Best Natural Gas Tankless Water Heaters

Best Natural Gas Tankless Water Heaters

  Best One Overall  

The Rinnai RUR98iN Review2
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Based on the reviews, the best on-demand water heater overall should be the Rinnai RUC98iN which has the biggest range of BTU (British Thermal Unit) and Temperature selection. Compared to Navien NPE 240A, it is slightly lighter in weight and affordable.

>> Read Our Review of The Rinnai RUC98iN

  Best One for The Money  

Takagi T-K4-OS-NG
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Judging from the reviews, the best tankless water heater for the money should be the Takagi T-K4-OS-NG, which is the lightest among the heaters on the list. The price is quite affordable and its performance is above average. Furthermore, venting is not required with this product.

>> Read Our Review of The Takagi T-K4-OS-NG

Nowadays, Tankless water heaters appear to be the best solution to the increasing demand for efficient water heaters in the construction industry. The replacement of standard tanked water heaters with the best tankless water heaters has made it possible for homeowners to set their energy bills right. Besides low energy bills and endless hot water on demand, the unit is less costly, environmentally friendly and saves space.
Tankless water heaters are available in three power sources: Natural gas, propane and electricity. If you choose the natural gas type, then you need to be aware of your local codes, water quality, gas line and electric connection, and water consumption.
There are different brands of Natural gas tankless water heater in the market. However, choosing the best among them will let you enjoy unrestricted hot water supply. In this review, we will introduce 7 of the best Natural gas tankless water heaters.

Rinnai RUC98iN

Rinnai RUC98iN Ultra Series

Design Feature

Rinnai RUC98iN Ultra Series is a top-rated tankless water heater. The unit comes with a condensing technology that requires the use of two heat exchangers. The tankless gas water heater has an energy factor of 0.95. Designed for indoor installation, the unit can be used for both residential and commercial purposes. It is compact in design and weighs 61.7 lbs.

The Rinnai RUC98iN Ultra Series natural gas tankless water heater uses 15,200 to 199,000 BTU’s. of Natural gas to deliver an endless supply of hot water at a flow rate of 9.8 GPM for a temperature rise of 30 °F. The unit uses electricity which requires a voltage capacity of 120 volts to power the Electronic Ignition circuit.

The natural gas tankless water heater comes with a factory set temperature range of 98 °F to 140 °F and 98 °F to 185 °F for residential and commercial applications respectively. It also comes with an MC-91-2US controller that can be used to make output temperature settings. The unit works as designed with a ¾inch gas Flex line and allows for concentric or twin pipes venting.

In matters to deal with safety, the Rinnai RUC98iN Ultra Series operates with Ultra-low NOx emissions and also meets California and Texas NOx Emissions Standards. In addition, the unit is compatible with a range of Rinnai digital controllers.

The residential warranty offers a 12-year limited cover for the Heat exchanger, a 5-year cover for the Parts and a year cover for Labor. On the other hand, the commercial warranty offers a Limited 5-year warranty on heat exchanger, 5-year on parts and 1-year on labor.

  Pros  

  • Space-saving design

  • Certified by Energy Star

  • No standby energy losses

  • Easy to install

  • Low energy and utility bills

  • Quiet operation

  • Constant, endless hot water

  • Ultra-low NOx emissions

  • Approved by SCAQMD

  • Nice customer support team

  Cons  

  • Waste lots of water as one wait for the water to heat up

  • A very slight decrease in water pressure

  • Costly installation cost

User Critic

The output water flow will depend on the input water temperature or the temperature rise required. This is means, you are likely to get a flow rate of 9.8 GPM when your input water temperature is 55 °F.

Final Verdict

This Rinnai tankless is the best tankless gas water heater for residential or commercial. It can also be used for space heating. Since it meets Texas and California NOx emissions standards, the unit is fit to be installed in these states.

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Takagi T-KJr2-IN-NG

3. Takagi T-KJr2-IN-NG

Design Features

The Takagi T-KJr2-IN-NG tankless gas water heater has a design that only fits for indoor installation. It has an energy factor of 0.82 or an efficiency of 82%. The top-rated tankless water heater has a compact design and weighs 38 pounds. It is designed for a domestic hot water system and heating systems.

The natural gas tankless water heater uses 19500 BTUs to 140000 BTUs of Natural gas to deliver hot water at a flow rate of 6.6 GPM with a temperature rise of 35 °F; a minimum flow rate of 0.5 GPM to activate it. Since it uses electric Ignition, the product requires an electrical rating of 120V to initiate the process.

