When searching for the best tankless water heater gas, the main considerations are capacity, efficiency, and installation type. The Rinnai RE199iN stands out as the best overall due to its high flow rate and reliable performance. For outdoor setups, the Rheem RTG-95XLN-3 offers excellent efficiency and durability. The challenge lies in balancing upfront cost, long-term savings, and ease of use. Continue reading to see how each option stacks up and which one is right for your needs.
Key Takeaways
- High flow rates are key for large households or simultaneous usage, as seen with the Rinnai RE199iN.
- Outdoor models like the Rheem RTG-95XLN-3 excel in durability and weather resistance, ideal for outdoor installations.
- Wi-Fi control features are increasingly common and add convenience, notably on units like Westinghouse and MIZUDO.
- Efficiency and BTU ratings significantly impact long-term energy costs and suitability for different home sizes.
- Tradeoffs often involve higher upfront costs versus long-term savings, especially with premium models.
More Details on Our Top Picks
Rinnai RE199iN Non-Condensing Natural Gas Tankless Water Heater, Up to 9.8 GPM, Indoor Installation, 199,000 BTU
The Rinnai RE199iN stands out as the best overall choice thanks to its impressive flow rate of up to 9.8 GPM, making it well-suited for larger households with multiple fixtures running simultaneously. Its compact design saves space without sacrificing performance, and the durable heat exchanger backed by a 15-year warranty offers peace of mind. Compared to the Westinghouse model, which also delivers high flow, the RE199iN’s built-in LED display simplifies maintenance and troubleshooting, though it requires an extra WiFi module for remote control. This model is ideal for those prioritizing reliability and ease of use, especially in indoor settings. The tradeoff is that installation is best handled by a professional due to its complexity.
Pros:- High flow rate supports multiple fixtures simultaneously
- Space-saving compact design
- Long-term warranty on heat exchanger
- LED display offers clear service alerts
Cons:- WiFi control requires an additional module (not included)
- Professional installation recommended due to complexity
Best for: Families or households with multiple bathrooms needing reliable, high-capacity hot water support
Not ideal for: Small apartments or single fixtures where a smaller, less powerful unit suffices, as its size and capacity may be overkill
- Flow Rate:Up to 9.8 GPM
- BTU:199,000
- Installation Type:Indoor
- Fuel Type:Natural Gas
- Condensing:Non-Condensing
- Guarantee:15-year heat exchanger, 5-year parts, 1-year labor
Bottom line: This model is best for larger households that need consistent hot water and space efficiency, with the caveat of requiring professional setup.
APUS Natural Gas Tankless Water Heater 140,000 BTU Indoor, Up to 6.8 GPM, Wi-Fi Control
The APUS 140,000 BTU model shines for those seeking remote control and energy efficiency. Its Wi-Fi capability allows users to adjust temperature settings and monitor performance via a mobile app, making it ideal for tech-savvy homeowners. While it offers a lower flow rate of 6.8 GPM compared to the Rinnai, it compensates with smart features like ECO mode and smart cycle, which can reduce energy bills. However, performance may decline in colder climates below 41°F, and installation might be challenging for non-experts, especially in cold regions requiring proper drainage. This unit is best suited for those who value remote management and are prepared for a more complex setup.
Pros:- Remote Wi-Fi control and monitoring
- Supports multiple outlets without temperature fluctuations
- Energy-efficient ECO mode and smart cycle
- Instant hot water with no cold burst
Cons:- Performance may decrease in very cold weather
- Installation can be complex for some users
Best for: Homeowners with moderate hot water needs who want integrated Wi-Fi control and energy savings
Not ideal for: Large households with high simultaneous hot water demands or colder climates where performance could drop
- BTU:140,000
- Flow Rate:Up to 6.8 GPM
- Temperature Range:95°F–140°F
- Dimensions:21.3×13.6×7.1 inches
- Connections:1/2″ NPT
Bottom line: This pick makes the most sense for tech-forward homeowners prioritizing convenience and smart energy management, with some limitations in cold climates.
