Best Gas Water Heaters Consumer Reports: Practical Features for Easier Everyday Use

A strong gas water heater delivers enough flow for your peak fixtures while matching your home’s venting, installation space, and fuel setup. This roundup suits homeowners replacing a tank, planning an indoor installation, or needing continuous hot water for several simultaneous fixtures. The 10 models range from compact 4.3- to 5-GPM units for smaller demands to 7.9-, 8.4-, and 10.3-GPM options for larger households.

Key differences include condensing versus non-condensing designs, indoor versus outdoor placement, natural-gas or convertible fuel compatibility, temperature controls, and built-in protections. Use the listed GPM and BTU figures as starting points, then confirm local code, gas-line capacity, venting, and installation requirements before choosing a model.

The strongest choices depend on installation and peak demand. Rheem’s 8.4-GPM outdoor non-condensing model suits homes that can place the heater outside, while its 8.4-GPM indoor condensing model fits users prioritizing higher listed efficiency and direct venting. Rinnai’s RX130iN adds indoor-or-outdoor flexibility and natural-gas or propane compatibility.

For lower demand, APUS, ThermoMate, and Heatrova offer 4.3- to 6.8-GPM options. Westinghouse adds Wi-Fi and voice control, while MIZUDO offers the highest listed flow at 10.3 GPM.

Gas Tankless Water Heater Comparison

Image	Product	Buy
Best Pick 1	Rheem RTG Series 8.4 GPM Natural Gas Tankless Water Heater Outdoor | 180,000 BTUs High Efficiency On Demand, Continuous Hot Water | Non-Condensing Best for: Outdoor Installation Brand: Rheem | Capacity: 8.4 gallons	View on Amazon
Best Pick 2	Westinghouse Tankless Water Heater Gas Indoor, 7.9 GPM, 180,000 BTU Best for: Compact Indoor Use Brand: Westinghouse | Color: Grey 79NI	View on Amazon
Best Pick 3	Rheem RTGH Series 8.4 GPM Natural Gas Tankless Water Heater Indoor | 157,000 BTUs Super High Efficiency On Demand, Continuous Hot Water | Condensing Ultra-Low Nox Best for: High Efficiency Indoor Brand: Rheem | Capacity: 8.4 gallons	View on Amazon
Best Pick 4	Rinnai RX130iN Condensing Smart Sense Tankless Water Heater Best for: Smart Home Integration Brand: Rinnai | Capacity: 60 cubic inches	View on Amazon
Best Pick 5	APUS Natural Gas Tankless Water Heater, 95,000 BTU, 4.42 GPM Indoor Best for: Small Apartment Use Brand: APUS | Capacity: 4.42 gallons	View on Amazon

How We Compared These Products

We compared dimensions, capacity, materials, compatibility, included components, and care requirements across many Amazon listings. These details matter because the product must fit the available space, intended use, setup requirements, and maintenance routine. After examining the wider field, we selected 10 products from Rheem, Westinghouse, Rinnai, APUS, thermomate, GASLAND, Heatrova, and MIZUDO.

The shortlist includes products such as Rheem RTG Series 8.4 GPM Natural Gas Tankless Water Heater Outdoor, Westinghouse Tankless Water Heater Gas Indoor, and Rinnai RX130iN Condensing Smart Sense Tankless Water Heater. Every recommendation is tied to information stated for that specific product; unclear or missing features were treated as unknown rather than filled with assumptions.

Detailed Reviews: Best Gas Water Heaters Consumer Reports

1. Rheem RTG Series 8.4 GPM Natural Gas Tankless Water Heater Outdoor | 180,000 BTUs High Efficiency On Demand, Continuous Hot Water | Non-Condensing

Best for: Outdoor whole-house continuous hot water.

This Rheem RTG Series tankless water heater provides endless instant hot water on demand for whole-house residential use. Its 8.4 GPM capacity at a 35°F temperature rise delivers 180,000 BTUs, ensuring you never run out of hot water.

