7 Best Tankless Gas Water Heater That Provide Fast Results

best tankless gas water heater

Are you looking for an energy-efficient & cost-effective water heating solution? Look no further than a tankless gas water heater. Tankless gas water heaters are an excellent choice for those looking for a reliable way to heat their water. Unlike traditional tank-style water heaters, the best tankless gas water heater provides an endless hot water supply. They are also much more compact, making them ideal for those with limited space. 

Additionally, tankless gas water heaters can save you money in the long run, as they are more energy efficient and require less maintenance. With so many benefits, it’s no wonder why tankless gas water heaters are quickly becoming the go-to option for homeowners and businesses alike. 

To help you find the best tankless gas water heater for your needs, I’ve put together this comprehensive review of the top models on the market.

Comparison Of Best Tankless Gas Water Heater






Rinnai V65iP Propane Tankless Hot Water Heater

Natural gas power source, 6.6 gallons capacity, Enhanced scale detection


4.5 / 5 

Eccotemp i12-NG Tankless Gas Water Heater

Features fully automatic temperature controls, Natural gas power source, 4.8 gallons capacity


4.2 / 5 

Rinnai RU199iN Sensei High-Efficiency Water Heater

Energy and space efficient, Natural gas power source, Optimal water pressure


4.5 / 5 

Noritz NR66ODNG Outdoor Tankless Gas Water Heater

Ideal for outdoor applications, Natural gas power source, 6.5 gallons capacity


4.2 / 5 

Rinnai RL75iN Water Heater, 7.5 GPM

Never run out of hot water, Smart and durable design, Natural gas power source


4.4 / 5 

Takagi T-H3-DV-N Condensing High-Efficiency Natural Gas Indoor Tankless Gas Water Heater

Endless hot water, 10 gallons capacity, Natural gas power source


4.0 / 5 

Camplux 5L 1.32 GPM Outdoor Water Heater

Instant hot water, 3.0 PSI water pressure startup, 1.32 gallons capacity


4.4 / 5 

How I Chose The Best Tankless Gas Water Heater

The most reliable tankless gas water heaters are power-conserving and strong enough to supply a sufficient amount of hot water for an entire family.

The items on my list have been chosen for their dependability, energy efficiency, and fluid flow rate, surpassing those of their rivals.

The top list has various dependable models with outstanding flow rates and fuel usage. My top selections include some extra technology to assist consumers in cutting their energy expenses while still furnishing sufficient hot water.

In my study, I examined the power input and exhaust systems such as direct-vent and power-vent (condensing and non-condensing units) to create a list of my best suggestions applicable to various family sizes.

Things To Consider Before You Buy The Best Tankless Gas Water Heater

To help you find the best tankless gas water heater for your needs, I’ve put together this comprehensive review of the top models on the market.

Here are the things to consider while selecting the best tankless gas water heater: 

Propane Vs. Natural Gas

Homeowners can usually take advantage of a tankless water heater that runs on natural gas as it is supplied straight to the residence by the local gas utility. Generally, natural gas is less expensive than propane. However, the pricing may differ depending on the area and local expenses.

People who reside in rural areas, campers, and those not connected to a power grid are usually limited to propane as a fuel source. Therefore, consider purchasing the best tankless gas water heater compatible with propane if this applies to you.

It is fortunate that many companies that make water heaters sell kits that let people switch their natural gas water heater to a propane heater and also switch a propane heater to a natural gas one.

Indoor Vs. Outdoor Application

An outdoor tankless water heater is not recommended in areas where winter temperatures fall below freezing because it will not work as efficiently and could get frozen and harmed. That’s why most homeowners opt for an indoor tankless water heater.

In some instances, it may be good to have an outdoor water heater, such as for a pool house or far away from civilization (e.g., while camping).

An exception to the rule occurs when an interior tank-style electric water heater is replaced with a tankless gas heater, but the house does not have a gas line or does not have a suitable way for venting installation. This would not be a problem if the house already had a gas water heater.

If an individual desires a gas tankless water heater for an outdoor setting, it is necessary to insulate and safeguard it, possibly in an attached garage or shed, to reduce the destruction chances and energy waste by cold weather.

Flow Rate (GPM)

It is essential to accurately measure the size of the tankless water heater during selection. This will ensure you have enough hot water to meet all your requirements.

When evaluating tankless water heaters, GPM (gallons of hot water per minute) is the key measurement. To decide how much GPM your home requires, consider how much hot water each of the following fixtures and appliances utilizes on average.

