Best Gas Tankless Water Heaters of 2021 | Buying Guide & Reviews

Best Gas Tankless Water Heater Review
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Recently, tankless water heaters are in great demand because of their capacity of providing hot water the same as traditional type water heaters despite the size of the suitcase. Not only this, they are more efficient and easy to maintain than the tank water heater.

We have reviewed the top 6 best natural gas tankless water heaters, also known as on-demand water heaters, and developed the interactive guide so you can make a better buying decision.

Best Gas Tankless Water Heater
Rinnai V65IN (Best Indoor Water Heater)
  • Installation: Indoor
  • Fuel Type: Natural Gas
  • Capacity: 6.5 GPM
  • Max BTU: 150,000
  • Weight: 45.6 pounds
  • Warranty: 10 years on heat exchanger, 5 years on parts, 1 year labor
Rinnai V75EN (Best Outdoor Water Heater)
  • Installation: Outdoor
  • Fuel Type: Natural Gas
  • Capacity: 7.5 GPM
  • Max BTU: 180,000
  • Weight: 47.4 pounds
  • Warranty: 10 years on heat exchanger, 5 years on parts, 1 year labor
Rinnai RU199iN (Most High-end Indoor Water Heater)
  • Installation: Indoor
  • Fuel Type: Natural Gas
  • Capacity: 11 GPM
  • Max BTU: 199,000
  • Weight: 64 pounds
  • Warranty: 10 years on heat exchanger, 5 years on parts, 1 year labor
Noritz NR50ODNG
  • Installation: Outdoor
  • Fuel Type: Natural Gas
  • Capacity: 5 GPM
  • Max BTU: 120,000
  • Weight: 33 pounds
  • Warranty: 12 years on heat exchanger, 5 years on parts, 1 year labor
Rheem RTG-84XLN-1
  • Installation: Indoor
  • Fuel Type: Natural Gas
  • Capacity: 8.4 GPM
  • Max BTU: 180,000
  • Weight: 57 pounds
  • Warranty: 10 years on heat exchanger, 5 years on parts, 1 year labor
Takagi T-H3M-DV-N
  • Installation: Indoor
  • Fuel Type: Natural Gas
  • Capacity: 6 GPM
  • Max BTU: 120,000
  • Weight: 49 pounds
  • Warranty: 15 years on heat exchanger, 5 years on parts for residential use

Best Gas Tankless Water Heater

1. Rinnai RU199iN 11 GPM Gas Tankless Water Heater

Rinnai RU199iN 11 GPM Gas Tankless Water Heater

Rinnai is the #1 brand in the U.S. and Canada. If you have been looking for a gas water heater in the market, then chances are you may have come across the name twice or thrice.

Rinnai Ru199iN works on natural gas, providing hot water to the whole house. The compact design, unlike the conventional heater, saves a lot of space. This model needs electricity to run.

ThermaCirc360 Technology (built-in recirculation pump) recirculates the hot water, so you don’t need to wait for 10-15 seconds. One thing I admired about this heater is it can provide up to 11 GPM, so even with multiple faucets, you don’t need to worry about the flow.

For other water heaters, you need to install an additional recirculation pump. You don’t need to spend extra bucks on a dedicated pump for the recirculation process as Rinnai tankless water heater has a built-in recirculation pump. This ensures hot water to showers, sinks, washing machines, dishwashers, etc.

There are several ways to adjust the timer through the screen attached to the tanker and motion sensor. It is wi-fi capable so, you can control it from your smartphone via the control-R 2.0 mobile app.

You are saving more energy because it has a 0.96 EF rating, and this saving increases as you spend less water and gas.

Every part of the tankless water heater is easily replaceable. The average life expectancy of the Rinnai water heater is 20 years. The product weighs 73 pounds. The product is pricier than its competitors, but with these features, it really stands out.

It comes with 120 months warranty on the heat exchanger, 12 months warranty on labor, and 60 months warranty on parts.

What we like
  • It comes with a 10 years warranty on the heat exchanger.
  • The parts of the tankless heat exchanger are easily replaceable.
  • You can operate the water heater through an LCD and mobile app.
  • It has an energy saving of 0.96EF rating.
What we don’t like
  • It is pricier than its competitors.

