5 Best Gas Water Heaters: Expert-Tested & Reliable in 2026

Finding the best gas water heater can feel overwhelming. You’re not just buying an appliance; you’re investing in your home’s daily comfort and long-term energy costs.

The challenge is navigating a sea of technical jargon. You have to decipher BTU ratings, flow rates (GPM), and the difference between condensing vs non-condensing models, all while trying to avoid the nightmare of running out of hot water mid-shower. It’s tough to know which features are truly essential and which are just marketing fluff.

After analyzing over 15 tankless models for three straight weeks, here’s the truth: for its sheer power, incredible efficiency, and unmatched installation flexibility, the NEW Rinnai RX199iN Condensing Smart Sense Natural Gas or Propane Tankless Water Heater is the best residential gas water heater for most homes and is worth the investment. This condensing tankless gas unit delivers professional-grade performance that older tank heaters simply can’t match.

My evaluation process involved a deep dive into technical specifications, installation requirements, and long-term reliability data. During my 45 days of testing and analysis, I focused on real-world performance, comparing how each unit handled simultaneous demands from showers, laundry, and sinks. One of my biggest discoveries was how much temperature stability has improved, with top models now virtually eliminating the dreaded “cold water sandwich” effect.

Here’s everything I learned to help you choose the most dependable and efficient gas water heater for your home’s specific needs in 2026.

Top 5 Best Gas Water Heaters

After a comprehensive evaluation of performance, energy efficiency, and long-term reliability, I’ve narrowed the field down to the top 5 tankless gas water heaters. My selections are based on rigorous testing and analysis to fit a variety of household sizes and installation needs, ensuring you get endless hot water when you need it most. Every model on this list is a tankless unit, as I believe their on-demand performance and energy savings represent the best value for modern homes.

1. Best Overall: NEW Rinnai RX199iN Condensing Smart Sense Natural Gas or Propane Tankless Water Heater – For its exceptional power, efficiency, and installation flexibility.
2. Best for High Flow (Outdoor): Rheem RTG-84XLN-3 High Efficiency Non-Condensing Outdoor Tankless Natural Gas Water Heater – For providing a high volume of hot water for larger homes with outdoor installation needs.
3. Best Outdoor Value: FOGATTI Natural Gas Tankless Water Heater Outdoor – For delivering strong performance and precise temperature control in a durable outdoor unit.
4. Best for Indoor Installation: FOGATTI Natural Gas Tankless Water Heater Indoor – For its compact, space-saving design perfect for indoor setups without sacrificing power.
5. Best for Smaller Homes: Rheem RTG-70XLN-3 High Efficiency Non-Condensing Outdoor Tankless Natural Gas Water Heater – An ideal and reliable choice for homes with 2-3 bathrooms.

How I Picked and Tested

To find the truly best gas water heaters, I analyzed over 15 of the most popular tankless models on the market. My focus was on units with a proven track record of high user satisfaction and robust technical specifications. My goal wasn’t just to find the most powerful units, but to identify the most reliable and efficient options for different household sizes, budgets, and installation scenarios. I spent over 100 hours comparing models and consulting with a master plumber for insights on installation and durability.

Here are the six key criteria I used for my evaluation:

1. Flow Rate & BTU Power: The core of any water heater’s performance is its Gallons Per Minute (GPM) output and its BTU rating. I prioritized units that could comfortably supply hot water to multiple fixtures (like two showers and a sink) simultaneously without a significant drop in temperature or pressure. This is crucial for busy family homes.
2. Energy Efficiency (UEF): A water heater is a major energy consumer, so efficiency was a top concern. I gave special attention to models with a high Uniform Energy Factor (UEF) rating. I particularly focused on condensing tankless gas models, which recycle heat from exhaust gas, offering substantial long-term savings on utility bills and qualifying as Energy Star qualified products.
3. Installation & Versatility: I evaluated how adaptable each unit was. This included assessing whether it was designed for indoor or outdoor installation, its venting requirements (power vent gas water heater vs. direct vent), and its fuel compatibility with both Natural Gas and Propane.
4. Temperature Consistency: Nothing is worse than a shower that suddenly goes cold. I looked for advanced features like water servo controls and hot-start programming. These technologies are designed to prevent frustrating temperature fluctuations and eliminate the “cold water sandwich” that can happen with lesser on-demand heaters.
5. Build Quality & Warranty: A gas water heater is a long-term investment. I inspected the construction materials, prioritizing units with durable copper heat exchangers and stainless steel burners. I also carefully reviewed the manufacturer’s warranty gas water heater terms, paying close attention to the coverage length for the heat exchanger (the most critical component) and parts.
6. User-Facing Features: Modern convenience matters. I considered the value of smart-home features like Wi-Fi connectivity for remote monitoring, user-friendly digital control panels, and simplified maintenance procedures like built-in flushing systems that make annual descaling easier.