For the tankless water heater to operate properly, it requires a 3/4-inch gas line and a 4-Inch category III stainless steel pipework for direct venting. The unit comes with a power vent which automatically adjusts the gas supply depending on the demand. The material used on the heat exchanger is copper. It comes with a TK-REO2 remote control and a power code.

It comes with an easy to install and use digital thermostat in addition to a monitoring and controlling mechanism that uses inlet and outlet thermistors to maintain constant temperatures. The temperature settings on the display range from 99F to 167F. The safety features include Protection from a surge, overheat and freeze.

The Takagi T-KJr2-IN-NG tankless water heater comes with a separate warranty for a residential and commercial application. If used for residential application, the company can cover for the heat exchanger and parts for up to 15 and 5 years respectively. For commercial purposes, it comes with a warranty of 5 years for the heat exchanger and 3 years for the parts.

  Pros  

  • Small, compact and lightweight

  • Saves space

  • No standby energy losses

  • Provides continuous supply of hot water

  • Environmentally friendly

  • Certified by Energy Star

  • Easy to install

  • Reduced natural gas bill

  Cons  

  • Requires a professional technician

  • Expensive installation

  • Slight humming and rumbling noise during operation

User Critic

According to consumer reviews, the temperature of the inlet water can affect the flow rate, that is, the higher the temperature rise the lower the flow rate you get. The unit can take about 30 seconds for output water to reach the set output temperature.

The unit could be expensive for homeowners who are using a 1/2-inch gas line because this unit requires a 3/4-inch gas line connection. In addition, the unit is affordable, but it gets costly as you purchase all the accessories needed and pay installation fees. It is important to note that the warranty is void if you install the unit without the assistance of a licensed technician.

Final Verdict

It is suitable for a light residential and radiant heating applications in small and medium-sized apartment units. If you are looking for a unit that can handle two showers running at the same time in a warmer climate and 1 shower in cold climate, then this suits you well.

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Rinnai V65IN

Rinnai V65IN

Design Feature

The Rinnai V65IN is one of the top-rated tankless gas water heaters. It is designed for indoor installation and certified for installation in manufactured (Mobile) homes. It has an energy factor of 0.82 and a compact design with a weight of 49 pounds.

This gas water heater uses between 10,300 and 150,000 BTUs of Natural gas to deliver endless hot water at a flow rate of 6.6 GPM. It can be activated by a flow rate of 0.4 GPM. The unit uses electricity for ignition purpose which, it requires a voltage capacity of 120 (60 Hz).

This unit comes with a minimum and maximum factory preset temperature of 98 °F and 120 °F. With the Rinnai MC-91-2US Standard Remote, you can adjust the temperature up to a maximum of 140°F. It is compatible with Rinnai digital controllers and comes with an integrated error code detector.

As a safety measure, the unit comes with an enhanced scale and Leak detection mechanism that automatically shuts off water to the unit and prevents it from damage. It also comes with a temperature lock that restricts unauthorized changes to prevent an accidental increase in water temperature.

Since it is the Rinnai V65IN is an Ultra-Low NOx Series tankless gas water heater, it uses advanced technology that makes it environmentally friendly. In addition, it complies with South Coast Air Quality Management District 14 ng/J or 20 ppm NOx emission levels and also meets California and Texas NOx Emissions Standards.

The gas and water supply connections will require a 3/4-inch pipework. Since this is a non-condensing with Direct venting, it requires the use of an aluminum interior vent pipe with a PVC outer pipe. The unit comes with a 10-Year Warranty on Heat Exchanger, 5 Year on Parts, and 1 Year on Labor.

  Pros  

  • No standby energy losses

  • ENERGY STAR certified

  • Lightweight and Compact

  Cons  

  • Takes longer to get the water hot

User Critic

According to consumer reviews, you will have to wait for up to 40 seconds for the water to get hot to the set temperature. House owners with a 1/2 gas line will have to endure an additional cost of running a new line of ¾ inches. The 6.6 GPM flow rate is obtained from a small temperature rise, so a cold well water could deliver 3.3 GPM of hot water.

Final Verdict

Rinnai V65IN is the best tankless gas water heater for a house with 2-bathrooms or less. If you are looking for a tankless gas water heater that can handle two showers and a washing machine running at the same time or one shower, dishwasher and a washing machine, all running at once, then this w.

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Takagi T-K4-OS-NG

Takagi T-K4-OS-NG

Design Feature

The Takagi T-K4-OS-NG tankless gas water heater is an improvement to the T-K3 model. It is designed for outdoor installation and domestic hot water systems. The unit is also rated for use with storage tanks, hydronic heating systems, recirculation system, radiant floor system and heating application.