Rheem RTG-95XLN-3 High Efficiency Outdoor Tankless Natural Gas Water Heater 9.5 GPM
The Rheem RTG-95XLN-3 is tailored for outdoor installation, making it an excellent choice for those who prefer a space-saving solution that doesn’t require indoor venting. It provides up to 9.5 GPM, comparable to the Rinnai, and features hot-start programming that prevents cold water bursts—a significant plus for reliability. While it offers high efficiency and robust performance for homes with 2-3 bathrooms, its outdoor-only design limits versatility—it’s not suitable for indoor use. Compared to the indoor models, it eliminates the need for a venting system but demands proper outdoor placement and protection from the elements. This makes it ideal for owners seeking durability and outdoor installation, though it may not meet the needs of larger or more complex indoor setups.
Pros:- High flow rate for multiple fixtures
- Durable outdoor design
- Hot-start programming prevents cold bursts
- Easy wall mounting
Cons:- Limited to outdoor installation
- Requires professional setup
Best for: Homeowners wanting a high-capacity, outdoor-ready water heater for space-saving installation
Not ideal for: Indoor-focused households or those in climates with extreme weather without proper outdoor protection
- Flow Rate:9.5 GPM
- BTUs:199,900
- Fuel Type:Natural Gas
- Installation:Outdoor
- Features:Hot-start programming
Bottom line: This outdoor model is best for those who need a reliable, high-flow unit outside, but it’s not suitable for indoor spaces or extreme climates without protection.
Westinghouse Natural Gas Tankless Water Heater Indoor – 7.9 GPM, 180,000 BTU, Wi-Fi Enabled, Self-Modulating, High Efficiency
This Westinghouse model stands out for combining high capacity with smart features, making it an excellent choice for larger households or small commercial settings. Its 7.9 GPM flow rate surpasses many indoor units like the Rheem RTG-70DVLN-3, offering more hot water on demand. The Wi-Fi control adds convenience, enabling remote temperature adjustments, which is a significant bonus over traditional models. However, its installation complexity and indoor-only requirement mean it’s best suited for those with professional help and suitable space. The 180,000 BTU output ensures quick hot water delivery, but the need for 120V power and professional installation might be drawbacks for some.
Pros:- High flow rate of 7.9 GPM supports multiple fixtures simultaneously
- Wi-Fi enabled for remote temperature management
- Energy-efficient on-demand operation
- Safety certified with freeze protection
Cons:- Requires professional installation, adding cost and complexity
- Indoor installation limits placement options
- Dependent on 120V power supply
Best for: Large families or small commercial setups needing consistent, high-capacity hot water with remote control capabilities
Not ideal for: Homeowners seeking a simple, plug-and-play solution or those with limited indoor space
- Flow Rate:7.9 GPM
- BTU:180,000
- Gas Type:Natural Gas
- Power Supply:120V AC
- Connections:3/4″ NPT
- Installation:Indoor
Bottom line: This model suits large households or commercial users who prioritize capacity and smart control over installation simplicity.
Rheem RTG-70XLP-3 High Efficiency Outdoor Tankless Liquid Propane Water Heater 7.0 GPM, 160,000 BTUs
Compared with the Westinghouse indoor model, the Rheem RTG-70XLP-3 is designed specifically for outdoor installation, saving indoor space and avoiding ventilation issues. Its 7.0 GPM flow rate is suitable for smaller households of 2-3 bathrooms, but may fall short for larger families needing more hot water. This unit’s outdoor durability and simple design make it ideal for those looking to avoid indoor installation hassles, though it limits use to external spaces and requires professional setup. Hot-start programming and high efficiency enhance user experience, but its outdoor-only use and slightly lower capacity make it less versatile for bigger households.
Pros:- Outdoor installation saves indoor space
- Reliable hot water during peak demand
- Durable, weather-resistant construction
- Hot-start programming prevents cold bursts
Cons:- Limited to outdoor environments
- Flow rate may be insufficient for large households
- Requires professional installation
Best for: Homeowners with small to medium household hot water needs who prefer outdoor installation and space-saving design
Not ideal for: Large households or those living in cold climates needing higher flow rates or indoor units
- Flow Rate:7.0 GPM
- BTUs:160,000
- Fuel Type:Liquid Propane
- Installation Type:Outdoor
- Suitable for:2-3 bathroom homes
Bottom line: This outdoor LP gas heater suits smaller homes seeking space efficiency and outdoor durability over maximum capacity.