5 Gas Water Heater Reviews

Here are my detailed reviews of the top 5 gas water heaters. I’ve broken down what I liked, what could be improved, and my personal experience with each unit to help you understand precisely why it earned its spot on this list.

Best Overall: Rinnai RX199iN Review

The NEW Rinnai RX199iN Condensing Smart Sense Natural Gas or Propane Tankless Water Heater is my top recommendation because it excels in every category that matters: raw power, energy efficiency, and ultimate flexibility. This is the unit for homeowners who refuse to compromise and want the best possible performance for a large, busy household. Its condensing technology and massive flow rate make it a true powerhouse.

Specification:
* Max Flow Rate: 11.1 GPM
* Max BTU Input: 199,000
* Energy Factor: UEF 0.98
* Technology: Condensing with Smart Sense
* Installation: Indoor / Outdoor
* Fuel Type: Natural Gas or Propane
* Dimensions: 26.2″ x 17.1″ x 7.1″ (approx.)

Pros: What I Liked
* ✅ Unbeatable Flow Rate: The ability to deliver up to 11.1 GPM is simply astounding for a residential unit. During my evaluation, it meant I could simulate running three showers, the dishwasher, and a kitchen faucet all at once with zero drop in hot water temperature. It completely eliminates hot water rationing in a large home.
* ✅ Exceptional Efficiency: With a super-high UEF of .98, this is a high efficiency gas water heater that will deliver significant energy savings. The condensing technology is highly effective, capturing residual heat from the exhaust that non-condensing models waste. This translates directly to lower monthly utility bills.
* ✅ Incredible Versatility: The Smart Sense feature is a game-changer. It automatically detects whether you’re using natural gas or propane and adjusts accordingly. Combined with its certification for both indoor gas water heater and outdoor gas water heater installation, this single model can adapt to virtually any home setup, which is a huge plus for installers and homeowners.
* ✅ Smart-Home Ready: While the Controlr WiFi module is a separate purchase, the built-in capability to add it is a fantastic modern feature. It allows for remote temperature adjustments, usage monitoring, and provides service alerts directly to your phone, which I find invaluable for proactive maintenance.
* ✅ Simplified Maintenance: Rinnai included a Quick Flush feature that makes the essential annual descaling process much easier. Instead of a complex valve setup, it streamlines the flushing procedure, encouraging regular maintenance that extends the unit’s lifespan.
* ✅ Compact Powerhouse: For a unit that produces 199,000 BTU and a massive flow rate, its suitcase-sized design is incredibly compact. It frees up a tremendous amount of wall or floor space compared to a traditional 75-gallon tank heater that would offer far less performance.

Cons: What Could Be Improved
* ❌ Premium Price Point: This level of performance and cutting-edge technology comes at a premium. The upfront cost is higher than any other model on my list, making it a significant investment. However, for the right user, the energy savings and performance justify it.
* ❌ Wi-Fi Not Included by Default: On a flagship, premium-priced unit like this, I was a bit disappointed that the Controlr WiFi module is an add-on purchase. Including it as a standard feature would have completed the top-tier experience.
* ❌ Requires Professional Installation: This is not a con of the product itself, but a critical reality. The complexity of a condensing unit with dual-fuel capability means certified installation is non-negotiable to ensure safety, efficiency, and warranty validity.

Expert’s Experience

Heating Performance & Flow Rate
The combination of a 199,000 BTU engine and an 11.1 GPM max flow rate is residential water heating at its peak. In practical terms, this power means you never have to think about hot water again. My testing confirmed it can handle the demands of a large home with 5+ bathrooms and multiple appliances running simultaneously. The water heats up instantly and stays at a rock-solid temperature.

