Best Tankless Gas Water Heater

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Tankless gas water heaters are increasing in popularity among many American homeowners. Unlike their counterparts (electric and tank-based), they are relatively economical in the long haul. Some will even require hassle-free maintenance with self-diagnostic codes for troubleshooting.

That means they last long enough to give you an endless supply of hot water, as long as you need it. Tankless water heaters come in compact hardware designs and shapes. You don’t need to overhaul your house arrangement or drill extensive plumbing halls to install a high-quality model.

We tested and reviewed seven products to bring you the best options that reflect your investment’s value. We also leverage expert reviews, direct recommendations, and buyer feedback to shortlist the most popular, high-quality products. Our nerve-wracking expedition found Rinnai Indoor Tankless Hot Water Heater to be the best product overall and Noritz NRC66DVNG Indoor Condensing Direct Tankless Hot Water Heater as the best runner-up.

You can buy the best product in our review list if you want an intuitive technology that enhances performance and energy efficiency. The best runner-up product is ideal if you want a high-quality water heater built for longevity and durability. Other products in this buying guide include the best budget, the best for residential applications, the best portable, the best energy-efficient, and the best condensing tankless water heater.

Best Tankless Gas Water Heaters

  1. Rinnai Indoor Tankless Hot Water Heater– Best Overall
  2. Noritz NRC66DVNG Indoor Condensing Direct Tankless Hot Water Heater– Best Runner-Up
  3. Eccotemp i12LP Water Heater– Best Budget
  4. Rinnai RUR199iN Tankless Gas Water Heater– Best Residential
  5. Hike Crew Portable Propane Water Heater and Shower Pump– Best Portable
  6. Rheem RTGH-95 DVLN Indoor Direct Vent Tankless Water Heater– Best Energy Efficient
  7. Takagi T-H3-DV-N- Condensing High-Efficiency Natural Gas Indoor Tankless Water Heater– Best Condensing Tankless Water Heater

Best Tankless Gas Water Heater Reviews

1. Rinnai Indoor Tankless Hot Water Heater

Rinnai Indoor Tankless Hot Water Heater is the best overall product on our list, thanks to its intuitive technology that enhances performance. For instance, you can choose the optional control smart Wi-Fi to adjust the temperature settings using voice command or remote access. That means you can have control of your entire system from the comfort of your living room.

This product ensures that you never run out of hot water regardless of how often you need it. It has recirculation capabilities, powered by ThermaCirc360, which can save up to 11,000 gallons per year. This technology is compatible with an external pump, especially if you often experience high-demand applications. Even so, you’ll have to purchase the external pump separately.

Rinnai Best Tankless Gas Water Heater

The Rinnai model is ideal for any homeowner who maximizes space and wants to conserve energy. This model is compact and will quickly fit in a wall unit to freeze up more usable areas in your living space. It features a Uniform Energy Factor (UEF) rating for high energy efficiency to save you from unreasonably expensive costs.


  • Warranty – Limited warranty
  • Energy Star Rating – ENERGY STAR rated
  • Suitable for What House Size? – Four appliances
  • Water Temperature – 98-140°F
  • Flow Rate – 7.5 GPM
  • Gas Type – Natural gas
  • Installation Type – Indoor use only

2. Noritz Indoor Condensing Tankless Gas Water Heater

Noritz NRC66DVNG made it to our review list as the best runner-up, thanks to its high-quality design and longevity. The manufacturer gives a 12-year limited warranty on heat exchangers and a 5-year limited warranty on parts. Thus, this water heater makes a go-to product if you want a 100% customer satisfaction guarantee. Most importantly, you also get a one-year warranty on labor for service and repairs.

This product comes with a remote thermostat and a 6-inch power cord. You don’t have to purchase these items separately, hence saves your budget for the initial cost. We installed it in about half an hour without hiring professional plumbing skills. The technical support team is also reliable and will return your calls if you experience any difficulties during installation or maintenance.

Noritz Best Tankless Gas Water Heater

Besides high efficiency and steady flow rates of up to 6.6 GPM at 140°C temperature rise, it has low NOx emissions for a greener home. You can vent this product on 40/80 PVC, PP, or CPVC plumbing fixtures. You can also buy other accompaniments (sold separately) to improve efficiency during on-demand applications. They include an atmospheric conversion kit and horizontal termination PVT-HL.


  • Warranty – 12-year heat exchanger warranty
  • Energy Star Rating – ENERGY STAR rated
  • Suitable for What House Size?
  • Water Temperature – 120, 135, or 140°C
  • Flow Rate – 6.6 GPM
  • Gas Type – Natural gas
  • Installation Type – Indoor use only

3. Eccotemp Tankless Gas Water Heater

Eccotemp i12Lp Water Heater makes the best budget product if you want instant hot water without breaking the bank. It is ideal for small households of about four people.