With an 0.82 Uniform Energy Factor (UEF), this non-condensing gas tankless water heater saves up to 34% on energy costs compared to electric tank heaters. The outdoor installation design eliminates the need for venting, simplifying placement. Its Hot Start Programming keeps the unit ready, minimizing wait times for hot water.

Product Details

Pros

• Endless hot water on demand
• 8.4 GPM for 3-4 simultaneous showers
• Outdoor installation simplifies venting
• Energy efficient with 0.82 UEF

Cons

• Non-condensing model may be less efficient than condensing units.

Ideal for homes needing continuous hot water outdoors. Ensure proper ventilation considerations for non-condensing units if installing near occupied spaces.

2. Westinghouse Tankless Water Heater Gas Indoor, 7.9 GPM, 180,000 BTU

Best for: Smart control whole-house hot water.

The Westinghouse tankless water heater delivers up to 7.9 GPM and 180,000 BTU, providing enough capacity for three showers simultaneously. Enjoy hot water on demand for all your household needs, controllable via a smart WiFi app or voice commands.

This indoor natural gas unit offers smart WiFi and app control, allowing you to adjust temperature settings from anywhere. Its 7.9 GPM flow rate ensures ample hot water for showers, laundry, and dishwashing. The LED display and overheat protection add to its user-friendly and safe operation.

Product Details

Pros

• Smart WiFi and app control
• 7.9 GPM for multiple simultaneous uses
• 180,000 BTU heating capacity
• Indoor installation with LED display

Cons

• Specific GPM output may vary based on incoming water temperature.

Best for tech-savvy households seeking convenient, on-demand hot water. Ensure your home's natural gas line can support the 180,000 BTU output.

3. Rheem RTGH Series 8.4 GPM Natural Gas Tankless Water Heater Indoor | 157,000 BTUs Super High Efficiency On Demand, Continuous Hot Water | Condensing Ultra-Low Nox

Best for: Ultra-high efficiency indoor condensing.

Experience continuous hot water with the Rheem RTGH Series, featuring 8.4 GPM and 157,000 BTUs for whole-house use. Its industry-leading condensing technology achieves a 0.93 Uniform Energy Factor (UEF) for ultra-low gas bills.

This indoor condensing tankless water heater is ideal for 3-4 simultaneous showers, perfect for large families. The ultra-low NOx emissions comply with environmental standards. Its Super High Efficiency design uses up to 34% less energy than a 50-gallon tank heater, and features Hot Start Programming to eliminate cold water bursts.

Product Details

Pros

• Super high efficiency (0.93 UEF)
• 8.4 GPM for large households
• Ultra-low NOx emissions
• Indoor installation with direct vent

Cons

• Condensing models require a condensate drain.

Requires proper venting and a condensate drain for indoor installation. Confirm its stated fit, dimensions, compatibility, and included components against the intended setup before choosing it.

4. Rinnai RX130iN Condensing Smart Sense Tankless Water Heater

Best for: Convertible indoor/outdoor smart gas.

The Rinnai RX130iN tankless water heater offers versatile installation, suitable for indoors or outdoors with its Versa Vent system. Powered by natural gas or propane, its Smart Sense gas control system adapts to your fuel source.

This compact, condensing unit provides up to 7.1 GPM, ensuring hot water is always available. Its Super-High Efficiency Plus (UEF .97) design optimizes energy use. The Smart Sense technology allows for flexible fuel operation, and periodic maintenance is simplified with an efficient flushing procedure.

Product Details

Pros

• Indoor or outdoor installation flexibility
• Operates on natural gas or propane
• High efficiency (UEF .97)
• Compact suitcase size

Cons

• Outdoor installation requires an RX-OVC vent cap.

Perfect for various installation locations and fuel types. Consider the need for an outdoor vent cap if choosing an outdoor setup.