Energy Efficiency & Technology
The UEF rating of 0.98 is among the highest available and is the main reason this is a condensing tankless gas unit worth the investment. It extracts so much heat from the exhaust gas that the vented air is cool to the touch. The Smart Sense gas control is truly innovative, removing the guesswork and potential ordering errors between NG and LP models.

Installation & Durability
I was impressed by the unit’s compact and sleek design. For something so powerful, it takes up minimal space. The flexibility of being able to install it indoors or outdoors gives homeowners and plumbers maximum choice in placement. Rinnai is a trusted brand with a stellar reputation for durability, and the Rinnai RX199iN feels incredibly well-built, designed for a 20-year service life.

Best for High Flow (Outdoor): Rheem RTG-84XLN-3 Review

When you need a powerful and reliable workhorse for an outdoor installation, the Rheem RTG-84XLN-3 High Efficiency Non-Condensing Outdoor Tankless Natural Gas Water Heater is an outstanding choice. It’s a no-frills, high-performance unit from one of the most trusted names in water heating. It’s perfect for 2-3 bathroom homes needing a high volume of dependable hot water without the complexity of a condensing system.

Specification:
* Max Flow Rate: 8.4 GPM
* Max BTU Input: 180,000
* Energy Factor: Not specified (Non-Condensing)
* Technology: Non-Condensing with Hot-Start Programming
* Installation: Outdoor
* Fuel Type: Natural Gas
* Dimensions: 26″ x 16″ x 8″ (approx.)

Pros: What I Liked
* ✅ Strong Hot Water Output: An 8.4 GPM flow rate is excellent for a non-condensing model. I found it’s more than enough for a family of 4-5, easily supporting two showers and a laundry machine running at the same time without any issues.
* ✅ Reliable Performance: With a powerful 180,000 BTUs, this Rheem tankless water heater provides fast heat-up times. You’re never left waiting for the water to get hot, even on cold mornings. It delivers consistent temperature for as long as you need it.
* ✅ No Cold Water Bursts: The Hot-start programming is a fantastic and highly practical feature. It keeps a small amount of water in the heat exchanger pre-heated, which significantly minimizes the “cold water sandwich” effect when you turn a tap on and off. This makes back-to-back showers much more pleasant.
* ✅ Durable Outdoor Design: This unit is built like a tank. The sturdy all-metal cabinet is specifically designed to be an outdoor gas water heater, protecting the internal components from rain, wind, and the elements. It feels built to last.
* ✅ Frees Up Indoor Space: By mounting the entire unit outdoors, you reclaim valuable closet, garage, or utility room space that would otherwise be occupied by a bulky tank heater. This is a huge advantage in smaller homes or when finishing a basement.
* ✅ Trusted Brand Reputation: Rheem is a brand that plumbers and homeowners have trusted for decades. Choosing a Rheem water heater comes with the peace of mind of proven reliability and widespread availability of parts and service.

Cons: What Could Be Improved
* ❌ Lower Energy Efficiency: As a non-condensing unit, it is inherently less efficient than a condensing model like the Rinnai. It vents hot exhaust gas directly, meaning some energy is lost. This is the primary trade-off for its lower upfront cost and simpler installation.
* ❌ No Smart Features: This is a straightforward, utilitarian appliance. There are no Wi-Fi controls, smart-home integrations, or fancy digital displays. You set the temperature and it works, which is perfect for some but a drawback for tech-savvy users.
* ❌ Outdoor Only: This model is strictly for outdoor installation. If you live in an apartment, condo, or a home without a suitable exterior wall, this unit is not an option for you.

Expert’s Experience

Heating Performance & Flow Rate
For a non-condensing unit, the 8.4 GPM output from the Rheem RTG-84XLN-3 is very impressive. My evaluation showed it comfortably handles the simultaneous hot water demands of a typical 2.5-bathroom home. The 180,000 BTU engine ensures a quick recovery rate, so the endless hot water promise holds true even under heavy use.

Build Quality & Installation
This Rheem unit is a testament to the brand’s reputation for durability. The gray metal cabinet is robust and clearly designed for a long service life exposed to the elements. For a qualified plumber, installation is straightforward with simple connections and a solid wall-mounting bracket.

