage.

      What Are The Key Features Of Condensing Tankless Water Heaters?

      The key feature of a condensing tankless water heater is the second heat exchanger. This second heat exchanger uses heat it captures from the flue gases and heats incoming water before sending it to the primary heat exchanger.

      This means the primary heat exchanger doesn’t need to work so hard. Since the heat from the gas is repurposed to heat the water, the gas cools off before the unit vents it. 

      Our Review of the Best Condensing Tankless Water Heater

      Our pick for the best condensing tankless water heater is the Rinnai RU130iN Tankless Gas Water Heater. We will cover the product in detail and compare it to some of the other top products on the market. 

      Rinnai SE+ Series RU130iN Condensing Tankless Water Heater

      The Rinnai RU13iN direct-vent condensing tankless water heater will supply endless hot water to your home at a rate of 7 GPM, more than enough for a family of 4 – 5. As one of Rinnai’s Sensei SE+ super high-efficiency series, you can trust the product to lower your utility bills with an efficiency rating of .93 UEF. 

      We love how you can control your water heater from anywhere with the convenient Rinnai mobile app, or use voice control technology. The Circ-Logic recirculation technology to learn your unique water heating patterns and adjust to them automatically. 

      You can also rest assured knowing your new unit will work as expected or better as part of the reputable Rinnai brand of products, but it comes with an impressive warranty to cover the unexpected. 

      Pros

      • Produces hot water at a rate of 7 GPM
      • Part of the “super-high efficiency” series with a rating of .93UEF
      • Advanced technology

      Cons

      • Expensive 
      • Indoor installation only
      • No conversion kit

      Reputable Company/Customer Service:

      Rinnai established themselves as a leader in condensing tankless water heaters with their dedication to quality products that exceed expectations. Call customer service to answer all of your questions and troubleshoot with you if something goes wrong. 

      Read this post where we review all of the best selling Rinnai tankless water heaters.

      Manufacturing Process:

      Rinnai is a Japanese country with manufacturing plants scattered throughout the world, including:

      • Canada
      • Australia
      • China
      • Hong Kong
      • Malaysia
      • New Zealand
      • Indonesia
      • Italy
      • Singapore
      • Thailand
      • Vietnam 

      Distributors supply the products to qualified sellers who then get them into your home. 

      Ease of Use:

      Rinnai makes all their products as simple to use as possible. This condensing water heating unit comes with a control panel that provides a clear digital display of the water heater’s current temperature setting. You can use the buttons on the control panel to turn the item on and off as well as change the temperature. 

      Rinnai makes controlling your water heater even easier by allowing you to connect to the WiFi in your home and use voice controls. You can also download an app on your smartphone that gives you the ability to control the device and receive critical notifications from anywhere. 

      Safety Issues:

      Rinnai includes several safety features to ensure protection, including a default max setting of 120° F to prevent scalding. However, you can turn the temperature up to 140° F with some simple alterations. 

      Also, the fan continues to blow after you turn the hot water off to exhaust any pent-up gas. 

      Overall Effectiveness:

      You can depend on this water heater to work properly at all times, and you can expect it to work for up to 20 years

      How Does it Compare Against Competitors?

      Rinnai faces some good competition, and it’s good to know what advantages and disadvantages it has to some other condensing tankless water heaters out there. 

       Rinnai SE+ Series VS. Noritz NRC661 

      Noritz NRC661 Direct-vent Condensing Tankless Water Heater

      The Noritz NRC661 direct-vent condensing tankless water heater holds up quite nicely to the Rinnai SE+ series, making it a quite popular option. It provides water at a speed of 6.6 GPM with 93% thermal efficiency and an efficiency rating of .91 UEF and direct electronic ignition. 

      Pros

      • Low NOx burner
      • 12 year eat exchange warranty
      • 93% thermal efficiency

      Cons

      • No WiFi or Bluetooth connectivity options
      • Valve kit sold separately
      • Exhaust must be a minimum of 8” from door or window

      The main differences between the Rinnai SE+ series and the Noritz NRC661 are:

      • Efficiency- Our Rinnai pick wins with a .93 UEF rating, but the Noritz model comes close with a .91 UEF rating. 
      • Hot Water Generation – The Rinnai model beats the Noritz with 7 GPM compared to the very respectable 6.6 GPM. 
      • User Friendliness – Rinnai overshadows Noritz in this area with the simple control panels and advanced technology features. 
      • Cost – The Noritz model costs significantly less, making it more appropriate for people on a budget.
      • Size – The Noritz model is significantly smaller at 11.42 pounds than the Rinnai model, with 62 pounds. 

      Rinnai SE+ Series VS. Rheem RTGH

      Click To Check Price

      Rheem RTGH

      The Rheem RTGH direct-vent condensing tankless water heater provides another great option on the market by yet another respected name in the industry. It generates water at a speed of 8.4 GPM and .93 energy efficiency rating.

      Pros

      • .93 UEF efficiency rating
      • 8.4 GPM flow rate
      • WiFi and Bluetooth connectivity

      Cons

      • No recirculation kit (but recirculation kit ready)
      • No voice control
      • Direct-vent limits installation options

      The main differences between the Rinnai SE+ series and the Rheem RTGH are:

      • Hot Water Generation – the Rheem RTGH we suggest produces water at 8.4 GPM, significantly higher than the Rinnai model. 
      • Efficiency – both products provide the same amount of efficiency
      • Technology – both products come with advanced technology features, but only Rinnai offers voice control. 
      • Recirculation – The Rinnai SE+ Series comes with recirculation technology already included, while the Rheem RTGH does not, but it is recirculation pump kit ready. 

      Want to dig deeper on more options?

      See this post for reviews on the top Rheem tankless water heater units.

      The Bottom Line On the Best Condensing Tankless Water Heater

      Condensing tankless water heaters are the wave of the future. You want a condensing tankless water heater to heat the water as efficiently as possible, and you want a brand that will provide a great product and offer support when necessary. In our opinion, the Rinnai SE+ series is your best choice. 

      FAQ’s on Condensing Tankless Water Heaters:

      Is a condensing tankless water heater worth it?

      A condensing tankless water heater may not provide an immediate return on your investment. However, in time, the smaller utility bills will pay off the difference. Most people feel this makes condensing tankless water heaters worth the upfront investment. You should only make the upgrade if you plan to stay in your current home for an extended period of time. 

      What does condensing mean on a tankless water heater?

      A “condensing” tankless water heater means that the unit utilizes much of the heat generated by the unit to heat the water before sending the gases out of the home. 

      What’s the difference between condensing and non-condensing tankless water heaters?

      The main difference between condensing and non-condensing tankless water heaters is condensing units use heat from the gases to help heat the water before venting the gases. Non-condensing units vent the gas without the additional step. 

      Condensing units can use less expensive plastic PVC piping since the gas isn’t hot when vented. Non-condensing units must use a higher grade of ventilation material that can withstand the heat. Condensing tankless water heaters is more efficient than condensing units but requires additional maintenance to clean up the condensation and typically costs more upfront. 

      Are all tankless water heaters condensing?

      No. Tankless water heaters come in two options: condensing and non-condensing. Ensure you check which type of water heater it is before you make your purchase.

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      I'm passionate about all things plumbing, and love sharing tips, "how-to", and reviewing the latest products to help make your project a success!

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