5. APUS Natural Gas Tankless Water Heater, 95,000 BTU, 4.42 GPM Indoor

Best for: Compact 4.42 GPM natural gas.

The APUS Natural Gas Tankless Water Heater offers a flow rate of 4.42 GPM with a 95,000 BTU output, designed for indoor use. Its compact dimensions make it suitable for space-saving installations.

This unit provides on-demand hot water with a 4.42 GPM capacity, suitable for smaller households or single-fixture applications. It operates on natural gas and includes necessary components for installation. The 35-watt power consumption is energy efficient for its size.

Product Details

Pros

• Compact design for space saving
• 4.42 GPM flow rate
• 95,000 BTU heating capacity
• Indoor installation

Cons

• Lower GPM may not support multiple simultaneous fixtures.

A good choice for apartments or smaller homes needing efficient, on-demand hot water for limited use. Ensure the 4.42 GPM meets your household's peak demand.

6. ThermoMate CZ422NG, Natural Gas Tankless Water Heater Indoor, Up to 5 GPM

Best for: 5 GPM indoor natural gas with safety features.

The ThermoMate CZ422NG is an indoor natural gas tankless water heater delivering up to 5 GPM. It features multiple integrated safety protections for reliable operation, including anti-freezing and flame failure protection.

This unit heats water directly on demand, avoiding storage tank limitations. With a 5 GPM capacity, it's suitable for moderate hot water needs. The integrated error code indicator aids in troubleshooting, while features like dry combustion protection ensure safe operation.

Product Details

Pros

• Up to 5 GPM flow rate
• Integrated safety features
• Anti-freezing protection
• Error code indicator for diagnostics

Cons

• May require professional installation for optimal performance.

Ideal for households needing up to 5 GPM for everyday use. Ensure proper sizing based on peak demand and consider professional installation.

7. APUS Natural Gas Tankless Water Heater, 140,000 BTU, Up to 6.8 GPM, Indoor

Best for: Instant 6.8 GPM natural gas.

The APUS Natural Gas Tankless Water Heater provides instant hot water with a 6.8 GPM flow rate and 140,000 BTU burner. Its exclusive zero cold water technology eliminates waiting for hot water.

Featuring an oxygen-free copper heat exchanger and intelligent heating technology, this indoor unit delivers hot water in just one second. The 6.8 GPM capacity is suitable for multiple simultaneous uses. It comes with installation accessories including zero cold water piping.

Product Details

Pros

• Instant hot water in 1 second
• 6.8 GPM flow rate
• Zero Cold Water Tech
• 140,000 BTU burner

Cons

• Requires a 120V electrical outlet for operation.

Best for homes seeking rapid, continuous hot water with advanced cold water elimination. Ensure adequate gas supply for the 140,000 BTU output.

8. GASLAND Gasmart E 199,000 BTU Tankless Water Heater, Up to 7.6 GPM, CSA Certified Whole House Natural Gas Indoor Installation Residential On-demand Instant Hot Water Heater, CE686NG

Best for: CSA Certified 7.6 GPM whole house.

The GASLAND Gasmart E tankless water heater offers unlimited hot water on demand with up to 7.6 GPM. CSA Certified, it meets high safety standards for reliable residential use in whole-house applications.

This compact, wall-mounted unit provides continuous hot water for showers, laundry, and dishes without interruption. Its energy-efficient design saves space and offers comfort. Safety features include anti-freezing, dry combustion, and flame failure protection, ensuring dependable operation.

Product Details

Pros

• Unlimited hot water on demand
• CSA Certified for safety
• 7.6 GPM flow rate
• Compact and space-saving design

Cons

• Wattage listed as 52 KW may be a typo; typically lower for residential gas units.

Suitable for homes needing consistent, high-volume hot water and prioritizing safety certifications. Verify wattage specifications for accurate power requirements.

