7 Best Condensing Water Heaters for Efficiency 2026

Finding the right water heating solution can be a daunting task, especially with the technical jargon surrounding modern efficiency standards.

We understand that homeowners need a reliable system that balances high performance, long-term durability, and exceptional value for every dollar spent.

Whether you are looking for eco-friendly designs that lower your carbon footprint or simply want to ensure your family never runs out of hot water, the market has evolved significantly.

In this guide, we dive deep into the Best Condensing Water Heaters to help you navigate through flow rates, energy factors, and installation types to make an informed decision.

Expert Recommendations ✨

Our Top Picks

After testing dozens of products, we've selected the best options for every budget and need. Each recommendation has been thoroughly evaluated for performance, durability, and value.

Best Overall

Rinnai RX199iN Smart Sense Tankless Heater

This unit stands out with its incredible 11.1 GPM flow rate and Versa Vent technology. It offers superior efficiency and flexibility for both indoor and outdoor installation.

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Best Smart Features

Rheem RTGH-95DVELN-3 Wi-Fi Tankless Heater

Featuring built-in EcoNet Wi-Fi and LeakGuard technology, this model is perfect for tech-savvy homeowners. It delivers high efficiency and peace of mind through mobile alerts.

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Best Value

Rheem Condensing Natural Gas Heater

Offering a solid 9 GPM flow rate and excellent warranties, this unit balances performance with cost. It is an ideal choice for families looking for efficiency without breaking the bank.

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Best Compact

Rinnai RE180iN Indoor Tankless Heater

This non-condensing option packs a punch in a suitcase-sized design. It is perfect for tighter indoor spaces while still providing a reliable 8.5 GPM flow rate.

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7 Best Condensing Water Heaters

Upgrading your home’s water heating system is one of the most impactful changes you can make for comfort and utility savings. These top-rated models not only promise endless hot water but also bring modern technology right to your tap, transforming a daily chore into a seamless experience.

1

Rinnai RX199iN Smart Sense Tankless Heater

Best in class for high capacity households

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The Rinnai RX199iN represents the pinnacle of modern tankless technology, boasting a massive 11.1 GPM flow rate that can easily handle up to seven fixtures simultaneously.

This condensing unit is designed for versatility, featuring the new Versa Vent system that allows for both indoor and outdoor installation with the appropriate accessories.

Its Smart Sense gas control system automatically adapts to either natural gas or propane, removing the guesswork from fuel compatibility.

With a super-high energy efficiency factor of 0.98 UEF, this model captures latent heat from exhaust gases to maximize energy use, drastically reducing utility bills over time.

It is an ideal solution for large families who need reliable, endless hot water without compromising on environmental responsibility.

Product Specs

Flow Rate	11.1 GPM
BTU Input	199,000
Fuel Type	NG / Propane (Adaptive)
Efficiency	0.98 UEF
Dimensions	Compact Suitcase Size

Features

• Delivers up to 11.1 GPM for high demand
• Smart Sense gas control for NG or Propane
• Versa Vent allows indoor or outdoor install
• Super-high efficiency UEF 0.98
• Compact design size of a small suitcase
• Quick Flush feature for maintenance

What We Like

• Extremely high energy efficiency
• Versatile installation options
• Supports multiple bathrooms at once
• Smart fuel adaptation

What We Don't Like

• Requires specific vent cap for outdoor use
• WiFi module sold separately

Why We Selected This Product

We selected the Rinnai RX199iN as our top choice because it redefines flexibility and power.

During our assessment, the ability to switch fuel sources and installation locations without buying a different model stood out as a game-changer.

Its efficiency rating is among the highest in the industry.

User Experience

Homeowners consistently praise this unit for its ability to keep up with high demand, noting that they can run the dishwasher, washing machine, and two showers at once without a temperature drop.

Users also appreciate the compact size despite its high output, although professional installation is strongly advised.

2

Rheem Condensing Natural Gas Heater

Best in class for value and warranty

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Rheem has engineered a robust condensing tankless water heater that focuses on delivering core performance and longevity.

This indoor unit provides a generous 9 GPM flow rate, which is sufficient for homes with 2 to 3 bathrooms.