We love the child locking technology in this model that makes it suitable for young families with young children. Thus, you’ll never worry about your kid activating the highest temperature setting if you aren’t around.

This product is multifunctional, thanks to its high portability. You can carry it to vacations, cottages, or small holiday homes. It is relatively easy to install, and you don’t need to bring your plumbing toolbox every time you travel. It comes with a ready-to-install stainless steel vent kit and a UL-listed power cord. A quick look into the installation guide will get you going.

Eccotemp Best Tankless Gas Water Heater

Eccotemp water heater is also ideal if you’re after aesthetic appeal. The seek black-tempered glass blends into any living space to complement your interior décor. It comes with a bright LED display for easy operations. The controls accessible via the LED display include GPM measure and desired temperature.


  • Warranty – Two-year limited manufacturer warranty
  • Energy Star Rating – ENERGY STAR rated
  • Suitable for What House Size? – Three family members
  • Water Temperature – 77° F
  • Flow Rate – 4 GPM
  • Gas Type – Liquid Propane
  • Installation Type – Indoor use (wall mount)

4. Rinnai Tankless Gas Water Heater

Rinnai RUR199iN Tankless Gas Water Heater allows you to connect up to six appliances with high flow rates of up to 11GPM. You’re looking at the best residential product with ultra-low NOx emissions for eco-friendliness. Even though it comes at a relatively higher price tag than other models in this review list, it reflects your money’s value.

Like other Rinnai water heaters, this product comes with Wi-Fi-enabled control features to enhance your experience through voice command.

You can also opt for remote access controls if you don’t want to touch the system every time you wish to adjust the temperature settings. This model makes the only product in our list available in both natural gas and liquid propane option.

Rinnai Tankless Gas Water Heater

This water heater is energy efficient as it goes into idle mode when not in use. The heat exchangers will only power on if you need hot water. Besides saving energy costs, this feature ensures that the system’s components outshine their lifespan by preventing overheating. It is ideal for multiple uses, including showering, laundry, and dishes.


  • Warranty – 120 months residential factory warranty
  • Energy Star Rating – ENERGY STAR rated
  • Suitable for What House Size? – Six appliances
  • Water Temperature – 98-140°F
  • Flow Rate – 11 GPM
  • Gas Type – Natural gas & Liquid Propane
  • Installation Type – Wall-mounted

5. Hike Crew Portable Tankless Gas Water Heater

Camping and hiking can be a daunting hobby, especially when you choose to visit cold climate regions. Hike Crew Portable Propane Water Heater and Shower Pump will ensure that you never miss your outdoor showers again because of cold.

It comes with a storage case for the system, shower head, and other accessories for easy transportation. It is relatively lightweight, and you can carry it to hilltops.

This heater comes with a water flow sensor that extinguishes the burner if the water supply dries. Thus, it is safe for use and also conserves energy. The pump power connector is long enough to deliver showering water from an external bucket/reservoir at a safe distance.

Hike Crew Portable Tankless Water Heater

The faucet control allows you to adjust the desired flow rates. The temperature increase is proportionate to the flow rate. Thus, higher flow rates mean a higher temperature.

How do you connect this water heater to a power source at the camping site? It comes with an AC adaptor that plugs into a standard generator. The RV outlet can also suffice for this function. Similarly, use the 12 DC power adapter to plug into your car cigarette lighter. It works well with any car model.


  • Warranty – Limited warranty
  • Energy Star Rating – None
  • Suitable for What House Size? – Two users
  • Water Temperature – 125° F
  • Flow Rate – 0.6 GPM
  • Gas Type – Liquid propane
  • Installation Type – Outdoor use

6. Rheem Indoor Tankless Gas Water Heater

Rheem RTGH-95 DVLN makes a go-to product if you want an indoor tankless water heater that saves energy costs while giving you an uninterrupted supply of hot water.

This product satisfies GAMA third-party energy efficiency listing. It also features a 94% energy-efficient stainless steel condensing heat exchanger and intelligent control settings that also enhance energy efficiency. Briefly, you’re looking at a product that will significantly cut down your monthly and annual energy costs.

You can buy this product if you live in an apartment as it has high altitude compliance of up to 9,840 feet above sea level. The installation process is pretty simple, and you can do it in less than an hour, as we did. It has a compact size to fit in small spaces such as a medicine-sized wall cabinet.