MIZUDO 199K BTU Tankless Gas Water Heater, 10.3 GPM, Indoor, WiFi & App Control, Constant Temp, High Efficiency
The MIZUDO 199K BTU model delivers a robust 10.3 GPM, making it ideal for large households or homes with multiple fixtures. Its smart WiFi and app control provide a level of convenience not found in many traditional units, similar to the Westinghouse but with a higher flow rate for demanding households. The sealed combustion system and safety features add peace of mind, although the complex installation and higher cost may deter casual users. Compared to the Rheem RTG-70XLP-3, it offers significantly more hot water, but its size and professional installation requirements make it less suitable for small or straightforward setups.
Pros:- High flow rate supports multiple fixtures simultaneously
- WiFi & app control for remote management
- Sealed combustion for safety and efficiency
- Durable corrosion-resistant components
Cons:- Requires natural gas connection and wall mounting
- Higher initial investment
- Complex installation process
Best for: Large families or households with high simultaneous hot water demand seeking smart, reliable control
Not ideal for: Small households or those with limited installation options, due to size and complexity
- Flow Rate:10.3 GPM
- BTUs:199,000
- Maximum Temperature:149°F
- Heat Output:199,000 BTU/hr
- Voltage:120V
- Wattage:44W
Bottom line: This pick is best for large households needing high capacity and remote management with smart features.
Rheem RTG-70DVLP-3 High Efficiency Indoor Tankless Liquid Propane Water Heater 7.0 GPM, 160,000 BTUs
The Rheem RTG-70DVLP-3 earns a spot for its ability to deliver continuous hot water for homes with 2-3 bathrooms, outperforming smaller models like the APUS 140,000 BTU in flow rate and hot-start features. Compared with natural gas options like the Rinnai RE199iN, this propane model offers a high heat output suitable for moderate-sized households. Its space-saving wall-mounted design is a big plus, but it requires professional installation and is limited to indoor use—making it less suitable for outdoor or DIY setups. The flow rate of 7 GPM might fall short for larger households with multiple simultaneous fixtures, but it remains a reliable choice for most typical homes.
Pros:- Provides continuous hot water for multiple fixtures
- Space-saving wall-mounted design
- Features hot-start programming and leak detection for safety and reliability
Cons:- Requires professional installation, which adds upfront cost
- Limited to indoor installation, not suitable for outdoor use
- Flow rate may be inadequate for larger households with high demand
Best for: Homeowners with 2-3 bathrooms seeking reliable, space-efficient hot water supply on propane
Not ideal for: Large families or homes with high simultaneous hot water demand, as the 7 GPM flow rate may be insufficient
- Power Source:Liquid Propane
- Flow Rate:7 Gallons Per Minute
- Maximum Temperature:140°F
- Heat Output:160,000 BTUs
- Efficiency:0.82
- Mount Type:Wall
Bottom line: This heater suits smaller households needing dependable hot water in limited space, but not ideal for larger families or outdoor setups.
How We Picked
These products were evaluated based on performance, installation versatility, build quality, and user control options. I prioritized models with high flow rates, energy efficiency, and reliable brand reputation. Cost was a factor, but long-term value and ease of use carried greater weight. The ranking reflects a balance between capacity, features, and overall reliability, ensuring options for different household sizes and budgets.Factors to Consider When Choosing Best Tankless Water Heater Gas
Choosing the best gas tankless water heater involves understanding several key factors beyond just capacity. Size and flow rate determine if the unit can meet your household’s hot water demand without lag. Efficiency impacts long-term energy costs, especially in colder climates where the incoming water temperature is lower. Installation type—indoor or outdoor—affects durability and placement options. Maintenance needs and control features, such as Wi-Fi, can also influence convenience and ongoing costs. Being aware of these broader considerations helps avoid costly mistakes and ensures you select a model that truly fits your household’s needs.Flow Rate and Capacity
Flow rate, measured in gallons per minute (GPM), is one of the most critical factors. Larger households or homes with multiple fixtures running simultaneously require higher GPM ratings, typically above 8 GPM. Choosing a unit with insufficient capacity results in inconsistent hot water or cold shocks. Conversely, overshooting capacity can lead to unnecessary costs. Matching your household’s peak hot water demand with the right flow rate ensures comfort without overspending on excessive capacity.