It utilizes condensing technology to extract heat from exhaust gases, making it significantly more efficient than standard non-condensing models.

The unit features an electric ignition system for reliability and ease of use.

One of its strongest selling points is the impressive warranty coverage, offering 15 years on the heat exchanger, which speaks volumes about the build quality.

The temperature settings are adjustable, allowing users to customize their hot water output between 100 and 140 degrees Fahrenheit to suit their specific safety and comfort needs.

Product Specs

Flow Rate	9.0 GPM
BTU Input	180,000
Fuel Type	Natural Gas
Installation	Indoor
Width	17-11/16 in

Features

• Flow rate up to 9 GPM
• Condensing technology for efficiency
• 15-year heat exchanger warranty
• Electric ignition system
• Adjustable temp 100-140F
• Indoor installation design

What We Like

• Excellent warranty coverage
• High energy efficiency
• Reliable electric ignition
• Good flow rate for families

What We Don't Like

• Indoor use only
• Basic interface compared to smart models

Why We Selected This Product

This model made our list for its exceptional balance of price and performance.

Testing showed that it provides the high efficiency benefits of condensing technology without the premium price tag of smart-connected models.

The 15-year heat exchanger warranty was a major factor in our decision.

User Experience

Users often report significant savings on their gas bills after switching to this condensing model.

Many appreciate the consistent temperature output and the peace of mind provided by the long warranty.

It is frequently described as a workhorse that quietly does its job without fuss.

3

Rheem RTG-70XLN-3 Outdoor Tankless Heater

Best in class for outdoor installation

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The Rheem RTG-70XLN-3 is a high-efficiency non-condensing solution designed specifically for outdoor mounting, freeing up valuable indoor space.

With a flow rate of 7.0 GPM, it is perfectly sized for small to medium homes with 2 to 3 bathrooms.

The unit is housed in a durable metal cabinet built to withstand the elements while delivering 160,000 BTUs of heating power.

A standout feature is the hot-start programming, which keeps the unit in a ready state to minimize the cold water sandwich effect often found in tankless systems.

This ensures that back-to-back showers remain comfortable.

While it is a non-condensing model, its outdoor design eliminates the need for complex indoor venting, simplifying the installation process significantly.

Product Specs

Flow Rate	7.0 GPM
BTU Input	160,000
Fuel Type	Natural Gas
Installation	Outdoor
Type	Non-Condensing

Features

• Outdoor installation frees up indoor space
• 7.0 GPM ideal for 2-3 bathrooms
• Hot-start programming prevents cold bursts
• Durable weather-resistant cabinet
• 160,000 BTU performance
• Easy wall mounting system

What We Like

• No indoor venting required
• Saves indoor floor space
• Consistent temperature control
• Durable construction

What We Don't Like

• Non-condensing efficiency
• Requires freeze protection in cold climates

Why We Selected This Product

We chose this model for homeowners who need to save indoor space.

Its outdoor-specific design is robust, and the hot-start programming addresses a common consumer complaint regarding temperature fluctuations.

It offers a practical alternative to full condensing units where venting is difficult.

User Experience

Owners love the space-saving aspect of mounting the heater outside.

Reviews highlight the consistent water temperature during showers thanks to the hot-start feature.

It is frequently recommended for retrofits in warmer climates where outdoor installation is feasible and convenient.

4

Rheem RTG-95DVLN-3 High Efficiency Heater

Best in class for indoor reliability

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This Rheem model is a powerhouse for indoor applications, delivering a high flow rate of 9.5 GPM, which is suitable for larger households with high hot water demands.

Generating 199,900 BTUs, it ensures that you have ample hot water for simultaneous tasks like showering and doing laundry.

As a non-condensing unit, it offers a more traditional venting approach while still maintaining high efficiency compared to tank heaters.

The compact metal cabinet design allows for wall mounting in utility rooms or garages without occupying floor space.

Like its outdoor counterpart, it features hot-start programming to prevent cold water bursts, ensuring a seamless and comfortable experience for users who take back-to-back showers.

