Best Tankless Gas Water Heater | Reviews

Best Tankless Gas Water Heater Reviews

Tired of running out of hot water all the time? Looking to save on your utility bill and reduce your carbon footprint? A tankless gas water heater is the perfect option. Tankless gas water heaters produce hot water on demand rather than filling a storage tank. You consume hot water only when you use it, saving space, energy, money, and the environment.

With so many benefits, it’s no surprise that gas tankless hot water heaters are also quite popular—and with popularity comes a flooded market. If you’re a bit lost on which model to choose, no worries, we’ve rounded up the best tankless gas water heater, reviewing their features, and the pros and cons of each one. We’ve also thrown together a buyer’s guide further down the article to help make your decision easier. 

Top 5 Best Tankless Gas Water Heaters

When reading our tankless gas water heater reviews, keep in mind that your mileage may vary, these brands and models provide the best features and value for the money, but the best tankless gas water heater for your home will eventually depend on your specific needs.

1. Rheem RTGH-95DVLN Direct Vent Tankless Gas Water Heater

Rheem RTGH-95DVLN 9.5 GPM Indoor Direct Vent Tankless Natural Gas Water Heater


  • High flow rate of 9.5 GPM
  • Energy efficiency rating of 94%
  • Ease of use
  • Safety features
  • Interior installation
  • Works well in cold climates


  • A little on the pricey side
  • Overkill for smaller homes

Overall Rating:

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The Rheem direct vent tankless gas water heater is a top-rated option for homeowners seeking value and performance. It’s often considered the best natural gas tankless water heater on the market. Thanks to a high flow rate of 9.5 GPM, it can support a load of laundry, two showers, and a sink full of dishes simultaneously with continuous hot water—making it perfect for large families.

With Advanced tankless engineering, the Rheem features temperature fluctuation control, an overheat-film wrap for breach protection, and the ability to work in tandem with a second unit if you have additional water needs. It can be vented either indoors or outdoors and runs self-diagnostics to warn you of any system problems.

An ultra-efficient condensing unit extracts heat from exhaust gases, to reduce energy usage and your utility bill. The unit overall boasts an impressive 94% efficiency rating as per third-party testing by the Air Conditioning, Heating, and Refrigeration Institute (AHRI). It’s also high altitude compliant, suitable for cold climates, and includes a digital remote control.

The remote is simplistic, with no more than a power button, and two buttons to turn the water temperature up or down, but it does allow you to adjust the water temperature without accessing the tank itself.

The Rheem RTGH-95DVLN comes with a 10-year warranty on its heat exchanger and a 1-year warranty on parts. It requires a minimum natural gas intake pipe of ¾-inches and uses roughly 199,000 BTUs (around 200 CF) while running. It must be installed indoors.

2. Rinnai RUC98iN Tankless Gas Water heater


  • High flow rate – 9.8 GPM
  • 96% energy efficiency
  • 12-year warranty
  • Dual venting options
  • Low flow rate alert at 0.4 GPM


  • A slight dip in water pressure when supporting multiple users

Overall Rating:

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Rinnai tankless gas water heaters have been in use in Europe and Asia for nearly a century. Rinnai began as a company in 1920 and marketed its products in the US in 1974.

The Rinnai RUC98iN tankless gas water heater installs indoors and doesn’t take up a great deal of space. These units have low CO2 emissions and a high-efficiency rating. The Rinnai RUC98iN tankless gas water heater has a high flow rate and supports a family of four or more using multiple fixtures simultaneously. However, users will notice a slight dip in water pressure with multiple users. There is also a low flow rate alter to prevent system damage in the event of a malfunction.

You can use either concentric or PVC venting for easy vent installation. Recirculation technology, combined with additional venting, allows for a high flow rate of 9.8 GPM with a consistent temperature. It also has frost protection, making it suitable for colder climates.