9. Natural Gas Tankless Water Heater Indoor,HeatRova 4.3 GPM 102,000 BTU,Instant Hot Water,Constant Temperature,Pure Copper Heat Exchanger,3/4″ NPT Connector,Energy-Saving,On-Demand for 3–4 Fixtures

Best for: 4.3 GPM constant temperature indoor.

The Heatrova indoor natural gas tankless water heater delivers instant hot water on demand with a 4.3 GPM flow rate and 102,000 BTU capacity. Its intelligent constant temperature control maintains precise water temperatures.

Equipped with advanced temperature regulation and Constant Temperature PLUS technology, this unit provides endless hot water for 3-4 fixtures simultaneously, ideal for larger homes. The pure copper heat exchanger ensures durability and efficient heat transfer. It includes multiple safety features for indoor use.

Product Details

Pros

• Intelligent constant temperature control
• 4.3 GPM for 3-4 fixtures
• Pure copper heat exchanger
• Indoor installation safety features

Cons

• May not be sufficient for very high simultaneous demand.

A good option for larger homes seeking consistent temperature and on-demand hot water for multiple fixtures. Ensure the 4.3 GPM meets your peak usage needs.

10. MIZUDO Natural Gas Tankless Water Heater, 199,000 BTU, Indoor

Best for: 10.3 GPM whole-house high-temp.

The MIZUDO Natural Gas Tankless Water Heater boasts a high input of 199,000 BTU, supporting up to 10.3 GPM for simultaneous hot water demand across multiple bathrooms and appliances.

This indoor unit is an ideal upgrade from traditional 50-gallon tanks for busy households, handling 2-3 bathrooms, kitchen faucets, and dishwashers. Its advanced gas modulation maintains water temperature within ±1°F, up to a high of 149°F, ensuring precise temperature control.

Product Details

Pros

• High 10.3 GPM flow rate
• ±1°F precise temperature control
• Up to 149°F high-temperature output
• 199,000 BTU heating input

Cons

• Requires a 120V electrical connection for operation.

Excellent for large, busy households needing high-volume, precisely controlled hot water. Ensure adequate gas line capacity for the 199,000 BTU input.

What Buyers Often Overlook

Sizing gas tankless water heaters by simultaneous demand

Choose the flow rating by adding the fixtures you may use at the same time, not by counting bathrooms alone. The supplied models span 4.3 GPM for Heatrova, 4.42 GPM for APUS, 5 GPM for ThermoMate, 6.8 GPM for APUS, 7.1 GPM for Rinnai, 7.6 GPM for GASLAND, 7.9 GPM for Westinghouse, 8.4 GPM for both Rheem units, and 10.3 GPM for MIZUDO. Higher listed capacity is better suited to overlapping showers, laundry, dishwashing, and faucets, but actual output depends on temperature rise and installation conditions.

Rheem identifies its 8.4-GPM units as suitable for three to four simultaneous showers, while Westinghouse cites three showers. Heatrova describes its 4.3-GPM model for several fixtures, but its verified details also describe two to three simultaneous fixtures.

Treat those claims as planning guidance and match them to your cold-water temperature and household routine.

The Key Product Trade-Off

Indoor, outdoor, condensing, and fuel compatibility

Installation type is a primary fit decision because these designs require different placement and venting arrangements. Rheem’s RTG-84XLN-3 is an outdoor, non-condensing natural-gas unit, so outdoor placement eliminates indoor venting for that model. Rheem’s RTGH-84DVLN-3 is an indoor condensing natural-gas unit with direct venting.

Rinnai’s RX130iN offers indoor or outdoor installation through Versa Vent and can operate with natural gas or propane through its Smart Sense gas control system; the supplied data notes that an RX-OVC vent cap is required for outdoor installation. Westinghouse, APUS, ThermoMate, GASLAND, Heatrova, and MIZUDO are presented as indoor models in the supplied listings.

Condensing units such as Rheem’s 0.93 UEF model and Rinnai’s 0.97 UEF model emphasize efficiency, while the outdoor Rheem uses a non-condensing design.

