10 Natural Gas Water Heater Vs Electric of 2026 To Cut Operating Costs

1

Rheem RTG-84XLN-3 High Efficiency Non-Condensing Outdoor Tankless Natural Gas Water

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  9.7
• Brand
  Rheem

Key specs2

Outdoor Cabinet Setup

Exterior wall mounting frees up interior utility space and removes the expense of cutting exhaust penetrations through the roof or sidewall.

Simultaneous Fixture Support

3 to 4 showers running together

Pros & cons43

Pros

• Delivers up to 8.4 GPM at a 35 degree rise to supply 3 to 4 showers at once
• Outdoor exterior mounting eliminates the cost of indoor exhaust vent ducting
• Durable metal cabinet includes factory-installed freeze and flame failure protection
• Backed by a 15-year heat exchanger warranty and a 5-year parts warranty

Cons

• Outdoor-only mounting requires exterior gas and water line routing
• Requires professional installation and lacks integrated wireless app support
• Non-condensing 0.82 UEF rating is lower than condensing gas alternatives

2

Rheem RTG-70XLN-3 High Efficiency Non-Condensing Outdoor Tankless Natural Gas Water

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  9.3
• Brand
  Rheem

Key specs2

Venting Requirements

Zero indoor venting needed

Hot Water Capacity

The 160,000 BTU gas burner supports mid-sized homes by delivering continuous hot water across 2 to 3 plumbing fixtures at a 35 degree temperature rise.

Pros & cons43

Pros

• Supplies 7.0 GPM at a 35 degree rise to run 2 to 3 showers simultaneously
• Outdoor wall-mount design bypasses indoor direct venting expenses entirely
• Precise digital LED temperature panel allows adjustments in 1-degree steps
• Built-in freeze protection guards internal components against cold weather

Cons

• Lacks built-in WiFi connectivity for remote diagnostics or adjustments
• Provides 160,000 BTU which delivers lower peak flow than 8.4 GPM models
• Outdoor installation is unsuitable for areas without exterior utility line access

3

APUS Natural Gas Tankless Water Heater, 140,000 BTU, Up to

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  9.1
• Brand
  APUS

Key specs2

Circulation System

An internal booster pump and single-circulation design help accelerate hot water delivery to remote taps without requiring an external add-on pump.

Operating Noise Design

Bottom turbo fan runs 30% quieter

Pros & cons43

Pros

• Built-in booster pump increases water flow by up to 130 percent to hit 6.8 GPM
• Single-circulation technology reduces waiting time for hot water at the tap
• Smart Season Comfort Mode automatically adjusts output based on incoming water temp
• Operates at 30 percent lower sound levels with a bottom turbo fan design

Cons

• Requires an active 120V AC electrical outlet nearby to run the pump and controls
• Uses 1/2-inch NPT connections which may require plumbing adapters on 3/4-inch lines
• The 0.81 UEF rating provides standard non-condensing efficiency rather than peak tier

4

Rheem RTG-70DVLN-3 High Efficiency Non-Condensing Indoor Tankless Natural Gas Water

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  8.9
• Brand
  Rheem

Key specs2

Internal Leak Detection

Integrated LeakGuard sensors detect water inside the cabinet early, helping protect finished interior spaces like basements or utility closets from water damage.

Direct Vent Installation

Dedicated indoor venting required

Pros & cons43

Pros

• LeakGuard detection system alerts you and mitigates risk from internal leaks
• Direct vent indoor configuration allows safe placement inside basements and closets
• Delivers 7.0 GPM at a 35 degree temperature rise to power 2 to 3 showers at once
• Features a 15-year heat exchanger warranty and 5-year parts protection

Cons

• Requires dedicated indoor direct vent pipe runs through an exterior wall or roof
• Weighs 46.5 pounds, making it heavier than comparable compact indoor units
• Does not include smart app connectivity on the standard model

5

APUS Tankless Water Heater Natural Gas, Up to 4.42 GPM,

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  8.6
• Brand
  APUS

Key specs3

Low Flow Activation

Starts heating at 0.66 GPM

Sound Rating

36 dB quiet operation

Freeze Drain Requirement

Internal freeze protection engages automatically, but the unit must be fully drained if left unpowered or unused near 41 degrees F to prevent cracking.