The natural gas tankless water heater comes with an energy factor of energy factor of 0.82. Its ultra-compact design, which allows for wall mounting, gives it a weight of 38 lbs. The unit requires 11,000 to 190,000 BTU per hour of natural gas to deliver endless hot water at a flow rate of 8 GPM for a temperature rise of 35°F. the unit requires a minimum flow rate of 0.75 GPM to activate it.

The unit comes with a TK-RE02 remote temperature controller which not only adjusts the temperature settings but displays diagnostic error codes. It comes also comes with a digital thermostat with maximum factory preset temperature of 122 °F, which by overriding gives a temperature range of 99 °F to 167 °F.

The top-rated tankless water heater has a built-in power venting system, so it does not require venting. The unit maintains a constant water temperature due to the use of Inlet and outlet thermistors which assist in temperature monitoring. It also has a Built-in freeze protection technology that protects the unit from extremely cold temperatures.

As for safety, the unit features a surge, overheat and freeze protection and maintenance codes. The unit requires an electrical rating of 120V to power the control board and Electric Ignition system. The unit requires ¾ inch pipework for both the water and gas connections.

The T-K4-OS tankless gas water heater can be used for both residential and commercial applications. If used for residential purposes, the company give a warranty cover of 5 years for the heat exchanger, 3 years for parts and 1 year for labor. For the commercial purpose, the company gives a 3-year warranty on the heat exchanger and 1-year warranty on all other components.

  Pros  

  • saves up to 45% on their monthly gas bills

  • No standby energy losses

  • approved by Energy Star

  • saves lots of space

  • yearly heating bill has gone down to 20%

  Cons  

  • Slight hum during operation

User Critic

The best on demand water heater requires electricity to operate, unless you have a back up system when power fails you won’t have hot water. It is best if the unit is installed by a professional not to void the warranty.

Final Verdict

The Takagi T-K4-OS-NG is the best tankless gas water heater for a house with up to 3 bathrooms and a kitchen since it can handle 3 showers running at the same time with constant temperature during warmer climates and 2 showers during cooler climate. This unit will cost you $849.90.

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Rheem RTG-64DVLN

Rheem RTG-64DVLN

Design Feature

The Rheem RTG-64DVLN is a Low NOx series of tankless gas water heaters. It uses a condensing technology with a new generation burner. The unit has been designed for indoor installation and residential application only. The compact design gives it a weight of 54 pounds. It uses Next generation burner technology. This unit has an energy factor of 0.82.

The top-rated tankless water heater uses 11000 to 150,000 BTU of Natural gas to deliver hot water on demand at a flow rate of 6.4 GPM for a temperature rise of 35 F. The unit requires an electricity rating of 120 VAC for the ignition system, power control board and other digital features. The unit can be activated by a minimum flow rate of 0.40 GM.

The unit has a built-in electric blower and a self – diagnostic system for easy installation. It comes with an intelligent electric control. This tankless gas water heater also comes with a UMC-117 remote control and 10-Feet of thermostat wire. The thermostat displays temperature settings and diagnostic codes.

The EZ-Link cable is also available for high demand applications – works by connecting two tankless units to operate as one unit. The maximum factory preset temperature of the unit is 120 °F, but with the UMC-117 remote control, you can achieve a temperature range of 85 °F to 140 °F. It is also designed for Freeze protection to up to a temperature of -30 °F.

The natural gas tankless water heater is designed for direct venting with concentric Category III Coaxial Stainless-Steel pipework. It also requires the use of a 3/4-inch gas line and a 3/4-inch water input and an output connection for efficient flow. The warranty of the unit offers a 12-year coverage for the copper heat exchanger, 5 years of parts and 1 year for Labor.

  Pros  

  • Approved by SCAWMD

  • Certified by ENERGY STAR

  • Environmentally friendly

  • No standby energy losses

  • A continuous supply of hot water

  • Energy efficient

  • Saves space

  • Easy to install

  • Unlimited hot water

  • Monthly gas bill drops of up to 50%

  • Top-notch quality product

  • Fires up quickly

  • Operates quietly

  • Certified by gama

  Cons  

  • Costly installation

User Critic

Most houses use a ½ gas line, so it would be costly to rerun a 3/4 gas line which is the required size for the unit. The manufacturer recommends that the tankless water heater is installed by a licensed, state qualified and trained technician, which comes at a cost and failure to adhere will void the warranty.