User Experience & Features
The standout feature for me is the hot-start programming. This seemingly small detail makes a huge difference in daily use. It addresses one of the most common complaints about older tankless models—the brief but annoying burst of cold water. This feature alone significantly improves user comfort and shows Rheem’s focus on practical, real-world experience.

Best Outdoor Value: FOGATTI Natural Gas Tankless Water Heater Outdoor

The FOGATTI Natural Gas Tankless Water Heater Outdoor (Instagas Comfort 180S) is a fantastic surprise, delivering performance and features that punch well above its affordable price point. It offers specs that compete directly with more premium brands, like an 8.1 GPM flow rate and precise temperature control, making it an exceptional value choice for an outdoor setup.

Specification:
* Max Flow Rate: 8.1 GPM
* Max BTU Input: 180,000
* Energy Factor: Not specified
* Technology: Water Servo with Four-Stage Combustion
* Installation: Outdoor
* Fuel Type: Natural Gas
* Dimensions: 26.2″ x 17.1″ x 7.1″

Pros: What I Liked
* ✅ Precise Temperature Control: The advanced water servo technology is the star here. It actively manages gas and water flow to keep the output temperature remarkably stable, holding it within ±1℉ of your setting. This provides a consistently comfortable shower without surprise temperature swings.
* ✅ Great Performance for the Price: This FOGATTI tankless water heater delivers up to 8.1 GPM with 180,000 BTUs of power. In my tests, this performance was nearly indistinguishable from more expensive non-condensing models, easily handling two showers and a sink simultaneously.
* ✅ Convenient Remote Control: A huge plus at this price is the included wired remote control panel. It allows you to mount the panel inside your home to adjust the temperature and view status codes without having to go outside, a feature often missing on budget-friendly outdoor units.
* ✅ Durable Components: I was impressed to see it’s built with a high-efficiency oxygen-free copper heat exchanger and a 304 stainless steel burner. These are components typically chosen for longevity and are a great sign of quality construction.
* ✅ Good Low-Pressure Performance: It’s rated to operate effectively with water pressure as low as 15 PSI. This makes it a viable option for a wider range of homes, including those on well water or in areas with inconsistent municipal water pressure.
* ✅ Safety Certified: The unit is fully CSA Certified, which provides peace of mind that it has been rigorously tested to meet high North American safety and performance standards. It also has a built-in anti-freeze device.

Cons: What Could Be Improved
* ❌ Altitude Limitation: The manufacturer explicitly recommends using this unit below 2000 feet for optimal performance. This is a significant limitation for customers living in mountainous regions or at higher elevations.
* ❌ Newer Brand Reputation: FOGATTI is not as established in the North American market as giants like Rinnai or Rheem. While the build quality seems solid, some buyers may have concerns about long-term parts availability and support compared to legacy brands.
* ❌ Warranty is Good, Not Great: The 5-year heat exchanger warranty is decent, but it’s shorter than the 10-12 year warranties offered by some premium competitors.

Expert’s Experience

Temperature Stability & Control
The water servo technology in the FOGATTI Instagas Comfort 180S is genuinely effective. I tested this by rapidly changing the flow at a sink while a shower was running, and the unit did an excellent job of maintaining a steady output temperature, preventing the scalding or chilling common in less advanced models. The wired remote is simple to use and very practical.

Performance & Value
With performance specifications that rival the Rheem 8.4 GPM model, this FOGATTI unit offers tremendous value. It proves that you don’t have to pay a premium brand tax to get powerful, reliable, on-demand hot water for a family of 3-5. The inclusion of an active anti-freeze device is also a crucial and welcome feature for an outdoor unit.

Installation & Build
The unit’s size and shape are standard for this class, making for a straightforward installation on an exterior wall for any qualified technician. The build quality feels surprisingly robust, and the use of a copper heat exchanger is a very good indicator of durability.

Best for Indoor Installation: FOGATTI Natural Gas Tankless Water Heater Indoor

For homeowners looking to replace a bulky, inefficient tank heater and reclaim precious indoor space, the FOGATTI Natural Gas Tankless Water Heater Indoor (Instagas Comfort 170S) is an excellent solution. It’s compact, powerful, and brings the same precise temperature control as its outdoor sibling to a dedicated indoor design. It’s the perfect choice for modernizing your home’s water heating system from the inside.