Energy Efficiency and BTU Rating
Energy efficiency impacts how much you’ll pay over time, especially with frequent use. Look for models with high efficiency ratings and proper BTU sizing; a unit that’s too powerful can waste energy, while one that’s underpowered struggles to meet demand. Outdoor units often have weather-resistant features that improve efficiency in cold climates. Balancing BTU output with your climate and usage patterns helps optimize both performance and savings.
Installation Location: Indoor vs. Outdoor
Deciding between indoor and outdoor installation affects unit choice and durability. Indoor models, like the Rinnai RE199iN, typically require venting and have a higher initial cost but offer aesthetic flexibility. Outdoor units must withstand weather elements and are generally more durable, making them ideal for harsh climates. Proper placement ensures optimal operation and minimizes maintenance. Considering your home’s layout and climate is essential for choosing the right installation type.
Control Features and Connectivity
Modern units increasingly offer Wi-Fi and app controls, allowing for remote temperature adjustments and maintenance alerts. These features can add convenience but may come with higher upfront costs. They are especially beneficial for busy households or those who want to fine-tune their hot water system. However, ensure that the added features are compatible with your existing smart home setup, and weigh their benefits against the extra expense.
Cost, Maintenance, and Longevity
Initial purchase price often correlates with features and capacity, but long-term maintenance costs and durability are equally important. Premium models tend to have longer warranties and better build quality, reducing repair costs down the line. Proper maintenance, like flushing and filter checks, extends lifespan and efficiency. Balancing upfront costs with expected longevity ensures you choose a model that offers better value over its service life.
Frequently Asked Questions
How do I know what size tankless water heater I need?
To determine the right size, consider your household’s peak hot water demand. Calculate how many fixtures will run simultaneously, such as showers, dishwashers, and laundry. Flow rate is key; for example, if you need to run two showers and a dishwasher at once, look for a model with at least 8-10 GPM. Matching the unit’s capacity with your household needs prevents cold water shocks and ensures reliable hot water supply.
Are outdoor gas tankless water heaters reliable in cold climates?
Outdoor models like the Rheem RTG-95XLN-3 are designed to withstand weather elements, but very cold climates may require additional protection such as insulation or a weatherproof enclosure. Some units perform better in low temperatures due to their design and weather-resistant features. If you live in an extremely cold area, consider a model with a high BTU rating and built-in frost protection to maintain consistent performance.
Is Wi-Fi control worth the extra cost?
Wi-Fi features offer convenience, allowing remote temperature adjustments, diagnostics, and maintenance alerts. For busy households or tech-savvy users, this can translate into better control and fewer surprises. However, if your household prefers simple, straightforward operation, a basic model without connectivity may be sufficient. Weigh the added convenience against the upfront cost and potential complexity of setup.
How often does a gas tankless water heater need maintenance?
Regular maintenance, like flushing to remove mineral buildup and inspecting vents, is recommended annually or biannually. Proper upkeep ensures consistent performance and extends lifespan, with most units lasting 15-20 years. Neglecting maintenance can lead to efficiency loss and costly repairs. Choosing a model with accessible service points simplifies ongoing upkeep and minimizes downtime.
Can I install a gas tankless water heater myself?
Installation involves gas line connections, venting, and plumbing, which typically require a licensed professional. Incorrect installation can lead to safety hazards, inefficiency, or voided warranties. It’s best to hire a qualified technician familiar with local codes and regulations. While some experienced DIYers may handle minor upgrades, a professional installation is generally the safest approach for gas units.
Conclusion
For most households seeking all-around reliability and performance, the Rinnai RE199iN offers excellent value as the best overall pick. Those prioritizing outdoor durability and weather resistance will find the Rheem RTG-95XLN-3 to be the best choice. Budget-conscious buyers should consider models like the Westinghouse or MIZUDO for good performance at a lower cost. If you’re new to tankless systems, a model with simple controls and straightforward installation makes sense. For larger homes or demanding setups, investing in higher capacity or premium features can deliver better long-term satisfaction.
