Our readers keep the lights on and my morning glass full of iced black tea. As an Amazon Associate, I earn from qualifying purchases.11 Best 50 Gallon Natural Gas Water Heater | Endless Showers

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The Rinnai CX199iN is a commercial-grade condensing tankless water heater that operates at 97% thermal efficiency, making it one of the most energy-efficient natural gas units in this lineup. Its 199,000 BTU burner and 11.1 GPM flow rate are enough to supply 7 fixtures simultaneously—two showers, a dishwasher, a washing machine, and two faucets without a noticeable temperature drop.

This unit uses the Smart Sense gas control system, which automatically adjusts between natural gas and propane with no conversion kit required. The condensing design captures waste heat from exhaust gases, contributing to the exceptional efficiency rating. Professional installation is strongly recommended due to the specific venting requirements for condensing models.

Users consistently praise its quiet operation and the fact that a family of 8 can run multiple appliances without running out of hot water. The “Quick Flush” feature simplifies the annual descaling process, and the Rinnai Central App provides Bluetooth setup and monitoring. The CX199iN represents the top end of residential performance and is ideal for large households with high simultaneous demand.

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The Rinnai RX199iN is the residential sibling of the CX199iN, sharing the same 199,000 BTU burner and 11.1 GPM capacity, but designed specifically for home use. It achieves a UEF of 0.98, which is near the theoretical maximum for gas water heaters, translating to almost all of the gas energy being converted into usable heat with minimal waste. This efficiency leads to substantially lower monthly gas bills compared to any 50-gallon tank model.

The RX199iN is designed for installation both indoors and outdoors using the Versa Vent system, which simplifies venting requirements. The RX-OVC vent cap is required for outdoor installation. It also includes the Smart Sense gas control, allowing the same unit to run on natural gas or propane without a mechanical conversion kit, giving homeowners fuel flexibility.

Users report that the unit is very quiet in operation and that even with a family of five running multiple showers concurrently, hot water never runs out. The compact suitcase-sized footprint frees up significant floor space. One caveat is that water at distant faucets can take 20-30 seconds to arrive hot, which is common across all tankless systems and can be mitigated with a recirculation pump.

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The A. O. Smith ATI-310CX3 distinguishes itself with X3 Scale Prevention Technology, which uses an integrated filter and fluid dynamics to reduce mineral scale buildup inside the heat exchanger. This eliminates the need for annual descaling and isolation valves, directly reducing maintenance overhead. The unit delivers 8.0 GPM at 190,000 BTU, making it suitable for 2-3 bathroom homes with typical simultaneous usage.

Its commercial-grade copper heat exchanger provides 25 times better heat transfer than steel, enabling rapid temperature recovery and tight stability. The unit is non-condensing and uses a concentric vent system (APNC35, sold separately), which simplifies venting through a single wall penetration. A propane conversion kit is included in the box, saving you an extra purchase if you need to switch fuel types.

Homeowners appreciate the unit’s quiet operation and the fact that a professional installer described it as “a nice unit” with straightforward installation. The 15-year limited warranty on the heat exchanger and the built-in diagnostics display add long-term peace of mind. The UEF of 0.81 is solid but not class-leading; the trade-off is lower maintenance requirements compared to higher-efficiency condensing models.

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The Rheem RTG-84XLN-3 is an outdoor-specific tankless water heater that delivers 8.4 GPM from a 180,000 BTU burner, making it one of the highest-flow outdoor units in this comparison. Because it installs outside, it requires zero indoor venting—no PVC pipes through the roof or side walls. This dramatically reduces installation complexity and cost, as long as local climate conditions allow for an outdoor unit.

The unit is non-condensing and uses a durable metal cabinet with integrated freeze protection down to -30°F, which makes it viable even in colder climates. Hot-start programming actively prevents cold water sandwiches during back-to-back showers, a common complaint with older tankless designs. The compact dimensions (13.5″ x 20.75″) allow it to be wall-mounted in a relatively small footprint.