The unit takes about 30 seconds or more to get the water hot. The flow rate is indirectly proportional to the rise in temperature, this means you will get a flow rate of 5.6 GPM for a 45 °F rise and 3.3 GPM for a 77 °F temp rise.

Final Verdict

Rheem RTG-64DVLN is the best tankless gas water heater for a house with 2 full bathrooms and a kitchen since it has shown to handle two showers at the same time.

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Rheem RTGH-95DVLN

Rheem RTGH-95DVLN 9.5 GPM

Design Feature

The Rheem RTGH-95DVLN falls in the Low Nox tankless gas water heater series. It is designed for indoor installation only and approved for domestic hot water systems. It can be used for residential and commercial applications. The use of the condensing technology in this unit gives it a 94 % Energy efficiency.

The top-rated tankless water heater uses up to 199,000 BTU/H of Natural gas to deliver unlimited hot water supply at a maximum flow rate of 9.5 GPM for a temperature rise of 35 °F. The unit comes with a maximum factory preset temperature of 120 °F and can be raised to 140 °F with a manual override. The unit requires an electrical rating of 120 V (60 Hz) to power the digital remote controller, the power control board and ignition system. The tankless gas water heater can be activated and operated by a minimum flow rate of 0.40 GPM and 0.26 GPM respectively.

The unit comes with a Digital remote control and 10 ft. of thermostat wire to be used for setting output water temperature and displaying fault codes. The manufacturer adds an EZ-Link cable which is to be used for high hot water on demand applications. It also comes with a Digital display which shows the temperature setting and diagnostics codes. The use of a recirculating pump and hot start programming is aimed to minimize cold water bursts. 

Rheem RTGH-95DVLN is designed with a Self-diagnostic system that makes the installation process easy and manageable. There is a Built-in electric blower in the design of the tankless water heater. The condensing technology comes with a dual, stainless steel heat exchanger.

The tankless hot water heater is designed with a freeze protection mechanism that can handle temperatures as low as -30°F. It has integrated Intelligent electronic controls designed to not only increase the energy efficiency but safety too. It also has a built-in condensate neutralizing kit and inlet water filter.

The Natural gas tankless water heater is designed for direct venting with a 3-inch Solid core PVC pipework for both the intake and exhaust vents. The unit requires a 1/2inch ID flex pipe for the gas line connection and 3/4inch for the water line connections. The unit comes with a 12-year warranty on the Heat exchanger, 5 years on the Parts, and 1 Year on Labor. The product life of the Rheem RTGH-95DVLN is rated at 20 years.

  Pros  

  • No standby energy losses

  • Condensing for efficiency

  • saves space

  • very easy to maintain

  • easy to install.

  • Water temp is consistent

  • endless hot water

  • listed by AHRI

  • SCAQMD compliant

  • Energy Star certified

  Cons  

  • inquired about installing a circulation pump

  • the complexity of the installation

  • low rumbling when turned on low persistent rumble for a few minutes or two

  • operates with a faint low-pitched sound

User Critic

The installation can be costly especially when you have to run a new ¾ inch gas line to replace the ½ inch one. Judging by reviews from customers, the unit has an unstable heat exchanger which can fail after 2 years of use. Another common drawback is that of hot water taking long to deliver hot water with the set output temperature- it can take up to 2 minutes to get to the nearest faucet which is slightly longer.

The unit does not operate without electricity, so when the power is out, you won’t have hot water. Therefore, you would need a stand-by electric generator to serve you during the power outages.

Lastly, failing to reconfigure the vent pipes such that the exhaust is not getting sucked back into the intake will make your unit noisy with a bit of hammering when it runs.

Final Verdict

Rheem RTGH-95DVLN is the best tankless gas water heater suitable for a house with 3 Bathrooms. It can handle up to 3 showers running at the same time. The unit can run simultaneously two showers, the dishwasher, and two sinks with hot water without a loss in water temperature.

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Navien NPE-240A

Navien NPE-240A

Design Feature

The Navien NPE-240A falls in the Low NOx emissions tankless gas water heater series. It is designed for domestic water heating and indoor or outdoor installation. It comes with an Energy Factor of 0.97, which translates to an efficiency of 97%. It is compact in design with a weight of 82.0lbs.

The tankless gas water heater uses 19,900 to 199,900 BTU/H of natural gas to deliver an unlimited supply of hot water at a maximum flow rate of maximum water flow rate of 11.2 GPM for a temperature rise of 30°F. A minimum flow rate of 0.5 GPM is required to activate the unit. The top-rated tankless water heater comes with factory pre-set temperature of range of between 98 °F to 140 °F, but using the control panel the temperature can be set to operate under the Commercial Mode which offers up to 182 °F. It also requires a voltage capacity of 120 volts, 60Hz, with a wattage of 200 watts to run the Electronic ignition circuit and the external pump.