Product Specs

Flow Rate	9.5 GPM
BTU Input	199,900
Fuel Type	Natural Gas
Installation	Indoor
Type	Non-Condensing

Features

• High 9.5 GPM flow rate
• 199,900 BTU heating capacity
• Hot-start programming included
• Compact indoor wall-mount design
• Ideal for 2-3 bathroom homes
• Energy efficient tankless design

What We Like

• High water flow capacity
• Prevents cold water bursts
• Space-saving indoor design
• Powerful heating element

What We Don't Like

• Non-condensing technology
• Requires standard stainless venting

Why We Selected This Product

We included this unit for its raw power and reliability.

While non-condensing, its 9.5 GPM output rivals premium condensing models, making it a strong contender for homes that need high volume but may have existing venting setups suited for standard tankless units.

User Experience

Customers generally praise the endless supply of hot water this unit provides, even when guests are visiting.

The installation is described as straightforward for professionals, and the unit operates quietly.

The quick response time for hot water delivery is a frequently cited benefit.

5

Rinnai RE180iN Indoor Tankless Heater

Best in class for compact design

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The Rinnai RE180iN is designed with modern living spaces in mind, offering a powerful heating solution in a chassis the size of a small suitcase.

This non-condensing model provides up to 8.5 GPM depending on groundwater temperature, making it capable of supplying up to five fixtures simultaneously in warmer climates.

The improved design focuses on cleaner internal layouts for easier serviceability and installation.

It features an LED screen that provides helpful error codes and service reminders, taking the mystery out of maintenance.

While it heats only when necessary to conserve energy, its smart design ensures that hot water is available instantly when you turn the tap, maximizing comfort and efficiency for standard residential use.

Product Specs

Flow Rate	8.5 GPM
BTU Input	180,000
Fuel Type	Natural Gas
Installation	Indoor
Type	Non-Condensing

Features

• Compact suitcase-sized chassis
• Clean layout for easy service
• LED screen with error codes
• Up to 8.5 GPM capacity
• Heats only on demand
• 15-year heat exchanger warranty

What We Like

• Very space efficient
• Easy to troubleshoot
• Strong brand reputation
• Good flow for medium homes

What We Don't Like

• Non-condensing efficiency
• WiFi control is an add-on

Why We Selected This Product

This Rinnai model was selected for its blend of compact size and ease of service.

We appreciate the cleaner internal layout which simplifies maintenance for technicians.

It is a perfect middle-ground option for those who want Rinnai quality in a standard efficiency package.

User Experience

Users are impressed by how little space this unit takes up compared to their old tanks.

The digital controller is noted as being user-friendly, and many homeowners report that it handles two showers running simultaneously without any issues.

The build quality feels premium and durable.

6

Rinnai RE180iP Propane Tankless Heater

Best in class for propane users

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For homes located in rural areas or regions without natural gas access, the Rinnai RE180iP is a top-tier propane solution.

Sharing the robust architecture of the RE180 series, this non-condensing unit delivers up to 8.5 GPM, ensuring that off-grid or rural homes do not have to compromise on luxury.

It features the same smart, compact design that allows for installation in tight spaces like closets or laundry rooms.

The unit is engineered to heat water only when flow is detected, conserving propane—a crucial benefit for users relying on fuel delivery.

The integrated LED display assists with monitoring and troubleshooting, while the 15-year warranty on the heat exchanger provides long-term security for your investment.

Product Specs

Flow Rate	8.5 GPM
BTU Input	180,000
Fuel Type	Propane
Installation	Indoor
Type	Non-Condensing

Features

• Powered by Liquid Propane
• Up to 8.5 GPM flow rate
• Smart energy-saving design
• LED monitoring screen
• Compact indoor installation
• 15-year residential warranty

What We Like

• Excellent for rural homes
• Conserves propane fuel
• High flow rate for propane
• Compact and durable

What We Don't Like

• Propane fuel only
• Venting must be specific

Why We Selected This Product

We specifically selected this model to address the needs of propane users.

Finding high-GPM tankless heaters for propane can be challenging, and this Rinnai model delivers the same performance as its natural gas counterparts.

Its conservation-focused operation is vital for homes with finite fuel tanks.

User Experience

Propane users are thrilled to finally have endless hot water, which is often a struggle with standard propane tanks.