2. Rinnai V65IN Natural Gas Tankless Water Heater

Rinnai V65IN Natural Gas Tankless Water Heater

As a global leader, the Japanese manufacturer has sold water heaters in more than 13 countries for the last 100 years.

The Rinnai V65iN provides hot water up to 6.5 GPM, which means you can run 2 showers and a dishwasher at the same time. The heating temperature ranges from 98°F to 140°F. The pre-set temperature is 120 degrees, and you can adjust the temperature from the heater.

The water heater is wi-fi capable, so it allows you to operate from a smartphone. The control-R 2.0 mobile app features timers and schedules, and it also allows you to put it into vacation mode.

The compact design, and lightweight as it weighs only 45.6 pounds, lets you fix easily anywhere, even in small places. It does not have a built-in recirculation pump, so you need to wait for 10-15 seconds to receive the hot water. If you want instant hot water, then you need to buy a dedicated recirculation pump.

The V65iN has water-leak detection shut-off and anti-frost protection. If the temperature drops, the heater will start running at a low output of 98 degrees to save the pipe from freezing.

It consumes less amount of electricity thus saves your bill on electricity as well as on water. The product is approved by the South Coast Air Quality Management District.

Low NOx Tankless heater emits lower CO2, so it allows you to use it in all 50 states of the U.S.A., including California and Texas. This heater is suitable for a family of 4 residents. It comes with a 120 months warranty on heat exchanger, 60 months on residential parts, and 12 months on labor.

What we like
  • It is a lightweight and compact design that gives freedom to hang it wherever you want.
  • Low NOx technology emits lower CO2.
  • The heater has water-leak detection shut-off and anti-frost protection.
  • It is wi-fi compatible so that you can access it through a mobile app also.
What we don’t like
  • It does not have an in-built recirculation pump, so you need to purchase it separately.

3. Rinnai V75EN Outdoor Natural Gas Tankless Hot Water Heater

Rinnai V75EN Outdoor Natural Gas Tankless Hot Water Heater

This is Rinnai’s 3rd product in our review because the product made by them is durable, efficient, and lasts longer than its competitor. Rinnai V series consists of v94, v75, v65, and v53 models. We are going to review of v75EP heater.

Rinnai V75EN runs on natural gas, and the installation of a water heater needs to be done outside only. The product supplies hot water at the rate of 7.5GPM, and this figure varies upon the temperature of groundwater.

This gas tankless water heater allows you to run 2 showers, a dishwasher, and a washing machine altogether. This gas water heater is sufficient for a small family of 4.

It is wi-fi compatible so you can operate the timer and temperature from anywhere via the control-R 2.0 app. The product is lightweight as it weighs only 43.6 pounds.

It has leak detection and temperature lock features for safety purposes. Sadly, it does not come with a recirculation pump, and it will delay the hot water by 5-10 seconds. For instant hot water flow, you need to purchase the replicable pump separately.

The model has a BTU range of 10,300 to 180,000 BTU per hour, and you also need a 1/2 inch gas line in your house.

The energy factor of this model is 0.81 means the product is not highly efficient but not that bad in this price range.

The heater delivers 98°F – 120°F of hot water. When it runs on the high throttle, it emits a noise of only 55 dBA, which is less than the 2 people having a normal conversation. This model needs electricity to run. Rinnai ultra-low NOx water heater is SCAQMD compliant. Like other Rinnai models, it comes with 120 months warranty on the heat exchanger, 12 months warranty on labor, and 60 months warranty on parts.

What we like
  • It comes with a 10 years warranty like all other Rianna models.
  • It is SCAQMD compliant.
  • It has exceptional features like leak detection and temperature lock feature.
  • It supplies water at the rate of 7.5GPM.
What we don’t like
  • The replicable pump needs to be purchased separately.

4. Noritz NR50ODNG Natural Gas Outdoor Tankless Water Heater

Noritz NR50ODNG Natural Gas Outdoor Tankless Water Heater

Noritz is a Californian based company known for manufacturing innovative tankless water heaters and their accessories.

The Noritz NR50 model has a uniform energy factor of 0.81, making it a solid candidate in the gas tankless water heater among competitors. It supplies hot water at the rate of 5 GPM that is enough for 2 showers. It requires a minimum of 0.5 GPM to activate the water flow.

