13 Best 75 Gallon Gas Water Heater | Endless Flow, Zero Wait

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The RXP199iN is Rinnai’s most advanced residential unit, combining a condensing design that hits a UEF of 0.98 with a fully integrated Smart-Circ recirculation pump. This eliminates the need for a separate recirculation loop and external pump, drastically simplifying installation for homes that want instant hot water at every tap. At 11.1 GPM and 199,000 BTU, this unit can supply up to 7 fixtures simultaneously without measurable temperature drop, making it ideal for 5+ person households.

Real owners report replacing 40- to 50-gallon tank units and experiencing genuinely endless hot water for simultaneous showers, dishwasher, and laundry cycles. The unit is very quiet in operation — several owners noted they barely hear it running when mounted in a garage or utility room. The Smart-Circ pump adapts to usage patterns over time to minimize energy waste, though some users wish the pump frequency had more granular control beyond the economy/comfort toggle.

The Versa Vent system allows both indoor and outdoor installation, and the Smart Sense gas control automatically detects and adjusts for natural gas or propane without a conversion kit. Professional installation is strongly recommended given the 199k BTU input and the need for proper gas line sizing, but experienced DIY owners report a straightforward install with standard PVC venting. The 58-pound weight requires a second person for wall mounting.

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The RX199iN sits just below the RXP in Rinnai’s lineup, offering the same 11.1 GPM flow capacity and 199,000 BTU output but without the built-in recirculation pump. This makes it a smarter choice for homes that already have a dedicated recirculation line or are willing to add an external pump. The condensing design delivers a UEF of 0.98, qualifying for many utility rebate programs and slashing standby losses compared to non-condensing units.

Owners with families of 5 or more report dramatic improvements in daily comfort, with multiple simultaneous showers producing zero pressure or temperature fluctuations. Several reviewers noted the unit is quieter than their previous tank-style heater and noticeably more compact — the 30-inch height fits neatly into tight basement or closet spaces. The Quick Flush feature makes annual descaling significantly less tedious than units requiring isolation valve kits.

Installation is versatile: the RX199iN can be mounted indoors or outdoors using the Versa Vent system, and the Smart Sense gas control automatically adjusts for propane or natural gas. One common feedback point is the delay in hot water reaching distant faucets — an external recirculation pump solves this, but adds cost and complexity. Professional installation remains recommended due to the gas line sizing requirements for this BTU level.

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The CX199iN is Rinnai’s commercial-tier offering repurposed for demanding residential use, boasting a 97% thermal efficiency rating and a flow rate of 11.1 GPM. It shares the same core 199,000 BTU burner platform as the RX series but is built with more robust internal components designed for higher duty cycles — ideal for multi-generational homes, properties with in-law suites, or homes that frequently host guests. The Smart Sense gas control automatically handles fuel type detection.

Owners replacing aging tank heaters report staggering energy savings: one reviewer documented a drop of 360 kWh in the first month after switching from electric heat pump hybrids. Another owner running a high-altitude mountain campground shower house found the CX199iN performed reliably where lesser units struggled. The unit supports an optional recirculation conversion kit for homes wanting instant hot water, though the kit must be purchased separately.

The physical dimensions are identical to the RX199iN (18.5”W x 30.11”H) but the weight is slightly higher due to the reinforced heat exchanger. Installation requires 3/4” gas line and careful vent planning. Several owners noted the unit is taller than their previous 18-year-old Rinnai, requiring minor plumbing relocation. The unit qualifies as ultra-low NOx for California and other strict emissions regions.

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Westinghouse brings genuine smart home integration to the tankless space with this 10.3 GPM indoor unit. The dedicated smartphone app and voice control via Alexa or Google Assistant let you adjust temperature, monitor burner status, and receive fault alerts from anywhere. At 199,000 BTU, it supplies 4+ bathrooms with enough headroom for simultaneous laundry and dishwasher use.

The 1:20 turndown ratio is particularly impressive — it allows the burner to modulate down to very low flow rates without shutting off, effectively eliminating the cold water sandwich problem that plagues units with narrower modulation ranges. The phosphorus-deoxidized copper heat exchanger resists corrosion and provides fast heat transfer. Owners consistently praise the ±1°F temperature stability, with one reviewer noting they set it at 116°F and never touch the cold water handle.

Freeze protection is rated down to -13°F, making this unit viable for cold climate basements. The 6-stage combustion system optimizes gas usage based on real-time demand. However, some users report difficulty finding contractors familiar with the brand, and the proprietary WiFi app occasionally loses connection. The unit is heavier than some competitors at roughly 50 pounds.

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This Rheem RTGH model fills a sweet spot for larger homes that don’t quite need the 11 GPM of the premium Rinnai units but still require high simultaneous flow. With a 9.5 GPM capacity and 199,900 BTU input, it comfortably handles 3 bathrooms plus kitchen and laundry simultaneously. The 0.4 GPM minimum activation flow is lower than many competitors, meaning it will fire even at a trickle — helpful for handwashing scenarios.

Owners who DIY-installed this unit praise it as their second Rheem tankless, citing straightforward installation with Propress fittings and gas line hookups. The default 120°F temperature setting is fine for most homes, and the range extends from 100°F to 140°F. The compact 17.7” width and 23.7” height allow fitting into tighter spaces than the taller Rinnai condensing units.

Warranty coverage is solid: 15 years on the heat exchanger, 5 years on parts, and 1 year on labor. The unit is non-condensing, so it requires Category III stainless steel venting rather than cheaper PVC. Owners recommend annual filter cleaning and flushing every few years to maintain performance. The 59.9-pound weight makes it one of the heavier units in its class — a two-person mount is essential.