Rheem Indoor Tankless Gas Water Heater

Rheem water heaters are pretty forthcoming in innovative technology, and this product isn’t an exception. For instance, it has a hot start programming to minimize water temperature fluctuations. You’ll spend your mornings preparing for the day instead of waiting by the heater for the water to reach desired temperatures.


  • Warranty – 12 years limited warranty
  • Energy Star Rating – ENERGY STAR rated
  • Suitable for What House Size? – Three bathrooms
  • Water Temperature – 45°C
  • Flow Rate – 9.5 GPM
  • Gas Type – Natural gas
  • Installation Type – Indoor application

7. Takagi Condensing Indoor Tankless Gas Water Heater

Lastly, you can opt for this Takagi T-H3-DV-H model if you’re looking for a condensing tankless water heater with high energy efficiency. This product allows you to enjoy endless hot water with on-demand usage throughout the year.

It is ideal for a household of four but will still function optimally with additional guests around, thanks to the steady flow rates of up to 10 GPM.

Say goodbye to water heaters that jeopardize the safety of users and your pets. This model comes with automatic safety features. For instance, we found the freeze, overheat, and surge protection to be helpful if you’re not around to monitor the system physically. You can also run the diagnostic codes for troubleshooting if you notice a decline in performance.

Takagi Indoor Tankless Gas Water Heater

We also love the Ultra Low NOx Emissions that promote a greener living space. This model satisfies the 2012 SCAQMD Rule 1146.2 for eco-friendly products. The manufacturer also installed commercial-grade copper alloy primary heat exchangers built for longevity and high performance.


  • Warranty – Limited warranty
  • Energy Star Rating – ENERGY STAR rated
  • Suitable for What House Size? – Four family members
  • Water Temperature – 100-185 °C
  • Flow Rate – 10 GPM
  • Gas Type – Natural gas
  • Installation Type – Indoor use only

Buying Guide for Tankless Gas Water Heaters

Things to Consider before purchasing a Tankless Gas Water Heater

Water Type

What’s your water source? Is it a municipal city water supply or a private well? While nearly all heating systems can heat hard and soft water, getting a water heater dedicated to your type of water sounds like a good plan. Check the product description beneath every model to determine whether it’s for pipe or underground water.

Technical Assistance

Any water heating system can malfunction, whether it’s a generic or OEM model. Even though the chances are low if you invest in a high-quality product, you still need unrestricted access to the manufacturer’s technical assistance team because you don’t know when you would need them. That means a reliable customer care team that returns your calls and to online inquiries.

Factors to Consider before buying the Best Tankless Gas Water Heater

Even with a trusted direct recommendation from an expert, it can still be challenging to choose the best tankless gas water heaters, especially with overwhelming options. Every homeowner has different aesthetic preferences and water heater applications. Thus, a system that functions optimally for your neighbor’s household may not work the same way in yours. Consider these factors to choose a model that reflects your budget and needs:

Size/ Capacity

Size or capacity refers to the number of users or water fixtures that the system can support without overloading to reduce its flow rate and efficiency. A high-capacity water heater can serve big households of up to eight family members or showerheads.

You’ll also need a high-capacity water filter if you have multiple applications such as laundry and dishes. Alternatively, a low-capacity water heater is ideal for small households of about one or two people.

Hardware size will vary with every model. Some water heaters are compact enough to fit in a wall cabinet, while others require wall mounting. If you opt for the latter model, choose a brand that comes with a mounting bracket and screws at zero additional costs.

Energy Efficiency/ Energy Star Rating

Enjoying an unlimited supply of hot water across all the showerheads in your house doesn’t mean that you should incur unreasonably high energy costs. The most prevalent energy efficiency certification to watch out for is the ENERGY STAR rating, which features on all the products in our review list.

You could also watch out for models that come with intelligent technology, such as the auto power on and off feature to save energy when the system is idle. Some superior brands will even come with a dedicated vacation mode that saves energy during holidays when you’re not around. Other energy-saving features include commercial-grade copper heat exchangers.


No product comes at the “best” price. In most cases, pricing is relative and depends on several factors. For instance, the higher the quality of a product, the higher its price will likely be. Even so, not everything expensive is of high quality. Check all the features and specifications to see if they correspond to the price tag. In other words, a high price should reflect the system’s performance and durability.


Don’t spend on a water heater system that doesn’t come with clear warranty information. Warranty cushions you from the quality defects of a product that can affect its performance and longevity. Quality issues may emanate from the manufacturing or supply lines.

Most manufacturers give a standard one-year limited warranty on labor and parts. However, you can get high-quality models that come with a 12-year limited warranty and a separate five-year warranty on profit-free parts.