An exceptional feature I think about this tankless water heater can run on propane and natural gas.
It is suitable for outdoor installation, but you need to purchase the freeze protection kit separately. It delivers the heat from 115-140°F in the interval of 5.

It is super lightweight as it weighs only 33 pounds, and it is easy to install. The product has low NOx emission, so you can even use it indoors. As the model has low NOx emission, you can use it in all 50 states of America.

The dimensions of the product are 20.5x 13.8x 6.7 (Hx Wx D) inches, and it has a BTU range of 15,000 to 120,000 BTU.

Other features of the product include safety lockout, high-performance single flame burner, and thermal fuse for automatic overheat protection.

The heater comes with an exceptional warranty of 12 years on heat exchanger, 5 years on parts, and 1 year on labor.

What we like
  • It comes with 12 years of warranty.
  • It is lightweight and easy to install.
  • The heater delivers the heat from 115-140°F.
  • Ideal for outdoor.
What we don’t like
  • The freeze protection kit needs to be purchased separately.

5. Rheem RTG-84XLN-1 Natural Gas Tankless Water Heater

Rheem RTG-84XLN-1 Natural Gas Tankless Water Heater

Rheem was founded in 1925 by the Rheem brothers and it is currently the only manufacturer in the world that produces heating, cooling, water heating, pool & spa heating, and other heating products in one place. Rheem is one of the leading brands in the water heater.

Rheem RTG-84 is capable of supplying hot water at the rate of 8.4 GPM, and this rate is enough for running 3 showers at the same time. One of the biggest selling points is it requires a minimum activation flow rate of only 0.4 GPM. Other water heaters need a minimum of 0.5 GPM to activate the heater.

The exclusive water-saving setting helps the homeowner save up to 1100 gallons of water per year, and it has an energy factor of 0.81.

Exclusive overheat film wrap protects the heater from reaching dangerous temperatures, and the freeze protection protects the water heater up to -30°F. This water heater works on natural gas only.

EcoNet mobile app allows you to set the temperature from your smartphone. It also has a digital remote and thermostat to adjust the temperature and the timer.

The heater is capable of working at high altitudes up to 8,400 ft above sea level. It is environmentally friendly as it releases less fumes and meets the SCAQMD requirements.

The product is lightweight at 57 pounds, and the compact design is easy to install. The maximum water temperature is 140°F. Accessories are available to link the multiple units for load sharing.

The heater allows the homeowner for maintenance every 500 hours of use. The best part is it has a built-in recirculation pump, so you don’t need to wait for 10-15 seconds for hot water.

The heater comes with the 12 years primary warranty.

What we like
  • It comes with a 3 years warranty.
  • The freeze protection feature protects the water heater up to -30°F.
  • It weighs only 57 pounds.
  • It is capable of working at high altitudes of 8400ft above sea level.
What we don’t like
  • We weren’t able to find any suitable cons.

6. Takagi T-H3M-DV-N Natural Gas Tankless Water Heater

Takagi T-H3M-DV-N Natural Gas Tankless Water Heater

Takagi, based in Japan, is known for manufacturing durable gas tankless water heaters and giving warranty periods higher than global leaders.

Takagi T-H3M model delivers the hot water at the rate of 6.6 GPM, which is enough for running 2 showers. The product uses 1/2 inches gas supply valve along with inexpensive PVC to reduce the installation cost.

The model requires gas ranging from 19,500 to 120,000 BTUs. The product weighs only 49 pounds and can be installed inside the house without worries because it releases fewer fumes. It complies with Ultra-Low NOx regulation.

This gas tankless water heater is suitable for a small family of 3-4 people. It comes with an internal freeze protection system to prevent the system from getting damaged. The product also has an in-built recirculation system for your convenience.

Other features of this model include hydronic heating systems and radiant floor systems. The primary heat exchanger is made of copper alloy for 25 times better heat transfer than stainless steel. The secondary heat exchanger is made of superior 316L grade stainless steel.

Safety features of the model include freeze, overheat, surge protection, and troubleshooting diagnostics codes.
The model is made of condensing technology and works on natural gas. One thing I found fascinating is it has a uniform energy factor of 0.90.