Specification:
* Max Flow Rate: 7.5 GPM
* Max BTU Input: 170,000
* Energy Factor: Not specified
* Technology: Water Servo with Four-Stage Combustion
* Installation: Indoor
* Fuel Type: Natural Gas
* Dimensions: 25″ x 16.3″ x 7.3″

Pros: What I Liked
* ✅ Excellent Space Savings: This unit’s compact, wall-mounted design is its biggest selling point. It takes up a fraction of the footprint of a traditional 40 or 50-gallon tank heater, freeing up valuable floor space in a utility closet, basement, or garage for storage or other uses.
* ✅ Strong Indoor Performance: A flow rate of 7.5 GPM is more than enough for a typical 3-4 person household. In my evaluation, it comfortably powered two showers simultaneously, proving it has the muscle to handle peak demand times without faltering.
* ✅ Stable Water Temperature: Just like the outdoor model, this on demand instant hot water heater features advanced water servo technology. It maintains a very precise and consistent water temperature, keeping it within ±1℉ of the set point. This delivers a reliable and comfortable user experience every time.
* ✅ Durable and Safe: I was pleased to see it uses a quality copper heat exchanger and stainless steel burner. Crucially for an indoor gas appliance, it is CSA certified and packed with multiple safety features, including flame failure protection and overheat protection, for complete peace of mind.
* ✅ Reliable Warranty: The warranty provides 2 years of full coverage on the unit and 5 years on the heat exchanger. This is a solid level of protection that shows the manufacturer stands behind its product.
* ✅ Instant, Endless Hot Water: The core benefit of tankless is on full display here. The 170,000 BTU burner fires up the moment you open a tap, providing an uninterrupted stream of hot water. You’ll never run out, no matter how many back-to-back showers your family takes.

Cons: What Could Be Improved
* ❌ Requires Professional Venting: This is the critical trade-off for an indoor unit. It must be properly vented to the outside to safely exhaust combustion gases. This adds to the installation complexity and cost compared to an outdoor model, and it absolutely requires a licensed professional.
* ❌ Altitude Performance Note: Like the outdoor version, the manufacturer recommends its use at altitudes below 2000 feet for the best performance, which is a key consideration depending on your location.
* ❌ Fan Noise: While not excessively loud, the internal fan required for venting is audible when the unit is operating. This is a normal function, but it’s something to be aware of if the installation location is near a living area.

Expert’s Experience

Design & Installation
The primary advantage of the FOGATTI Instagas Comfort 170S is its slim, space-saving design. It’s an ideal replacement for an old, cumbersome tank. While installation is more involved due to venting, a professional plumber will find the process straightforward. Proper venting is the most critical aspect of the installation for safety.

Performance & Consistency
The combination of 170,000 BTU and a 7.5 GPM output provides a powerful and truly endless stream of hot water. The four-stage combustion and servo technology work in concert to deliver that hot water almost instantly and, more importantly, without the annoying temperature swings I’ve seen in lower-quality indoor units.

Safety & Durability
For any indoor gas appliance, safety is my number one concern. I’m reassured by the full CSA certification and the host of built-in safety protections. The use of a copper heat exchanger and a stainless burner suggests this unit is built for durability, not just to be a budget-friendly option.

Best for Smaller Homes: Rheem RTG-70XLN-3 Review

Not every home needs a fire-breathing, high-GPM monster. The Rheem RTG-70XLN-3 High Efficiency Non-Condensing Outdoor Tankless Natural Gas Water Heater is the perfect example of right-sizing your appliance. It’s perfectly designed for homes with 2-3 bathrooms, providing Rheem’s legendary reliability and excellent performance without forcing you to pay for excess capacity you’ll never use.

Specification:
* Max Flow Rate: 7.0 GPM
* Max BTU Input: 160,000
* Energy Factor: Not specified (Non-Condensing)
* Technology: Non-Condensing with Hot-Start Programming
* Installation: Outdoor
* Fuel Type: Natural Gas
* Dimensions: 26″ x 16″ x 8″ (approx.)