Flow Rate (GPM)

The flow rate determines the number of users at a time without experiencing delays. You would want a water heater with a steady flow rate across all the faucets. If you’re living in an apartment, going for a high-altitude compliant water heating system sounds like a good plan.

Also, note that some water heaters, especially outdoor models, regulate their water temperature settings with the flow rates. In other words, the water temperature rises with every flow rate increase. In that case, steady flow rates guarantee a high-temperature rise for instant hot water.


The venting compatibility affects application, efficiency, and the overall installation process. Go for a product that comes with additional venting accompaniments; otherwise, you’ll have to purchase them separately, at an additional cost. You’d also want a venting system that quickly attaches to your PVC pipes without additional plumbing tweaks.

A tight-fitting vent ensures zero leaking and that you enjoy steady flow rates without using more gas energy. Most models in our review list come with a direct vent that readily attaches to 40/80 PP and CPVC plumbing fixtures.

Condensing Vs. Non-Condensing

During the heating process, all water heaters release heat waste (sometimes excess depending on applications). This waste can corrode the system’s components. A condensing gas water heater recycles the excess heat and vent vapor that is no longer useful in the heating. Thus, you can use such a model in a standard venting system such as PVC without worrying about corrosiveness.

Moreover, these models give you up to 95% energy efficiency. On the other hand, a non-condensing tankless gas water heater will vent out all the by-products at higher temperatures of up to 150° C.

Thus, you’ll need to install a heat sans corrosion-resistant venting channel if you want to get the most out of your water heater. That translates to expensive installation costs and energy waste in the long haul. If you’re working on a low budget, a condensing tankless water heater model sounds like the best plan.

Installation Type

Lastly, you would want to consider the installation design before purchasing a tankless gas water heater. The installation design is purely aesthetic but will also depend on your needs and preferences. For instance, an outdoor installation design is ideal if you have no additional space to accommodate an extra home appliance.

The components should be resistant to harsh weather conditions such as rainfall and extreme temperatures for longevity. Alternatively, an indoor installation design is a go-to option if you want to control your system with remote access or in-built Wi-Fi technology. Either way, both models will still give you an endless supply of hot water.

Wrapping It Up

Instant hot water showers save you time and encourage regular baths across the household. Taking frequent showers is healthy for the skin, eyes, and even hair (including beards). All the tankless gas water heaters in this review are of high quality and will give you an endless supply of hot water during on-demand applications. Even so, each product is unique and will provide you with varying experiences.

Rinnai Indoor Tankless Hot Water Heater remains the best product overall in our list for efficiency and steady flow rates. You can upgrade it to cater to as many points of use as possible. You can buy any of these water heaters from Amazon.


How does a tankless water heater work?

Tankless water heaters deliver a nearly endless hot water supply by using an electric element to warm the water as it travels through the pipe to the unit. Traditional water heaters store hot water in the unit. Tankless water heaters do not, making it a more cost-effective solution. 

What size tankless water heater do I need?

There are three questions to think about when trying to decide what size tankless water heater you need.

  1. What is the size of the home? A smaller house with one to three occupants should look for water heaters with 3 to 5 GPM output. A larger home with four or more occupants should look for a water heater with 8 or 9 GPM output.
  2. How many occupants are in the home? Based on how many occupants are in the house, what does their day-to-day usage look like?
  3. What region is the home located in? Areas where the average temps are lower, will require an increased output to heat the water.

How much money can I save with a gas tankless water heater?

There are numerous benefits to tankless water heaters, one of which is saving money. The savings vary but depending on the model of your heater; you can save between 5%-69% off your water heating bill. Specific models may also help you save up to $300 on your taxes. Unlike traditional water heaters, tankless water heaters only heat the water when you are actively using it, so you will see savings – up to $200 per year, depending on the demand and model.

Do high altitudes affect my gas tankless water heater?

High altitudes prevent gas tankless water heaters from functioning correctly. They are not as effective in very high-altitude areas. A great rule to remember is that a gas tankless water heater at an altitude over 4000 ft high will lose 4% of its BTU for every 1,000 ft above this height. 

Will one gas tankless water heater be enough to heat my entire home?

Yes, most gas water heaters are powerful enough to heat your entire home. You will want to make sure you properly size your water heater to meet the hot water demand. 

The H2Home Lab team is dedicated to helping you find the best solutions to your specific water needs, as well as provide troubleshooting tips and guides for water filtration, heating, softening and plumbing. We hope you will find the info you need on our site from any one of our buying guides or subject matter articles.