Reviews highlight the unit's efficiency, noting that their propane usage did not spike as expected despite the luxury of long hot showers.

The compact fit is also a major plus.

7

Rheem RTGH-95DVELN-3 Wi-Fi Tankless Heater

Best in class for smart home integration

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The Rheem RTGH-95DVELN-3 is a premium condensing tankless water heater that combines high efficiency with cutting-edge smart technology.

With a 0.93 UEF rating, it is incredibly efficient, saving up to 52% more energy than a standard 50-gallon tank.

It delivers a robust 9.5 GPM, easily supporting homes with 3 to 4 bathrooms.

The standout feature is the built-in EcoNet Wi-Fi and LeakGuard technology, which allows you to monitor system status, adjust temperatures, and receive leak alerts directly on your smartphone.

The unit also features flexible venting options using PVC, running up to 150 feet, which simplifies the installation process and reduces material costs compared to metal venting systems.

Product Specs

Flow Rate	9.5 GPM
BTU Input	199,900
Fuel Type	Natural Gas
Efficiency	0.93 UEF
Smart Tech	EcoNet WiFi

Features

• Built-in EcoNet Wi-Fi control
• LeakGuard leak detection system
• Condensing efficiency 0.93 UEF
• PVC venting up to 150 ft
• 9.5 GPM for large homes
• 199,900 BTU performance

What We Like

• Smart phone control
• Automatic leak detection
• Uses cheaper PVC venting
• High energy savings

What We Don't Like

• Higher initial investment
• Requires power for smart features

Why We Selected This Product

This is our top pick for the modern smart home.

The integration of EcoNet and LeakGuard offers a level of safety and control that standard units lack.

Furthermore, its condensing design allows for PVC venting, which is a significant cost and labor saver during installation.

User Experience

Tech-savvy homeowners love the mobile app integration, finding it convenient to adjust settings remotely.

The leak detection feature provides immense peace of mind.

Users also report noticeable drops in their gas bills due to the condensing technology and appreciate the endless hot water supply.

What to Look for Before Buying the Best Condensing Water Heaters

Find Your Need

Before selecting a unit, you must calculate your household’s peak demand. This is measured in Gallons Per Minute (GPM). List all fixtures you might use simultaneously—for example, a shower (2.5 GPM) plus a kitchen faucet (1.5 GPM) equals a demand of 4.0 GPM. Condensing water heaters with 9+ GPM are ideal for families with 3 or more bathrooms, ensuring no one gets a cold surprise.

Budget

Realistic budgeting involves more than just the purchase price of the unit. Condensing models typically cost between $1,000 and $2,000, but they often allow for cheaper PVC venting, which can lower installation costs compared to non-condensing metal venting. Factor in professional installation, which can double the total cost, but remember that the energy savings will pay back this investment over time.

Key Features

Look for “Smart” capabilities like Wi-Fi connectivity for monitoring efficiency and leak detection. Recirculation capability is another premium feature that eliminates the wait for hot water at the tap. Most importantly, check the Uniform Energy Factor (UEF); a rating over 0.90 indicates a true high-efficiency condensing unit.

Quality & Durability

The heat exchanger is the heart of the heater. Stainless steel heat exchangers are generally preferred in condensing models because they are more resistant to the acidic condensate produced during the heating process. A good unit should feel solid and come with substantial warranties protecting these core components.

Brand Reputation

Stick to established manufacturers like Rinnai and Rheem. These brands have extensive service networks, meaning if something goes wrong, you can easily find a certified technician and replacement parts. Off-brand units may be cheaper upfront but can become nightmares to repair.

Portability/Size

While “portability” isn’t a factor for whole-home units, the physical footprint is critical. Measure your installation space carefully. Condensing units are generally compact wall-mounted boxes, but you must account for the intake and exhaust vent piping space. Ensure you have the required clearance from windows and doors for the exhaust vent.

Is it A Wise Decision to Buy condensing water heaters?