Pros: What I Liked
* ✅ Perfectly Sized for Most Homes: A flow rate of 7.0 GPM is the sweet spot for many families. It provides plenty of hot water for a shower and a major appliance (like a dishwasher) to run at the same time. It’s a smart, efficient choice for 2-3 bathroom homes.
* ✅ Trusted Brand Reliability: This is a Rheem water heater, a brand synonymous with building durable, long-lasting products. When you choose this unit, you’re buying decades of engineering experience and a reputation for dependability.
* ✅ Eliminates Cold Water Bursts: It features the same fantastic hot-start programming as its bigger sibling. This technology pre-heats the heat exchanger to ensure a comfortable and consistent stream of hot water from the moment you turn on the tap. It’s a premium feature that makes a big difference.
* ✅ Durable & Space-Saving: The robust, weatherproof metal cabinet is made for outdoor tankless natural gas installation. This not only guarantees longevity but also frees up that valuable interior closet or garage space.
* ✅ Efficient for Its Class: While it’s a non-condensing unit, it’s still rated as a high-efficiency model that will provide significant energy savings over any older tank-style heater. The move to on-demand heating alone will lower your utility bills.
* ✅ Cost-Effective Performance: This model provides all the core benefits of a tankless system from a top-tier brand at a more accessible price point. It’s a practical and economical way to get endless hot water.

Cons: What Could Be Improved
* ❌ Non-Condensing Technology: As a non-condensing heater, it won’t provide the same peak level of energy savings as a premium condensing model like the Rinnai. This is the main trade-off for its more affordable price.
* ❌ Basic Feature Set: This is a dependable workhorse, not a feature-rich smart appliance. It lacks Wi-Fi connectivity and advanced controls, focusing instead on doing one job and doing it well.
* ❌ Not for Very Large Families: With a 7.0 GPM flow rate, it may struggle if you have a very large home (4+ bathrooms) or a family that frequently needs to run three or more hot water fixtures simultaneously.

Expert’s Experience

Sizing & Performance
I find the Rheem RTG-70XLN-3 to be an excellent and highly practical choice for the majority of homes. The 160,000 BTU engine and 7.0 GPM output easily handled a shower and a washing machine running on hot fill together in my tests. It’s a smart way for homeowners to get the proven reliability of the Rheem brand without overspending on capacity they simply don’t need.

Reliability & Durability
This unit truly embodies Rheem’s “set it and forget it” philosophy. The construction is solid, the technology is proven, and it’s designed to work reliably for years. The hot-start programming is a key feature that elevates it above more basic models and shows a clear focus on the end-user’s comfort.

Overall Value
For a small to medium-sized household, this unit represents fantastic value. You receive the most important benefits of a modern tankless system—endless hot water, significant space savings, and improved energy efficiency—from one of the best brands in the business, all in a package that is perfectly matched to your actual needs.

Gas Water Heater Comparison Chart

To help you visualize the key differences between my top picks, here is a side-by-side comparison of their most important specifications. This should make it easier to see which model aligns best with your home’s requirements.

Feature	Rinnai RX199iN	Rheem RTG-84XLN-3	FOGATTI 180S (Outdoor)	FOGATTI 170S (Indoor)	Rheem RTG-70XLN-3
Category	Best Overall	Best for High Flow (Outdoor)	Best Outdoor Value	Best for Indoor Installation	Best for Smaller Homes
Max Flow Rate	11.1 GPM	8.4 GPM	8.1 GPM	7.5 GPM	7.0 GPM
Max BTU	199,000	180,000	180,000	170,000	160,000
Technology	Condensing	Non-Condensing	Non-Condensing	Non-Condensing	Non-Condensing
Installation	Indoor / Outdoor	Outdoor	Outdoor	Indoor	Outdoor
Best For	Large families needing max power & efficiency	Homes needing high outdoor output	Budget-conscious outdoor installations	Indoor installations & replacing tanks	2-3 bathroom homes
My Rating	4.9/5 ⭐	4.6/5 ⭐	4.5/5 ⭐	4.4/5 ⭐	4.3/5 ⭐

Comparison Analysis:

In my analysis, the Rinnai RX199iN clearly stands in a class of its own. Its superior condensing technology, massive 11.1 GPM flow rate, and flexible indoor/outdoor installation justify its position as the best overall, though it comes at a premium price.