The Rinnai RUC98iN tankless gas water heater is a non-condensing unit that still manages only to lose 4% of the heat generated to the atmosphere (96% efficient). A tankless gas water heater with that degree of efficiency could potentially save you 30% on your gas bill compared to a conventional water heater—a figure many natural gas tankless water heater reviews confirm.

Rinnai is generous with its 12-year warranty that covers most material defects. Some water heaters won’t last that long. If you have a high-demand household for hot water (e.g., multiple teenagers) and live in a cold climate, the Rinnai RUC98iN tankless gas water heater easily earned its spot among the best tankless gas water heater.

3. Takagi T-H3-DV-N Tankless Gas Water Heater


  • 10 GPM flow rate
  • 95% energy efficient
  • 15-year warranty
  • Small installation footprint


  • Slow to provide hot water at first
  • Temperature drops during the initial use of multiple devices
  • Expensive installation possible if retrofitting gas and water lines required in your home

Overall Rating:

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The Takagi T-H3-DV-N is an energy and thermally efficient indoor unit capable of producing 10 gallons of hot water per minute. The GPM rate can support up to four bathrooms simultaneously. It is a condensing gas tankless water heater that provides quiet operation when in use.

This tankless gas water heater has low nitrogen oxide emissions, high energy conversion features, and self-monitored heating. It is 95% energy efficient, among the most highly rated tankless gas water heaters available today. It is then, of course, Energy Star compliant.

While it is an indoor model, it has a relatively small footprint at 11.2 x 17.8 x 24.9 inches, making it one of the smallest tankless gas water heaters in its class. It features advanced controls and durable, corrosion-resistant construction backed by a 10-year limited warranty for the commercial model and a 15-year limited warranty for the residential model. The heat exchanger, a high-wear part, comes with a 6-year limited warranty. Both models feature a 5-year limited parts warranty.

The Takagi T-H3-DV’s energy efficiency and use of natural gas can help reduce your long-term energy costs. They are durable, long-lasting tankless gas water heaters that potentially last up to 20 years or more.

It’s recommended to consult with a professional installer for the Takagi T-H3-DV tankless gas water heater, which is a cost factor. Combustion venting is required, as well as some additional hardware for installation. Long-term savings can likely offset installation costs, though.

However, the Takagi T-H3-DV can significantly reduce your hot water energy costs and is a compact, high-performance tankless gas water heater with an impressive set of manufacturer warranties for years of uninterrupted service.

4. Noritz NRC66DVNG Tankless Gas Water Heater

Noritz NRC66DVNG Best Tankless Gas Water Heater


  • 93% energy efficient
  • Small footprint
  • 12-year warranty
  • Ease of installation


  • Cost
  • Only suitable for smaller homes


Overall Rating:

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The Noritz company has been making and selling some of the best gas tankless water heaters for over 60 years. Promoted for their compact design and ease of installation in small homes or apartments, the Noritz NRC66DVNG is an indoor tankless gas water heater that is energy efficient and low NOx emitting.

It can be installed to use direct or non-direct venting (with an additional conversion kit). The Noritz NRC66DVNG is a condensing tankless gas water heater installed without a high-temperature vent. It is 93% energy efficient and will run on either natural gas or propane.

You can use PVC piping for ventilation, which must be purchased separately. The Noritz NRC66DVNG has a small footprint at 6.7 x 13.8 x 23.6 inches. The flow rate of 6.6 GPM will accommodate two users simultaneously, making the Noritz NRC66DVNG ideal for smaller homes or apartments. Its high-altitude mode and propane compatibility make it an excellent candidate for small mountain homes.

It features overheating and freeze prevention technology to prevent weather-related complications. A flame sensor and direct electronic ignition make keeping the pilot lit a breeze, too.

The Noritz NRC66DVNG is available with either stainless steel or copper heat exchangers, which are resistant to corrosion and comes encased in a durable steel casing with a polyester coating. It comes with a 12-year warranty on the heat exchanger, a 5-year warranty on parts, and a one-year warranty on labor.