User feedback highlights the ease of installation compared to indoor models, with several noting that a qualified plumber can complete the job in half a day. The unit runs reliably and delivers continuous hot water once the flow has been established for a few seconds. Some users note the typical tankless delay of 10-15 seconds for hot water to arrive at the tap, but the flow rate is more than sufficient for 2-3 bathrooms running simultaneously.

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The Westinghouse HW180A0G-NG is a smart-enabled indoor tankless water heater that delivers 7.9 GPM from a 180,000 BTU burner, comfortably supporting 3-5 fixtures. Its standout feature is the WiFi app control, which allows you to adjust water temperature, monitor operating status, and set schedules from a smartphone. This is particularly useful for preheating the system before your typical shower time.

Advanced self-modulating technology maintains output temperature within ±1°F regardless of fluctuations in incoming water temperature or flow rate. This means no cold surprises when someone flushes a toilet or opens a kitchen faucet while you are showering. The unit is non-condensing and designed for indoor installation with standard 3/4″ NPT water connections.

Installation feedback is overwhelmingly positive, with multiple users describing the process as “very easy” thanks to clear step-by-step instructions and well-labeled components. The unit also features freeze protection and a variable-speed combustion fan that adjusts to venting conditions. The warranty is comprehensive, though exact terms should be verified at purchase.

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The Rheem RTG-70DVLN-3 is a proven non-condensing indoor unit that produces 7.0 GPM from a 160,000 BTU burner, making it a good fit for 2-3 bathroom homes where simultaneous demand is moderate. It is known for reliable operation and straightforward installation by a qualified plumber. The unit includes Hot-Start programming to minimize the cold water sandwich effect during back-to-back showers.

One distinctive aspect of this model is the specific venting requirement: it needs Rheem’s special venting pipe system, which can be more expensive than standard PVC but ensures proper exhaust handling for the non-condensing combustion process. The unit is CSA certified and comes with a strong warranty package: 15 years on the heat exchanger, 5 years on parts, and 1 year on labor.

Users highlight the endless hot water supply and the significant reduction in gas bills compared to their previous tank water heaters. The compact cabinet (13.5″ x 24.2″) frees up floor space in basements or utility rooms. The primary downside is that the specialized venting can add -400 to the total installation cost if you are replacing an existing tankless unit with different venting standards.

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The Noritz NR50ODNG is a simple, rugged outdoor tankless water heater that has been a staple on job sites and homes for years. With a 5.0 GPM flow rate and 120,000 BTU, it is not the highest-flow unit in this list, but it is extremely reliable for small to medium households with 1-2 simultaneous fixture demands. Many professional plumbers specifically recommend Noritz for easy parts availability and straightforward service.

Because it is designed for outdoor installation, there is no need for indoor venting—the unit mounts on an exterior wall and uses the ambient outdoor air for combustion. The build quality is what you expect from a Japanese manufacturer with decades of tankless experience: solid copper heat exchanger, durable cabinet, and minimal electronic complexity. Some users note the minimum temperature setting is 115°F, which may be warmer than desired in warmer climates where lower tap temperatures are preferred.

Long-term user reports are very strong, with multiple reviews describing flawless operation after 2+ years. The unit reportedly cuts gas bills significantly—one user reports their gas bill dropping from to per month after switching from a tank heater. A remote control is available separately, and a scale inhibitor cartridge is recommended for hard water areas.

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The FOGATTI Instagas Comfort 120S is an outdoor-only tankless water heater that offers 5.1 GPM from a 120,000 BTU burner, designed specifically for medium-sized families. Its compact form factor (15.5″ x 23.9″) takes up about a third of the space of a traditional tank heater, and the outdoor installation eliminates the need for any venting through the house.