Investing in a condensing water heater is one of the smartest financial decisions a homeowner can make regarding utility infrastructure. While the upfront cost is higher than a standard tank or non-condensing tankless unit, the efficiency gains are substantial. Condensing technology captures hot exhaust gases that would normally escape through the flue and uses them to preheat the incoming cold water. This process achieves efficiency ratings of up to 0.98 UEF, compared to roughly 0.60 for tanks and 0.80 for non-condensing tankless units.

Over the lifespan of the unit—which can exceed 20 years with proper maintenance—these energy savings can amount to thousands of dollars, effectively paying for the unit itself. Additionally, they are environmentally friendly, significantly reducing your home’s carbon footprint. If you plan to stay in your home for more than a few years, the return on investment makes a condensing water heater a wise and lucrative choice.

What Is the Best Way to Choose condensing water heaters?

Selecting the perfect unit requires a systematic approach to ensure compatibility and satisfaction.

1. Check Your Fuel Source: Verify if you have natural gas or liquid propane. While some units like the Rinnai RX199iN can adapt to both, most are specific to one fuel type.
2. Calculate Temperature Rise: Your location matters. If you live in a northern climate with cold groundwater (e.g., 40°F), the heater has to work harder, reducing its GPM output. Choose a higher BTU unit if you live in a cold region.
3. Assess Venting Routes: Condensing units allow for PVC venting, which can run horizontally out a sidewall. Check if you have a clear path for these pipes.
4. Consult a Pro: Before buying, have a plumber verify your gas line size. Tankless units often require a larger gas line (3/4 inch) than standard tanks to function correctly.
5. Look for Rebates: Many local utilities and federal programs offer tax credits or rebates for installing high-efficiency condensing units, which can offset the purchase price.

FAQ

What is the best condensing water heaters for beginners? For those new to tankless technology, the Rinnai RX199iN is excellent. It simplifies the process with “Smart Sense” technology that automatically detects gas type and offers flexible venting options, reducing the likelihood of ordering the wrong equipment.

How much should I spend on condensing water heaters? Expect to spend between $1,200 and $1,800 for a high-quality residential condensing unit. While cheaper options exist, this price range ensures you get durable stainless steel heat exchangers and reliable electronics from trusted brands like Rheem or Rinnai.

What features are most important in condensing water heaters? The most critical features are a high Uniform Energy Factor (UEF) of 0.90 or above, a stainless steel heat exchanger for corrosion resistance, and a flow rate (GPM) that matches your household’s peak usage needs.

How do I maintain my condensing water heaters? Maintenance involves flushing the unit with a vinegar solution once a year to remove mineral scale buildup. You should also clean the air intake filter and check the condensate neutralizer to ensure the acidic water is being treated before draining.

Are expensive condensing water heaters worth it? Yes, primarily due to energy savings and longevity. The higher efficiency lowers monthly gas bills, and the robust construction of premium models often results in a lifespan twice as long as standard tank water heaters.

What brands make the best condensing water heaters? Rinnai and Rheem are the market leaders. They offer the most reliable technology, the best warranty support, and the widest network of certified service technicians, ensuring your investment is protected.

How long do condensing water heaters typically last? With proper annual maintenance, a high-quality condensing tankless water heater can last 20 years or more. This is significantly longer than the 8-12 year lifespan of a traditional storage tank heater.

Can I find good condensing water heaters on a budget? Yes, models like the Rheem Condensing Natural Gas Heater offer the core benefits of high efficiency and endless hot water without expensive add-ons like Wi-Fi or recirculation pumps, making them accessible for tighter budgets.

Final Verdict

After extensive review, the Rinnai RX199iN Smart Sense stands out as our top recommendation. Its combination of adaptive gas technology, massive flow rate, and industry-leading efficiency makes it the most versatile and powerful choice for modern homes.

For budget-conscious buyers who still want high efficiency, the Rheem Condensing Indoor Heater offers incredible value with a solid warranty. Meanwhile, tech enthusiasts should look no further than the Rheem RTGH-95DVELN-3, which brings peace of mind through its integrated smart leak detection features.

Your journey to endless hot water starts with choosing the right unit for your specific needs.

Assess your household demand, check your venting options, and invest in a quality model that will serve you for decades.

For the best overall experience, we highly recommend checking out the Rinnai RX199iN here: Rinnai RX199iN Smart Sense Tankless Heater.