Pros & cons43

Pros

• Low-flow startup activates heating at just 0.66 GPM for single-sink demands
• Compact 19.18-pound cabinet fits tightly into small utility spaces and apartments
• Quiet 36 dB operation minimizes audible burner noise in living areas
• Oxygen-free copper heat exchanger reaches up to 98 percent thermal efficiency

Cons

• Limited 4.42 GPM capacity cannot handle more than 2 showers and 1 sink together
• Must be manually drained when ambient temperatures stay near or below 41 degrees F
• Lower 95,000 BTU input produces lower flow rates in regions with freezing groundwater

6

Rheem RRTGH84DVLN3701171 Rheem RTGH Series 8.4 GPM 157,000 BTU 120

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  8.4
• Brand
  Rheem

Key specs3

Condensing Efficiency

0.93 Uniform Energy Factor (UEF)

Emissions Standard

Ultra-low NOx compliant

Gas Savings Profile

A 0.93 UEF extracts extra heat from exhaust gases, delivering high whole-house flow with lower BTU gas demand than standard non-condensing heaters.

Pros & cons43

Pros

• High-efficiency condensing system delivers a 0.93 UEF to minimize monthly gas use
• Provides 8.4 GPM at a 35 degree rise using a modest 157,000 BTU burner
• Meets ultra-low NOx standards for reduced household combustion emissions
• Supplies sufficient hot water for 3 to 4 simultaneous shower runs

Cons

• At 59.88 pounds, this is the heaviest indoor unit in the comparison
• Condensing technology requires a drain line for acidic condensate disposal
• Standard configuration lacks wireless app connectivity for remote control

7

ThermoMate CZ422NG, 102,000 BTU 4.7 GPM Natural Gas Tankless Water

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  8.3
• Brand
  thermomate

Key specs2

Vent Connection Size

3-inch OD vent port

Safety Protections

• Automatic freeze guard active at 41 degrees F
• Boil-dry, flame-out, and overheat shutoffs
• Pipe blockage and air pressure monitoring

Pros & cons43

Pros

• Standard 3/4-inch water connections and 3-inch OD vent connection simplify piping
• Smart chip adjusts heating 20,000 times per second for stable water temperatures
• Compact 22-pound chassis mounts easily in confined indoor utility closets
• Built-in 3.5-inch LED display clearly presents error codes and flame status

Cons

• Peak output of 4.7 to 5 GPM limits simultaneous use to roughly two fixtures
• Freeze protection starts at 41 degrees F and requires power to remain active
• The 0.81 UEF rating does not match the efficiency of condensing competitors

8

Ranein Natural Gas Tankless Water Heater, 8.5 GPM, 190,000 BTU,

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  8.2
• Brand
  Ranein

Key specs2

Elevation Limit

Not recommended above 2,000 feet

Combustion Blower

The bottom-mounted blower modulates speed dynamically against changing outside wind pressure, ensuring proper oxygen supply and preventing exhaust backflow.

Pros & cons43

Pros

• High-output 190,000 BTU burner supplies up to 8.5 GPM across 4 to 6 outlets
• Underneath blower fan adjusts speed to wind pressure to prevent smoke backflow
• Standard 3/4-inch NPT water connections match common household plumbing lines
• Compact 24.25-inch tall frame saves significant floor space over 50-gallon tanks

Cons

• Manufacturer does not recommend operation in locations above 2,000 feet elevation
• Limited 2-year warranty period is shorter than major brand offerings
• Requires manual opening of the pressure relief valve to drain water before freezes

9

MIZUDO Natural Gas Tankless Water Heater, 199,000 BTU, Indoor

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  7.8
• Brand
  MIZUDO

Key specs2

Maximum Delivery Rate

10.3 GPM at 199,000 BTU

Smart Controls

Built-in WiFi links with a mobile app and Amazon Alexa, letting you monitor system status, track alerts, and adjust target temperature remotely.

Pros & cons43

Pros

• Maximum 10.3 GPM output and 199,000 BTU capacity handle high whole-home demand
• Smart WiFi and Alexa compatibility enable remote monitoring and app adjustments
• Low-flow activation at 0.53 GPM ensures burner engagement for small faucets
• Adjustable temperature settings reach up to 149 degrees F for sanitizing needs

Cons

• High 199,000 BTU rating may require upgrading existing gas supply lines to 3/4-inch
• Not recommended for high-altitude installations above 3,000 feet elevation
• Requires manual draining via the pressure relief valve during severe cold spells

10

MIZUDO MIZUDO Natural Gas Tankless Water Heater Indoor&Outdoor Convertible Installation

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  7.2
• Brand
  MIZUDO

Key specs2

Convertible Mounting

Designed for indoor placement out of the box, this unit can transition to an outdoor setup using an optional manufacturer conversion kit to avoid indoor venting.