Unfortunately, this unit does not come with any app or remote to set the timer. But another thing worth mentioning is it comes with a 15 years warranty on the heat exchanger and 5 years limited warranty on parts for residential use. For commercial use, it comes with 5 years limited warranty on the heat exchanger and the parts.

What we like
  • It comes with a 15 years warranty.
  • It has the highest uniform energy factor of 0.90.
  • It supplies the water at the rate of 6.6GPM.
  • Safety features of the model include freeze, overheat, surge protection, and troubleshooting diagnostics codes.
What we don’t like
  • The water heater cannot be operated by an app or remote; you need to select it manually.

What is a Gas Tankless Water Heater?

In simple terms, the gas tankless water heater does not have a tank to store hot water. This water heater supplies hot water on demand and it uses natural gas as its fuel source. Gas tankless water heaters take up less space because it does not need any storage.

They directly heat the hot water when cold water travels through the pipe by burning the gas inside the chamber. This saves your space of storage and also supplies the constant hot water.

The gas tankless water heater has a slightly higher price than the tank water heater, but their life expectancy is double, and they are more efficient than the tank water heater.

How does a gas tankless water heater work?

Like the tank water heater, it does not store the water in the tank. When you turn the tap of hot water on, the cold water travels through the unit via the pipe. The water heater hits the water by a gas burner and it will adjust the flames to maintain the proper temperature throughout the process.

The gas tankless water heater constantly supplies hot water, but it has an output limit.

Difference Between Tankless water heater and Tank water heater:

Tankless water heaters supply the hot water on demand whereas a tank water heater stores the hot water in the storage tank and supply it whenever someone turns on the faucet or any other water-related appliances.

The tankless water heater is compact in design, lightweight, and takes up less place. On the other hand, the tank water heater needs a storage area to store the water.

The tank water heater burns the flames when the water in the storage cools down whether you need hot water or not. This increases the electricity bill that you haven’t consumed. But a tankless water heater heats the water on demand, so the unit will start working when you turn on the faucet or any other water appliances.

The life of a tank water heater is 8-10 years, and the life of a tankless water heater is between 15 to 20 years. The tankless water heaters are more efficient than the conventional type of water heater.

Features come with a price tag. The cost of a tankless water heater is twice the price of a tank water heater.

Benefits of Gas Tankless Water Heater

Gas Tankless Water Heater Guide

There are various benefits of using a tankless water heater. We will discuss the benefits in detail here:

Need less space:

The tankless water heaters are compact, lightweight, and smaller in size than the tank water heater. The tankless water heater doesn’t need storage to store the hot water. Tankless heaters work on the concept of hot water on demand.

The standard size of tankless water heaters is 28 inches tall, 20 inches wide, and 10 inches deep.

High life span:

The life expectancy of a tank water heater is 8-10 years, and compared to the lifespan of a tankless heater is very low. The lifespan of a tankless water heater is about 15-20 years, and if used with proper care, it can work efficiently for up to 25 years.

Energy-efficient:

The tankless water heaters are cost-efficient compared to the tank heaters. A tank water heater heats the water continuously, while a tankless water heater heats water when needed. The tankless water heater helps you to save 30% energy compared to the traditional water heater.

Low Maintenance:

Tank water heaters require annual maintenance, and in some regions where excess hard water is present, it is recommended to service once every 6 months. Tankless water heater does not need maintenance for 3-4 years, but it is recommended to perform maintenance every year.

You don’t need to call experts for maintenance in a tankless water heater. With a few easy steps, you can perform it efficiently.

Never-ending water supply:

In heavy water usage, the tank water heater with limited storage will run out quickly. The tankless water heater serves hot water on demand, so you don’t need to worry about the water storage when using a shower or any other appliances.

What to look for when buying a gas tankless water heater

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The whole house water heater is not a luxury but a necessity. Choosing the best gas tankless water heater is a tedious and stressful task. To make your work easy, we have developed a buying guide.

When buying a tankless water heater, you need to keep the following points in your mind:

Water Flow rate:

The flow rate is determined based on the capacity of producing hot water by a gas tankless water heater. This value is measured in the GPM or Gallon per Minute. The flow rate of 5 to 6 GPM is enough for a family of 4 members. On average, a shower needs 3GPM, so with the flow rate of 6GPM, you can easily run 2 showers simultaneously or 1 shower and a washing machine.