Best Gas Water Heaters Consumer Reports: Buyer's Guide

Fit, Dimensions, and Compatibility

Compare the listed dimensions with the intended counter, cabinet, appliance, storage, or installation space. Confirm model compatibility and connection requirements where they are supplied. A useful feature cannot compensate for a product that does not physically fit or work with the buyer’s existing setup.

Capacity, Output, and Operating Format

Match listed capacity, volume, output, and operating mode to the actual household or work routine. Larger figures can support heavier use, while a smaller format may be easier to place and maintain. Treat daily output, immediate storage, and container capacity as separate specifications when the listing distinguishes them.

Materials, Construction, and Care

Use the listed materials and care instructions to judge cleaning effort, storage conditions, and compatibility with the intended use. Dishwasher, freezer, food-contact, or weather-related claims are included only when supplied for that product. Check whether routine care fits the way the product will be used.

Included Components and Setup Needs

Review the included components before planning installation or first use. Hoses, adapters, lids, paddles, bowls, brushes, controls, and manuals vary by listing. Confirm power, water, assembly, or accessory requirements from the supplied product information rather than assuming that separately pictured parts are included.

Which Should You Choose?

Choose the Rheem RTG Series 8.4 GPM outdoor model when outdoor placement and natural gas are practical and you want continuous hot water without indoor venting. Choose the Rheem RTGH Series or Rinnai RX130iN when a condensing design is more important; Rinnai is especially flexible if indoor-or-outdoor placement or natural-gas/propane operation matters. For connected controls, Westinghouse adds Wi-Fi, app, voice control, and ±1°F temperature control.

Smaller households or lighter simultaneous demand can consider the 4.3- to 5-GPM Heatrova, APUS, or ThermoMate units. APUS’s 6.8-GPM model, GASLAND’s 7.6-GPM unit, and MIZUDO’s 10.3-GPM model fit higher-demand planning, subject to verified gas, venting, and code requirements.

Quick Buying Checklist

• Confirm the complete dimensions against the available space.
• Verify model, accessory, connection, and appliance compatibility.
• Match capacity or output to the expected amount of use.
• Compare materials and care instructions with the maintenance routine.
• Check the included components before planning setup or first use.
• Confirm listed power, water, storage, or installation requirements where applicable.

Frequently Asked Questions

What is the typical GPM for these gas tankless water heaters?

GPM (gallons per minute) varies significantly. Some models offer up to 4.42 GPM, suitable for smaller needs, while others provide 7.6 GPM to 8.4 GPM, designed to handle multiple fixtures simultaneously for continuous hot water supply.

How do condensing and non-condensing models differ?

Condensing models are more energy-efficient as they capture extra heat from exhaust gases. Non-condensing units release more heat through the exhaust. Condensing units often have higher efficiency ratings and may require a condensate drain.

What is the role of BTU in tankless water heaters?

BTU (British Thermal Units) indicates the heating power of the unit. Higher BTU ratings, such as 180,000 or 199,000 BTU, mean the water heater can heat water more quickly and support higher flow rates, essential for larger homes or high demand.

Are these tankless water heaters suitable for whole-house use?

Yes, many of these models are designed for whole-house applications. Units with higher GPM ratings and BTU outputs, like those around 7.6 GPM or more, can effectively supply hot water to multiple bathrooms and appliances simultaneously.

What are the installation considerations for indoor gas tankless units?

Indoor installation requires proper ventilation to exhaust combustion gases safely. Ensure adequate airflow and consider the need for a condensate drain if installing a condensing model. Professional installation is often recommended for safety and optimal performance.

Final Words

Selecting the right gas tankless water heater depends on your hot water demands and installation location. For high-demand households, models with higher GPM and BTU ratings are ideal. Consider efficiency and ventilation requirements, especially for indoor units, to ensure optimal performance and safety.