  • Shower – 2.5 GPM
  • Clothes washer – 1.5 GPM
  • Bathroom or kitchen faucet – 0.5 GPM
  • Dishwasher – 1.0 GPM

For instance, if two people in a household take a shower while the dishwasher is still in operation. Then, your tankless water heater should be able to give out a minimum of 6.0 gallons per minute.

If you are uncertain, select a water heater with a flow rate of 0.5 to 1.0 GPM higher than the expected maximum during peak periods of hot water usage.

Power Input (BTU)

A tankless water heater’s performance in heating water is linked to its BTU input, which is an abbreviation for “British thermal unit.” One single BTU is the energy required to raise one pound of water by a single degree Fahrenheit.

When you are in the market for a tankless gas water heater, look into its highest BTU-per-hour input rating.

You can calculate an appropriate BTU rate for a gas tankless water heater using sophisticated mathematical equations dependent on climate and whether the model is condensing or non-condensing.

You can rapidly determine the accurate BTU input using a sizing calculator available online (such as the one offered by Rinnai, a leading producer of tankless water heaters).

As an easy guideline:

  • A home with 2 bathrooms and 2-3 adult or teen family members will require 190,000 BTUs.
  • On average, a family of 1-2 adults or teens in a home with just 1 bathroom will require 140,000 BTUs.
  • A home with 3 bathrooms and 3-5 adult or teen family members will require 380,000 BTUs.

Please Note: Compared to adults and teenagers, who utilize hot water for washing dishes, laundering clothes, and taking hot showers, young children tend not to consume as much of it. Therefore, one or two kids in each group would not cause any significant variation in the size of the appliance. However, bump up to the next size if the family has 3 or more young children.


Both propane & natural gas tankless water heaters generate a hot exhaust that needs to be vented outside of the house in an appropriate manner. It is not mandatory to vent outside units, whereas inside units need ventilation using one of the two available means.

  • Direct-vent – This ventilation style necessitates two tubes; one takes in air from outside, and the second pipe discharges the exhaust fumes through a different pipe to the outside, either through an outer wall or the roof.
  • Power-vent – In this kind of venting system, the air is taken in from the house’s interior and then expelled outside using a fan, generally out of an exterior wall.

Gas-fired tankless water heaters can be either direct-vent models or power-vent models, so you should select the one that matches the existing venting set up in your home.

An accredited plumber must install a tankless gas water heater, have a professional plumber inspect the venting system, and identify the most appropriate tankless water heater for your needs.

Condensing Vs. Non-condensing

As power prices keep increasing, manufacturers are constantly creating methods to make appliances more environmentally friendly.

Presently, most tankless gas water heaters available are non-condensing. Each type of heater has its advantages and disadvantages.

  • Condensing – The newest tankless gas water heaters have an additional heat exchanger that uses recirculated exhaust gases to further heat the water. The repeating heat cycle amplifies the unit’s performance to nearly 90%.

When the fumes come out from the outlet, they cool down by 100 degrees Fahrenheit. Investing in a condensing unit will help you save energy in the long run, although it will cost more initially (around $1,200 to $2,000, not including installation fees).

  • Non-condensing – This gas-powered tankless water heater can be an excellent choice for replacing an existing tank-style gas water heater because it connects to the same exhaust vent as the old unit. A non-condensing unit comes with a single heat exchanger. When the fumes come out, they are warm (as high as 300°F). This causes the depletion of thermal energy.

A non-condensing unit tends to be more affordable upfront, with prices ranging from around $600 to $1,200, excluding the installation fee. This type of unit typically has an efficiency rating of 80 percent.

Best Tankless Gas Water Heater

1. Rinnai V65iP Propane Tankless Hot Water Heater


  • Natural gas power source
  • 6.6 gallons capacity
  • Enhanced scale detection
  • Smart and durable Design
  • Professional installation



+ Works great in a small cabin
+ Great product for the price
+ Amazing tankless water heater
+ Fairly simple installation
+ Excellent replacement
+ Great features
+ Very good unit
– No helpful tech support

This Rinnai tankless water heater is crafted to work with a maximum efficiency of 82 percent and can be placed outside. It will certainly not fail to satisfy.

This product offers a maximum input of 150,000 BTU and can produce up to 6.5 GPM of hot water, making it an excellent choice for households with one or two bathrooms and one to two occupants.

This Rinnai model can connect with your wireless internet connection and mobile devices. You can also purchase a digital controller to use with it (as a separate item).