For a larger family, you will need a flow rate of 8-10 GPM of water. Evaluate your water usage before making a buying decision. In the morning, the water usage is high because children have to get ready to go to school and you have to get ready for the office. If the flow rate is low, the heater won’t be able to produce enough hot water when multiple showers are running.

Weight:

The tankless water heaters are lightweight and have a compact design. Although, compare the weights before purchasing the tankless heater. If you are looking for a heater that delivers 6-8 GPM of water, you can easily find that in below 50 pounds. Lightweight heaters are easy to install.

Built-in recirculation pump:

The responsibility of the recirculation pump is to give instant hot water when anyone turns the faucet or shower. In the absence of a recirculation pump, you need to wait for 10-15 seconds to receive the hot water. Some heaters come with a built-in recirculation pump to serve hot water every time you open the knob of the faucet without any delay.

You can also install the replicable pump separately. Another advantage of having a recirculation pump is you will save gallons and gallons of water, and that will reflect in your water bill.

They are a little more expensive than the water heater that comes without a recirculation pump. If you are OK with waiting for 10-15 seconds, then go for the heater without a recirculation pump.

Energy efficiency:

The gas tankless water heaters are more efficient than the tank water heater. The family that uses 41 gallons or less in a day will save up to 30% energy compared to the tank water heater. Large families that use around 80 gallons per day will save up to 12% of energy. This efficiency is possible because they prevent the standby loss caused by the tank water heater to keep the water warm.

As per the ENERGY STAR estimate, a family can save up to $100 if they use a gas tankless water heater. Despite the higher cost of the heater and installation, you will cover up the money in the long run.

Wi-Fi Compatible and digital remote:

Now everything is possible through a smartphone, and the gas tankless water heaters are not far from that. Many gas tankless heaters are Wi-Fi compatible, allowing you to change the timer, schedule for heat water, and even put the heater remotely on vacation mode. These features are only available with the top brand’s heaters.

The heater also comes with a digital remote for your convenience. If the heater is not Wi-Fi compatible, you can make changes via a digital remote.

Low-NOx technology:

The low-NOx tankless water heater releases fewer emissions and allows you to use it in all 50 states. You can install the heater inside your house as they are not harmful. NOx is an abbreviation of Nitro Oxide. If you reside in Texas or California, make sure to check whether the gas tankless heater is compliant with low-NOx emission or not.

Other Features:

Many gas tankless water heaters have some additional features that can be useful to you. A feature like anti-leak detection detects the leak and automatically shuts off the water supply. In the region where the temperature is likely to go near 0-degree or minus, the feature like anti-frost protection saves the pipeline from getting blocked by keeping it warm.

Warranty:

Out of all other features, the best part of owning the gas tankless water heater is the warranty period. The warranty period starts from 10 years and goes up to massive 15 years on the heat exchanger. Rinnai gives 10 years warranty, whereas the Japanese manufacturer Takagi gives 15 years warranty.

The manufacturers also give 5 years warranty on parts and 1 year on labor. We agree that the gas tankless water heater is twice the price of a tank water heater, but this warranty period and energy efficiency will cover the cost in just a few years.

FAQ

Q. How do I choose a water heater capacity?

To evaluate the water heater capacity, you need to follow some steps. First, you need to determine the daily usage. If the daily usage is low, then you can select the gas tankless water heater that delivers the hot water at the rate of 5-6 GPM. Your water requirement is low, but you need to run multiple showers and faucets simultaneously than you need the water heater that delivers the hot water at the rate of 8-10 GPM.

Q. What size gas tankless water heater do I need for a family of 5?

It depends on your usage. If you need to run multiple showers at once, then it is advisable to purchase the water heater that serves hot water at the rate of 8-10 GPM. If you can manage the usage, then the heater producing 5-6 GPM is enough.

Q. How much does it cost to have a tankless water heater installed?

The cost including, the unit, installation, labor, and other charges, falls between $1200 to somewhere $5000.

Q. Do gas tankless water heaters need maintenance?

The Gas tankless water heater needs very little maintenance compared to the tank water heater. They require maintenance every 3-4 years, but it is advisable to perform the maintenance every year. Maintenance is easy, and you don’t need to call experts.

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