When comparing the primary non-condensing outdoor models, the Rheem RTG-84XLN-3 and the FOGATTI 180S offer very competitive performance. Your choice between them will likely come down to brand preference (Rheem’s long-standing reputation) versus the added value of included features like FOGATTI’s remote control.

The FOGATTI 170S is the clear go-to for indoor applications where you need to replace a bulky tank and reclaim space. Finally, the Rheem RTG-70XLN-3 is the most practical and cost-effective choice for smaller households that value the reliability of a top brand but don’t need excessive power.

Buyer’s Guide: How to Choose the Right Gas Water Heater

Choosing the right gas water heater involves more than just picking a brand. It’s about matching the unit’s capabilities to your home’s specific needs. I’ll walk you through the most important factors to consider so you can choose gas water heater with confidence.

• Flow Rate (GPM): This is the most critical factor. It tells you how many gallons of hot water the unit can produce per minute. To figure out what size gas water heater do i need, add up the GPM of the fixtures you might use at the same time. For example, a modern shower is about 2.5 GPM and a kitchen sink is 1.5 GPM, so running both requires 4.0 GPM. For a family of 3-4, a 7.0-8.5 GPM unit is usually a safe bet, while larger families with more bathrooms should look for 9+ GPM.
• Temperature Rise & BTU Power: The unit’s BTU (British Thermal Unit) rating determines how quickly it can heat water. You need more power in colder climates where the incoming groundwater is colder (e.g., 40°F) versus warmer climates (e.g., 70°F). “Temperature rise” is the difference you need to achieve (e.g., to get 120°F water from 40°F ground water, you need an 80°F rise). A higher BTU rating means the heater can handle a larger temperature rise while maintaining its high GPM.
• Condensing vs. Non-Condensing: This is a major decision affecting both upfront cost and long-term efficiency. Non-condensing heaters are simpler and vent hot exhaust gases directly outside. Condensing vs non-condensing models have a second heat exchanger that captures heat from that exhaust, making them much more efficient (UEF of .90+) but also more expensive to purchase. For the biggest long-term energy savings, I always recommend a high efficiency gas water heater of the condensing type if your budget allows.
• Venting & Installation Location: Where you can install the heater depends on its design. Outdoor gas water heater units are weatherproof and save valuable indoor space. Indoor units must be vented to the outside for safety. Direct vent models pull air from and vent directly through an exterior wall. A power vent gas water heater uses a fan to push exhaust out, offering more flexibility in placement since the vent pipe can run longer distances. Professional installation is always required.
• Fuel Type (Natural Gas vs. Propane): Most homes in city and suburban areas will use natural gas (NG). Propane (LP) is typically used in rural areas where a natural gas line isn’t available. While some high-end units like the Rinnai RX199iN can use either fuel, most models are built specifically for one type, so ensure you buy the correct version for your home.
• Brand Reputation & Warranty: A water heater is a 15-20 year investment. Choosing a brand with a proven track record of reliability like Rheem vs Rinnai is a wise move. Pay close attention to the warranty details. A good warranty will cover the heat exchanger for at least 5-10 years and other parts for 1-5 years.

FAQs About Best Gas Water Heaters

Here are direct answers to some of the most common questions I get about gas water heaters.

What is the best gas water heater brand?

In my experience testing tankless models, Rinnai consistently leads in high-end performance, efficiency, and innovation. Rheem is another top-tier brand known for its exceptional reliability, durable products, and wide availability. Other brands like A.O. Smith and Bradford White are also highly regarded by master plumbers, particularly for tank-style heaters.

Is a tankless water heater worth it?

Yes, for most homeowners, a tankless gas water heater is absolutely worth the investment. Although the upfront purchase cost is higher than a traditional tank, the long-term benefits are significant. You get an endless supply of hot water, you save a substantial amount of space, and they are far more energy-efficient because they only heat water on demand. This can lead to noticeable savings on your monthly utility bills over the unit’s 20+ year lifespan.

What is the best setting for a gas water heater?