Reviews from customers


Patrick S, a resident of the United States, considered Rinnai V65iP a fantastic tankless water heater. He said, “Hot water is consistent. I was able to reuse the vent system. The unit is much quieter than the one I had before. The heater is easy to install. It works great in a small cabin.”

Tyler’s Projects considered Rinnai V65iP as his favorite appliance in his entire house. He said, “This changed how all our showers work for the better. I have full cold water pressure at the same time as full hot water. This leads to a very high pressure, very satisfyingly steamy shower.”

Further, he added that “I can wash my car with steaming hot (140 dgF) water @ 60 PSI easily. The unit never chokes or gets cold. I can run a dual-head shower while running the dishwasher. You can run a trickle of hot water with this unit. My last unit would only kick on if you had the hot water turned at least to half-strength. This one has very fine controls, operating flawlessly at around .5 GPM.”

2. Eccotemp i12-NG Tankless Gas Water Heater


  • Features fully automatic temperature controls
  • Natural gas power source
  • 4.8 gallons capacity
  • Easy to use LED display controls
  • Safe electronic ignition system
  • Sleek and modern design



+ Energy efficient endless hot water
+ Perfect for hunting camp
+ Good value for money
+ Beautiful design
+ Easy to install
+ Affordable
– Inconsistent

This high-quality tankless water heater can supply a flow rate of up to 3 GPM, making it suitable for simultaneously utilizing both a shower and a tap.

When the flow rate is 3 GPM, the temperature increase is 35-40°, and when it is 1.5 GPM, the temperature increase is 77°. Furthermore, it comes with a UL-certified child-lock mechanism that prevents accidental usage.

One of the primary advantages of this tankless gas water heater is its compact size. It is relatively small, measuring only 16″ x 16″ x 11″ and weighing only 33 lbs, thus taking up minimal space on a countertop or wall. Additional points are its LED display, which reveals valuable facts like the temperature and flow rate (gallons per minute).

If you’re searching for the best water heater for your residence, then the Rinnai RUC98iN Ultra Series Indoor Natural Gas Tankless Water Heater is an excellent choice. According to customers’ feedback, this terrific item includes both Concentric and PVC ventilation alternatives that deliver an energy factor as high as 0.96 and are reportedly effortless to install.

Generally, purchasing a gas-powered vehicle is typically more costly than buying an eco-friendly electric model. If you’re looking to cut costs, a gas model might be the better option as it’s cheaper to run than an electric one with a digital screen and remote control.

Reviews from customers


Gale Laidlaw considered Eccotemp i12-NG perfect for campers. He said, “I purchased this heater to install in my camper. It was easy to set up. I like that it shows what temperature the water is at and your GPM when running hot water. Overall it feels like a solid unit. Easy to read and use display.”

Arlando gave Eccotemp i12-NG 5 stars due to its efficiency, looks, performance, and ease of start-up. He said, “This unit works great with more than enough hot water. The space I installed it in is approx. 800 sq ft one bedroom with kitchen, bathroom, and laundry room. I suggest you use quality Teflon tape and tighten the fittings well.”

3. Rinnai RU199iN Sensei High-Efficiency Water Heater


  • Energy and space efficient
  • Natural gas power source
  • Optimal water pressure
  • 11 GPM hot water flow rate
  • Equipped with Circ-Logic
  • Endless hot water
  • 11 gallons capacity



+ Excellent performance in an alpine climate
+ A good whole-house water heater
+ Straightforward and easy install
+ Never run out of hot water
+ Great instant hot water
+ High quality product
+ Quiet machine
– Expensive

Rinnai’s model offers impressive energy efficiency and is well-suited for the hot water needs of a typical family.

This super-efficient condensing unit captures and recycles hot exhaust gases, minimizing energy loss and reducing utility bills.

This heater has a substantial hot water flow of 11 GPM, plus a maximum BTU input of 199,000. You don’t have to sacrifice doing a laundry load or enjoying a lengthy hot shower.

Rinnai utilizes ThermaCirc360 technology which circulates heated water through the house’s plumbing to ensure that one does not have to endure irritating pauses after turning on the tap to get hot water.

The Rinnai comes with WiFi monitoring, enabling it to schedule pre-circulation times (like when you rise in the morning) and provide the capability to examine the unit’s performance from your tablet or cell phone.

Reviews from customers


Dante was impressed with Rinnai RU199iN. He said, “This heater offers endless hot water. It has an easier installation than expected. Just take care of proper gas requirements recommendations regarding the pipe sizing and the exhaust. The product works great and saves a lot of space.”