Advanced water servo technology and temperature sensors allow the unit to maintain output temperature within ±1°F by precisely regulating both gas and water flow. The unit operates on a standard 120V AC electrical connection and works with low water pressures down to 15 PSI, making it suitable for rural properties or well-water systems. A remote control panel is included for indoor operation adjustments.

Users report that the unit provides instant hot water and frees up significant garage or basement space. The installation instructions could be clearer, but the manufacturer’s phone support is helpful. It is important to note that the unit has active freeze protection, but if ambient temperatures drop below 5°F for extended periods, the water must be drained to prevent freeze damage. This unit is best for mild to moderate climates.

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The APUS AP-AWH-Q20NG is a feature-rich indoor tankless water heater that delivers 6.8 GPM from a 140,000 BTU burner, with an integrated booster pump that increases water flow by up to 130%. This pump allows the unit to effectively handle 2 showers and 2 sinks simultaneously without noticeable temperature fluctuations. The booster is a rare and valuable addition in this price tier.

Its most distinctive feature is the Zero Cold Water single-circulation technology, which keeps a small amount of water recirculating in the pipes to virtually eliminate the cold water wait time. This is usually achieved only with an external recirculation pump, so having it built-in is a significant convenience. The unit also includes WiFi control via the Tuya app, a Smart Season comfort mode that auto-adjusts based on incoming water temperature, and a bottom turbo fan that makes it 30% quieter than standard tankless units.

Users appreciate the instant hot water delivery and the robust build quality, with the copper heat exchanger and stainless steel combustion chamber. The unit is compatible with standard 1/2″ NPT connections and is compact enough to fit in a cabinet when proper ventilation is provided. Some users have reported ignition issues, but the majority experience reliable performance. The included vent pipe and assembly kit make the initial installation more straightforward than many competitors.

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The MIZUDO GEN 3 is a versatile tankless water heater that can be installed either indoors or outdoors using a purchase-required conversion kit, offering flexibility that few competitors in this price range can match. It delivers 5.1 GPM from a 120,000 BTU burner, making it best suited for small to medium households with 1-2 simultaneous fixture needs, such as a shower and a kitchen faucet.

Smart WiFi and app control allow you to adjust temperature settings, monitor energy usage, and receive maintenance notifications from a smartphone. The unit features a phosphorous-deoxidized copper heat exchanger and a stainless steel combustion chamber for long-term durability. It is CSA certified and includes multiple safety mechanisms: freeze protection, dry burn prevention, flame failure detection, and exhaust blockage protection.

User reports highlight the extremely easy installation process, with several DIYers completing the swap from a tank heater in under 3 hours. The unit is surprisingly light and compact, making wall mounting simple. The app works well for remote adjustments, and the unit is notably quiet during operation. One drawback is that the recirculation mode is not built-in, so a separate recirculation system is needed if you want instant hot water at distant taps.

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The GASLAND Gasmart E CE528NG is a compact indoor tankless water heater that offers 5.8 GPM from a 150,000 BTU burner, making it a strong entry-level option for small to medium households. At this spec level, the unit can support a shower and a kitchen faucet simultaneously, or a shower and a washing machine, but may struggle with three simultaneous high-flow fixtures.

Its UEF of 0.8 makes it 34% more energy efficient than a standard 50-gallon tank water heater (which typically has a UEF of 0.6). The unit is CSA certified and features multiple safety systems including overheat protection, flame-out protection, and freeze protection. The compact size of 14.25″ x 24.69″ allows it to be mounted in small spaces like closets or laundry rooms.

Users generally report good value for the price, with many noting the customer support team is responsive and helpful. The copper pipes come with foam insulation, and the front panel displays water temperature. Some users note that the assembly is harder than expected and that the inlet/outlet spacing is uneven, which complicates plumbing connections. A significant minority reported reliability issues, with one unit failing after about 4 months of use, so be prepared for the possibility of warranty replacement. This unit is best for those on a tight budget who are comfortable with potential service needs.