The Noritz NRC66DVNG’s low flow rate might make you consider other gas tankless water heaters if your hot water capacity needs exceed two faucets simultaneously. However, for a smaller home that uses either natural gas or propane, the Noritz NRC66DVNG is one of the best instant water heaters. It is a feature-rich tankless gas water heater that can provide long-term energy savings.

5. Rinnai RL Series HE+ Tankless Gas Water Heater


  • Optional WiFi, remote monitoring, and diagnostics
  • Electronic ignition
  • 12-year heat exchanger warranty


  • Slow to provide hot water at first
  • The condensing model is more expensive
  • Installation difficult – requires professional assistance


Overall Rating:

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The final model in our collection of tankless gas water heater reviews is the Rinnai RL Series HE+. This unit runs on either natural gas or propane, has a high flow rate, can be installed indoors or outdoors, and comes certified for manufactured (mobile) homes.

The Rinnai RL Series HE+ has an 81% energy efficiency rating, is Energy Star compliant, and is approved for high altitude use. It has a flow rate of 9.8 GPM and will accommodate up to five bathrooms simultaneously. This unit is available in condensing and non-condensing models. The Rinnai RL Series HE+ can save energy costs and has a rich set of features.

It’s compact space-saving design and optional WiFi module for remote monitoring and management, make it easy to tuck away in an unobtrusive corner. Advanced safety features such as flame failure protection and automatic frost protection ensure you won’t have to worry about this unit becoming a safety hazard.

The Rinnai RL Series HE+ tankless gas water heater has a footprint of 14.04 x 22.95 x 9.27 inches. Its high-capacity flow rate, energy efficiency, potential energy savings, and flexible installation options make it a serious contender for a replacement water heater.

It has a 12-year warranty on the heat exchanger, a five-year parts warranty, and a one-year warranty on labor (residential installations, only). The Rinnai RL Series HE+ has an environmentally friendly design with low CO2 and NOx emissions, and a durable projected 20-year life span, making it an excellent selection for your home or business. It also comes with a valve kit.

Water Heater Buying Guide

If you’re like the average homeowner, hot water is your home’s second-largest energy expense after heating and cooling. Many homes built in the last 70 years have storage tank water heaters built with varying degrees of energy efficiency. These older water heaters can only provide hot water for so long, depending on capacity and the number of consecutive showers needed on a typical morning in your household.

Most people don’t think about their water heater (or that portion of their energy bill) until something’s wrong with it. If it’s looking like time to replace your existing water heater, you’ll be pleased to know that federal regulations require greater energy efficiency from water heaters than they did 20 years ago. Tankless (on-demand) water heaters are among the most energy-efficient water heaters available.

Generally, most homeowners replace their existing water heater with the same type of water heater using the same energy source—electricity or natural gas. You can switch to an on-demand water heater, but the installation costs for retrofitting plumbing or electrical may be a consideration. For new home construction, additions, or remodeling, it may make sense to install a tankless on-demand water heater from the outset.

Having a continuous flow of hot water for consecutive showers, doing laundry and dishes simultaneously, accommodating your family’s peak morning hot water demands, or just taking a long shower doesn’t have to be a luxury. The best on-demand water heaters are affordable and can save you money on energy and water costs in the long run.

Homeowners who are replacing their existing water heaters will need to factor the purchase price, annual energy cost, and the estimated installation cost to determine how long before they will begin to recoup the cost of their water heater replacement. Payback times are generally longer for water heater replacements than for new construction.

What to Consider When Buying a Gas Tankless Water Heater

How do you decide which is the best tankless gas water heater? There are several features to consider when selecting a new water heater. The majority of top-rated tankless water heater models have similar performance, but some key features may be a differentiator for you when choosing your next water heater.

1. Capacity or Flow Rate

Storage tank water heaters hold anywhere from 40 to 55 gallons or more of hot water. What size you buy depends on the number of persons living in your home, the number of appliances using hot water, and your overall peak hot water usage.