Gordon G considers Rinnai RU199iN as a great product with great support. He said, “The unit itself is very quiet. I can only hear it when standing next to it. The fan that runs the exhaust air is also far quieter than the fan on the old tank heater.”

He added, “If you have a tub and use it, a tankless heater is a must-have because you will have unlimited hot water to fill it and keep it warmed up.”

4. Noritz NR66ODNG Outdoor Tankless Gas Water Heater


  • Ideal for outdoor applications
  • Natural gas power source
  • 6.5 gallons capacity
  • Endless hot water
  • High efficiency



+ Nice water heater
+ Awesome unit
+ Great price
+ Durable
– Minor issues

This gas water heater is well suited to large households of up to five people in three bedrooms due to its 6.5 flow rate. Additionally, it is lightweight at only 33 pounds.

What I like about this tankless gas water heater is that it can be utilized with either natural gas or liquid propane, making it convenient to transport anywhere without being attached to a gas line.

Individuals who often travel or move from one home to another would find it beneficial to purchase a tankless water heater as it would help them save installation costs. Furthermore, having this type of water heater would significantly enhance their comfort level.

All models in the Noritz EZ series provide an unlimited hot water supply, the installation process is simplified, and the space requirement is reduced compared to tank units.

Reviews from customers


Brandon considers the Noritz NR66ODNG an excellent unit. He said, “I installed it in summer and loved it. It takes a little longer to get hot water, but when it hits, it never stops. I had to use heat tape on the pipes and insulate them. I have used both showers simultaneously, and the heater handled them easily.”

WSC RN said that “I upgraded from an older, smaller capacity unit. This is very compact and works nicely for my 3 BD, 2 BA, and 5-member household. The water heater works fine. The installation went smoothly.”

5. Rinnai RL75iN Water Heater, 7.5 GPM


  • Circ-Logic technology offers recirculation patterns
  • Never run out of hot water
  • Smart and durable design
  • Natural gas power source
  • Professional installation
  • 7.5 gallons capacity
  • Original design



+ Consistent and efficient water
+ Great investment
+ Endless hot water
+ Excellent heater
+ Worth the money
– Too expensive to install

This Rinnai model is ideal for households with two bathrooms and two to three inhabitants. It offers up to 7.5 gallons per minute of hot water flow and has a maximum output of 180,000 British thermal units to reduce utility bills.

This tankless water heater powered by natural gas does not need to be condensed. It uses Rinnai’s ThermaCirc360 technology to ensure that hot water is available immediately when the tap opens.

This device can connect to WiFi and be operated and configured from a distance.

Reviews from customers


Spaceman highly recommended the Rinnai RL75iN water heater. He said, “Not much space in my mechanical room, but this heater is awesome! It keeps my bills down low and my water temperature hot! No problem running multiple sinks or showers simultaneously. Keeps up with the demand.”

CJ said that “This heater is extremely reliable. I can easily run two showers at once and have laundry and dishwasher running simultaneously. This heater can pump out a tremendous amount of hot water. It does require some plumbing skills, but all in all, it wasn’t bad. I think the placement of the unit is really important and should be as close as possible to your venting location.”

6. Takagi T-H3-DV-N Condensing High-Efficiency Natural Gas Indoor Tankless Gas Water Heater


  • Endless hot water
  • 10 gallons capacity
  • Natural gas power source
  • Computerized safety features
  • Primary heat exchanger
  • Space saving
  • Compact



+ Great tankless hot water heater
+ Amazing product
+ Easy to install
+ Durable
– Minor issues

This gas-powered tankless water heater can heat the water by 35°F with a 10 GPM flow rate or by 70°F with a flow rate of 5.4 GPM. It is beneficial that less water is required to achieve higher temperatures.

A 5.4 gallons per minute flow rate is ample for washing large dishes and other laborious commercial operations.

This tankless gas water heater has been approved by the National Sanitation Foundation (NSF) for meeting the food safety and hygiene criteria.

This feature is a tremendous advantage for restaurants responsible for managing food service equipment. It is noteworthy that this is the only tankless gas water heater to be given an Energy Star rating.

Reviews from customers


Wordwrkr loved the Takagi T-H3-DV-N water heater. He said, “I installed this unit a couple of weeks ago, and it’s been working like a charm. It was pretty easy to install. The higher the temperature set point, the less throughput because it takes longer to get the water up to temperature.”

SodaBrew said, “Takagi water heaters are very well made, and installation is straightforward. These new high-efficiency condensing heaters do not require stainless steel exhaust vents; PVC is fine. They get all the heat out of the gas burner and leave very little in the exhaust air.”