Burner and Core Build

Stainless chamber and copper exchanger

Pros & cons43

Pros

• Convertible configuration supports indoor or outdoor setup with optional kit
• Integrated WiFi connectivity provides remote app tracking and maintenance alerts
• Gas modulation system maintains outlet water temperatures within 1 degree F
• Stainless steel combustion chamber pairs with a deoxidized copper heat exchanger

Cons

• Outdoor installation requires purchasing a separate conversion kit
• Flow rate tops out at 5.1 GPM, which limits large multi-bath peak usage
• High-altitude performance limits and warranty duration are unstated in listing

Last update on 2026-10-16 / Affiliate links / Images, Product Titles, and Product Highlights from Amazon Product Advertising API

Is a natural gas water heater cheaper to run than an electric model?

Yes, natural gas water heaters generally deliver lower monthly operating costs than standard electric tank units. For instance, non-condensing natural gas tankless heaters with a 0.82 Uniform Energy Factor (UEF) are listed to save up to 34% on energy costs compared to 50-gallon electric tank heaters. Advanced condensing gas units achieve a 0.93 UEF, which further drives down ongoing utility expenses. However, operating savings can be reduced if your home lacks an active gas supply line, as running new piping requires extra setup. If your utility layout favors electricity, checking the best electric tankless water heater for home use helps you evaluate whether your existing breaker panel can handle the load without a service upgrade.

Can a natural gas water heater keep up with two or three showers running at once?

Yes, high-output natural gas tankless water heaters easily handle simultaneous showers. A model with a 199,000 BTU heating input delivers up to 10.3 GPM, which supports continuous hot water across two to three bathrooms and kitchen faucets at the same time. For moderate demands, a 113,000 BTU unit providing up to 5 GPM can run two showers simultaneously at a stable 105°F based on a 65°F inlet water temperature. Smaller units rated at 95,000 BTU and 4.42 GPM are best suited for single-fixture demand or smaller homes where multiple showers rarely run together.

Do you need dedicated venting or gas line upgrades to install an indoor natural gas water heater?

Yes, indoor natural gas water heaters require direct venting to the outside to discharge combustion gases safely. Condensing indoor models utilize direct vent systems, while certain indoor designs feature blowers placed underneath to prevent smoke backflow. If running vent pipes through an exterior wall or roof is difficult, outdoor tankless models eliminate indoor venting entirely. For gas supply lines, you must verify that your line delivers sufficient volume for high-demand burners ranging from 95,000 BTU to 199,000 BTU, because undersized gas piping will limit heating performance.

How much does a high UEF rating reduce monthly energy bills?

A higher Uniform Energy Factor directly translates to lower utility consumption by converting more fuel into usable heat. Choosing a natural gas tankless model with a 0.82 UEF can save up to 34% on energy costs compared to a traditional 50-gallon electric storage tank. Upgrading to a condensing unit with a 0.93 UEF captures extra heat from combustion gases, lowering gas consumption even more. For large households using hot water throughout the day, this efficiency difference provides consistent monthly utility savings across 2026.

Does a natural gas water heater require an electrical connection to run?

Yes, indoor natural gas tankless water heaters require electricity to operate their electronic controls. While the natural gas line powers the burner, a standard 120-volt connection runs the digital display, internal monitoring sensors, electronic ignition, and motorized exhaust fans. Unlike whole-home electric tankless units that require substantial amperage and multiple heavy-duty circuit breakers, a gas unit draws minimal electric power from a regular wall outlet. You should verify your utility closet has an accessible 120-volt outlet before scheduling your installation.

How do natural gas tankless water heaters prevent cold water swings during use?

Modern natural gas tankless systems use advanced gas modulation to maintain water temperatures within ±1°F of your selected setting, with some models adjusting up to 149°F. These units eliminate the 30-minute preheating wait time common with standard water tanks, and models equipped with single-circulation technology reduce cold water wait times at the faucet. In addition, CSA-certified units feature protective controls for boil-dry, freeze, flame-out, overheat, timeout, and pipe blockage to keep water delivery safe and continuous.