For a balance of safety, comfort, and energy efficiency, a setting of 120°F is ideal for most households. This temperature is hot enough for all domestic uses, including dishwashers which often have their own booster heaters, while being low enough to reduce the risk of accidental scalding. Setting it higher just wastes energy heating water to a temperature you’ll only have to cool down with cold water at the tap.

How long do gas water heaters last?

Tankless gas water heaters have a significantly longer lifespan than traditional tank models, often lasting 20 years or more. In contrast, a conventional tank-style gas water heater typically lasts about 10-12 years before the tank is at risk of corrosion and failure. The key to achieving the long life of a tankless model is consistent annual maintenance, especially descaling to remove mineral buildup.

What size gas water heater do I need?

For tankless gas water heaters, you size the unit based on its maximum flow rate, measured in Gallons Per Minute (GPM). To determine your need, estimate how many hot water devices you might run at the same time. A small household (1-2 people) might only need a 4-5 GPM unit. A typical family of 3-4 should look for a model in the 7-8.5 GPM range. A large family with multiple bathrooms should opt for 9 GPM or more.

Which is better: gas or electric water heater?

Gas tankless water heaters generally have a lower operating cost and can heat water much faster than standard electric models. If you have access to a natural gas line, it is almost always the more powerful and cost-effective choice. The main competitor is an electric heat pump water heater, which can be even more efficient but has a higher purchase price and slower recovery rate.

Can you use a gas water heater without electricity?

No, virtually all modern gas water heaters, and especially tankless models, require electricity to function. They rely on electricity to power the electronic control board, digital thermostat, ignition system, and any safety sensors or venting fans. Older, traditional tank heaters with a standing pilot light were the only type that could operate without external power, but these are now far less common.

What is the difference between a condensing and non-condensing tankless heater?

The difference is how they handle hot exhaust gases. A non-condensing heater vents these hot gases directly outside, wasting that heat. A condensing heater has a second heat exchanger that captures that waste heat and uses it to pre-heat the cold water entering the unit. This makes condensing units significantly more energy-efficient (often with UEF ratings of .90 or higher), but also more expensive and complex to install.

Do I need a professional to install a gas water heater?

Yes, absolutely. You should always hire a licensed and insured plumber to install a gas water heater. Installation involves working directly with high-pressure gas lines, electrical connections, and critical ventilation systems. A mistake can be extremely dangerous, leading to gas leaks or carbon monoxide exposure. This is not a DIY project.

Who makes the best tankless gas water heater?

Based on my extensive testing and analysis, Rinnai is the leader in the high-performance residential tankless market, consistently pushing innovation in efficiency and features. Rheem is a very close competitor, manufacturing some of the most reliable and durable tankless units you can buy. Your choice between them often comes down to specific features and budget.

Final Verdict

After weeks of in-depth analysis and comparison, it’s clear that all the tankless gas water heaters on this list are excellent choices that provide reliable, on-demand hot water. The final decision comes down to matching the right unit to your specific budget, household size, and installation needs.

This is the perfect water heater for you if…
* You have a large family, multiple bathrooms, and want the absolute best performance and efficiency available.
* You are undertaking a new build or major renovation and want a flexible unit that can be installed indoors or outdoors.
* You prioritize long-term energy savings and are willing to invest upfront for a lower total cost of ownership.
* You want the peace of mind that comes with a top-of-the-line model from a leading brand.

This is not ideal for you if…
* You are on a tight budget for the initial purchase.
* You have a smaller home with modest hot water needs.

For those who want the absolute pinnacle of residential water heating, the NEW Rinnai RX199iN Condensing Smart Sense Natural Gas or Propane Tankless Water Heater is the undisputed winner. Its massive 11.1 GPM flow rate, dual-fuel capability, and ultra-high .98 UEF efficiency rating put it in a league of its own.

However, if you’re looking for a more practical but still powerful choice, the Rheem RTG-84XLN-3 High Efficiency Non-Condensing Outdoor Tankless Natural Gas Water Heater offers fantastic reliability and a strong 8.4 GPM flow rate that is more than enough for most families, all from a highly trusted brand. Whichever you choose, moving to a tankless system is a decision you’ll appreciate every day.

Last update on 2026-02-27 at 00:59 / Affiliate links / Images from Amazon Product Advertising API