7. Camplux 5L 1.32 GPM Outdoor Water Heater


  • Instant hot water
  • 3.0 PSI water pressure startup
  • 1.32 gallons capacity
  • Battery-powered power source
  • Lightweight, portable design
  • Portable



+ Outdoor shower with tankless water heater
+ Excellent customer service
+ Hot water on demand
+ Great for camping
+ Easy to use
– Not durable

Camplux portable tankless water heater lets you enjoy hot water wherever you go, even if camping or off the grid This propane-powered water heater provides up to 1.32 GPM, supplying enough hot water for shower or washing dishes.

Camplux water heater won’t heat enough water to run a household at 28,000 BTU per hour. But, it will be a welcome addition where no other source of hot water is found.

The igniter on this heater needs 2 D-cell batteries (or you can plug it into a standard outlet). 

The Camplux water heater can be connected to a 12V water pump to amplify the pressure, plus it includes a handle that can be suspended from a hook or a sturdy tree branch.

Reviews from customers


Clay H. Padginton considered Camplux 5L great for camps. He said, “When initially installed, I couldn’t get it to stay lit, but once the water pressure was high enough, it worked great. I would give it a 5, but some of the fittings are cheap plastic, and I expect it will wear out rapidly and start to leak.”

Dale T. is delighted with the purchase of Camplux 5L. He said, “This heater is smaller, lighter, and works better than my old one. It felt so good to shower and not have to turn the water off so it could cool down. In addition, it works great on my 5th wheel, and I am very happy with it.”

Reasons To Buy The Best Tankless Gas Water Heater

Here are the reasons to buy the best tankless gas water heater: 

Environmentally friendly

Tankless water heaters only utilize energy to heat water, making them more efficient and less of a burden on the environment. On the other hand, tank water heaters must keep a tank full of warm water whether on usage or not. Tankless water heaters powered by electricity from renewable sources are particularly advantageous for the environment.

Space saving

You can increase the potential storage or living space by removing a tank-style water heater and replacing it with a tankless version. No matter the size of your new tankless water heater, it’ll definitely be smaller than the tank heater it replaces.


Endless hot water is the most popular reason to choose a tankless water heater. Traditional tank water heaters can only supply hot water until they run out of it. If you have a tank water heater, you’ll have to wait for a full tank to warm up. Tankless water heaters can offer hot water on demand and in as much quantity as you need.

Long lifespan

Traditional water heaters need replacement after 8 to 12 years of use. On the other hand, tankless water heaters that are maintained regularly can last up to 2 decades. Tankless water heaters last longer, but most of their parts are replaceable, unlike tank water heaters with only a small number of repairable parts.

FAQs (Frequently Asked Questions) On Best Tankless Gas Water Heater

1. What is the disadvantage of tankless water heater?

The capacity of a tankless water heater is limited in terms of how much water it can heat simultaneously. If you need a greater quantity of hot water, for example, if you are running the dishwasher, washer, and shower concurrently, then the water temperature will differ. This is because the heater attempts to provide hot water for all three places simultaneously.

2. Which is better gas water heater or tankless water heater?

The operation of storage tank water heaters is more straightforward than tankless types, leading to cheap upkeep and fixes. The straightforward design of tank-style water heaters facilitates simple, inexpensive repairs when they malfunction. Conversely, repairing or replacing tankless water heaters is more complex and costly.

3. What is the most common problems with tankless water heaters?

Here are 6 most common problems with tankless water heaters:

  • System overload
  • Air supply or exhaust blockage
  • Flame failure
  • Mineral buildup
  • Cold water sandwich
  • Ignition failure.

4. What is the lifespan of a tankless water heater?

The tankless water heater lifespan is 20 years, with proper upkeep. Models with a copper tankless heat exchanger are typically under warranty for 12-15 years.

Conclusion: Best Tankless Gas Water Heater

Tankless water heaters are an excellent way to save money on utility bills & save the environment. They provide endless hot water on demand. In addition, they are the least expensive and most efficient way to provide hot water in your home.

The best tankless water heaters have a flow rate of at least 5 gallons per minute. Higher flow rates are better because they result in a more consistent flow of hot water throughout the day and night.

In addition to providing endless hot water and high-quality heating, the best tankless gas water heater also comes with high-tech features that save energy and money. 

These features can include low-flow and variable-flow features that reduce the amount of hot water used during specific periods of the day or year, weather sensors that prevent water from being heated unnecessarily, and an energy monitor that saves money.

I hope this article on the best tankless gas water heater sounds helpful!

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