The unit has a field convertible gas system which requires a dedicated 3/4-inch gas line. The water inlet and output connections require a 3/4-inch pipework connection for it to operate efficiently. The recommendable venting type is Forced draft direct vent with a PVC pipe work line of 2 inches.

The Navien NPE-240A natural gas tankless water heater comes with a “Comfort Flow” technology that uses a built-in Internal insulated buffer tank and recirculation pump. This technology is supposed to eliminate a cold-water sandwich effect which is common in many tankless hot water heaters. It also has a high-altitude capability.

The Navien NPE-240A comes with an Intelligent preheating technology which allows the unit to know when hot water is used and does a pre-heating; it can be activated by accessing the dip switch. It also has the Condensing technology which uses two stainless steel heat exchangers which are both responsible for its ultra-efficiency.

The unit warranty for residential use offers a 15-year coverage on the heat exchanger, 5 years on parts and 1 year on Labor. On the other hand, the commercial warranty offers 8 years for the stainless-steel heat exchanger, 5 years for parts and 1 year for labor.

  Pros  

  • Approved by Energy Star

  • low energy and utility bills

  • Constant hot water

  • high-quality unit

  • No standby energy losses

  Cons  

  • Noisy when it heats up

  • Requires additional parts (thermocouple and a microcontroller)

  • Hot water takes long

User Critic

The Navien’s warranty will be voided in the event that you purchase the unit from an unauthorized supplier or dealer, make improper installations, modify or alter the product and use product for space heating purposes.

Even with a The Comfort Flow technology, most users complain of alternating hot and cold temperatures during the course of taking a shower. Furthermore, attempting to increase the temperature would only increase the temperature swings.

If you are using it for a 2-story house, then you will have to wait for about 30 seconds for the water to get hot. The flow rate of the unit is indirectly proportional to the temperature rise, this means, with a temperature rise of 45°F the unit offers a flow rate of 8.7 GPM and with a temperature rise of 70 °F, you get 5.6 GPM.

Final Verdict

Navien NPE-240A is the best tankless gas water heater suitable for a 2 to the 3-bathroom house since it can handle three standard showerheads running simultaneously or two showers with the dishwasher or washing machine running.

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Specifications

Rinnai RUC98iN

Takagi

T-KJr2-IN-NG

Rinnai V65IN

Takagi

T-K4-OS-NG

Rheem

RTG-64DVLN

Rheem

RTGH-95DVLN

Navien NPE-240A

Usage

Indoor

Indoor

Indoor

outdoor

Indoor

Indoor

Indoor/outdoor

BTU Range

15,200 -199,000

19,500-140,000

10,300 -150,000

11,000 -190,000

11,000 – 150,000

11,000-199,900

19,900 – 199,900

Max Flowrate (GPM)

9.8

6.6

6.6

8

6.4

9.5

11.2

Temp range

98°F to 185°F

99°F to 167°F

98°F to 140°F

99°F to 167°F.

85°F to 140°F

85°F to 140° F

98°F to 140°F

Energy factor

0.95

0.82

0.82

0.82

0.82

0. 94

0.97

Weight lbs.

61.7

38

49

38.0

54

79

82

Price

$1,317.50.

$546.00

$674.85

$849.90

$731.24

$1,400.00

$1,612.98

Tankless Water Heater Gas Vs Electric

Most top-rated tankless water heater use gas or electric power sources. When comparing which is the best tankless water heater between gas and electric, it is important to look into the requirements of each unit.

Most gas water heaters require additional installations like the venting pipework and use of an appropriate gas line. It could be easy to install an electric tankless water heater since it requires less components, however the installation would be a bit costly. Upgrading a gas line is cheaper than doing so for an electric system.

The tankless gas water heater uses a cheaper source of energy. Energy loss in gas tankless water heaters is minimal due to the condensing technology which uses two heat exchangers.

The electric water heater has no emissions making it more environmentally friendly. The high cost of electricity is felt when there is high hot water on demand.

The best on demand water heater should serve the whole house system of a large family. The gas type tankless water heater offers a higher flow capacity during the climate season. In this case, using an electric heater will create the cold-water sandwich effect.

 

Summary
Best Natural Gas Tankless Water Heaters
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Best Natural Gas Tankless Water Heaters
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We reviewed one of the Best Natural Gas Tankless Water Heaters out there.
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WaterHeaters.Review
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