Tankless gas water heaters have very little capacity, but the real measure of tankless water heaters is flow rate—how many gallons per minute (GPM) a tankless water heater produces. A high-capacity tankless water heater produces 9-10 GPM, which is suitable for the simultaneous use of three to five water sources. Lower-capacity models, however, often cost less—don’t assume bigger is better. Your goal is to find the best on-demand water heaters that meet or slightly exceeds the needs of your projected household. 

2. Form Factor 

A water heater’s form factor is a consideration as well. Newer storage tank water heaters are often broader and taller than their older counterparts due to having more insulation and other improvements and thus may not fit in the same space as your old water heater. The size of a water heater highly depends on the type of water heater which in turn is decided by its hardware. 

Tankless gas water heaters have a much smaller form factor than a storage-tank water heater and can easily fit into most spaces formerly occupied by your old water heater with ease. Though it is important to ensure the space is suitable for your desired model. For instance, an exterior cabinet with little weather protection in cold climates may not be sufficient for an indoor unit. 

On the off-chance, if you’d remotely like to consider a storage tank water heater, we’ve reviewed the following models and can vouch for their consistent and satisfactory performance over the course of decades. 

Bradford White Water Heaters Review
Rheem Fury 22V40F1 40 Gallon Water Heater Review 

3. Advanced Feature Sets

Modern tankless water heaters offer advanced features such as WiFi connectivity and monitoring, remote control, frost prevention, multi-fuel capability (natural gas or propane), corrosion-resistant construction, and other useful features. Some features are standard, while others are add-on components.

While many of these features can prove useful, they do sometimes increase purchase costs. If there is a cost increase, be sure to weigh the usefulness that feature serves for your household against the added cost.

4. Warranty

The best tankless gas water heater models usually come with various warranties for different components. A standard warranty for heat exchangers is 10 to 12 years, five years for certain parts, and often one year for labor.

Top Tankless Gas Water Heater Brands

It’s hard to say which is the best water heater brand, but there are certainly a few that stand out from the crowd.

1. Rheem

Rheem tankless gas water heaters provide years of reliable, energy-efficient, high-capacity service for your home. They are the top-rated tankless water heater for performance and value and often receive positive ratings in tankless gas water heater reviews.

2. Rinnai

Rinnai is a long-standing tankless water heater company with products in use for nearly a century. Their units are high efficiency, low emission, and often have a high flow rate. Most of their water heaters come with a 12-year warranty as well, which is at the high-end of the industry average. It’s no wonder more than one of their products rank among the best on-demand gas water heaters.

3. Takagi

Takagi tankless gas water heaters have one of the highest flow rates of all the brands (10 GPM). Their condensing units operate quietly and are energy efficient.

4. Noritz

Noritz high-efficiency tankless gas water heaters are ideal for smaller homes or apartments. They are high-altitude and propane compatible, making them good candidates for smaller mountain homes.

Wrapping It Up

Your choices for a gas tankless water heater may seem a little overwhelming, even after reading our tankless gas water heater reviews. However, if you take the size of your home, the number of fixtures, and the number of people or family members living there into account, you can pretty quickly decide which of these tankless gas water heaters is the best tankless gas water heater for your house.

Cost is always a consideration, so review your family finances and the potential savings impact a new tankless gas water heater could have on your energy and water bills. Self-installation is an option for most of the water heaters recommended, especially if you’re mechanically inclined, but don’t hesitate to call a professional if you’re unsure about working with gas and water lines. Older homes may find the cost of a tankless gas water heater includes retrofitting old gas and water lines, too.

Finally, think about your home’s future. Is your family growing? Is your existing storage-tank water heater rapidly approaching its end of life? Are you going to list your house for sale in the near future and want to maximize your resale value? These questions and others can help you decide which is the best tankless gas water heater for your budget and your family.

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