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A. O. Smith tackles the single biggest maintenance headache of tankless water heaters — scale buildup — with its X3 Scale Prevention Technology. This built-in system prevents mineral scale from accumulating on the heat exchanger, eliminating the need for annual descaling and isolation valve kits. For homes in hard water regions, this feature alone can save hundreds of dollars in maintenance costs and extend the unit’s lifespan significantly.

The unit delivers 8.0 GPM at 190,000 BTU, suitable for 3-4 bathroom homes. The commercial-grade copper heat exchanger provides 25x better heat transfer than steel, and the Uniform Energy Factor of .81 keeps operating costs reasonable. The concentric vent system (APNC35) supports both vertical and horizontal termination, and a propane conversion kit is included in the box — unusual at this tier. Owners consistently describe the unit as quiet, compact, and capable of maintaining a rock-steady 115°F even with multiple fixtures running.

Installation requires professional help according to nearly every owner, but experienced DIY users report completing the job in 2-16 hours depending on gas line and vent complexity. Some owners encountered issues with shower balancing valves causing the unit to momentarily cut off — solved by installing cold water restrictors. The safety suite includes exhaust temperature sensors, overheat cut-off fuses, and an air-fuel ratio sensor.

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Westinghouse designed this outdoor-rated propane unit for homes that want simple installation without indoor venting requirements. At 8.1 GPM and 180,000 BTU, it supports 3-5 fixtures simultaneously — enough for a family running two showers and a dishwasher. The self-modulating technology adjusts gas and water flow in real-time to maintain outlet temperature within ±1°F, preventing the cold bursts that plague less precise units.

The included indoor remote control panel is a standout feature — a wired LED display that lets you set temperature and view operating status from inside the house without walking outside. Owners praise the easy installation, with several reporting they completed the wall mount and gas hookup in under an hour. The CSA certification and integrated freeze protection make it suitable for year-round outdoor operation in moderate climates.

The compact 17.1” x 26.8” footprint is smaller than many indoor units, and the grey metallic cabinet resists weathering. Compatibility with standard 3/4” NPT plumbing connections means no adapter fittings are needed for most retrofit jobs. However, the unit requires a 120V AC power source even for outdoor installation, which may require running an outdoor-rated electrical line. Some owners note occasional delay in hot water reaching distant fixtures during first use.

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The RE140iP is a workhorse non-condensing propane unit for homes that don’t want the complexity or cost of condensing technology. With 140,000 BTU and 5.3 GPM, it’s sized for homes with up to 5 fixtures — ideal for a 2-3 bathroom house that doesn’t run everything at once. The compact suitcase-sized body (14.05”W x 27.28”H) fits into standard cabinet spaces or small utility closets.

Owners replacing older tankless units report flawless operation, with one Airbnb host noting that switching from a Camplux to the RE140iP eliminated all guest complaints about heater ignition failure. The LED screen provides service reminders and error codes that simplify troubleshooting. The smart design layout improves serviceability compared to earlier Rinnai generations, and the 15-year heat exchanger warranty backs the build quality.

Installation requires professional recommendation by Rinnai, and the unit needs Category III venting due to its non-condensing nature. Some owners experienced intermittent short cold bursts followed by very hot water — a symptom of undersized gas supply or improper venting rather than the unit itself. The Controlr WiFi module is sold separately if you want remote monitoring capability.

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The RX130iN is the smaller sibling in Rinnai’s condensing lineup, offering 7.1 GPM and 130,000 BTU — a perfect fit for 3-4 bathroom homes that don’t need the massive flow of the RX199. The condensing design achieves a UEF of .97, allowing it to vent with inexpensive Schedule 40 PVC rather than costly stainless steel. The Smart Sense gas control automatically detects natural gas or propane, eliminating conversion kit requirements.

Owners in cold alpine climates report excellent reliability even at 10°F, with the unit handling two showers and a dishwasher simultaneously. The compact 19” x 31” dimensions are manageable for most basements and closets. Several DIY owners converted the unit to propane through the onboard settings menu without any hardware changes — one of the easiest fuel-type transitions on the market.

The Quick Flush feature simplifies annual descaling, and the Versa Vent system allows both indoor and outdoor installation with the proper vent cap. However, the unit does not include flush/diverter valves, a pressure release valve, or mounting brackets in the box — add roughly for these essentials. Some owners note the heating response is slightly slower than their previous tankless, estimating about 50% longer to reach full temperature from a cold start.

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The RTG-70XLN-3 is Rheem’s outdoor natural gas tankless offering, delivering 7.0 GPM at 160,000 BTU for 2-3 bathroom homes. Outdoor installation eliminates the need for indoor venting, saving hundreds in vent materials and labor. The hot-start programming prevents the cold water sandwich effect during back-to-back showers — a feature that matters more than most buyers realize until they experience it.

Owners praise the quick installation: one report shows a 40-minute mount and gas hookup with water flowing at 120°F within 10 seconds. The unit handles simultaneous water usage across 3 bathrooms with no noticeable pressure loss. The durable metal cabinet is weather-resistant, and the 39.3-pound weight makes it one of the lighter outdoor units — manageable for a single person to mount with a helper for alignment.

Customer service is a recurring weak point in owner reviews. Several users reported significant delays in warranty processing, and one owner received a defective unit with a non-functional electrical system that took weeks to resolve. While the unit itself performs well for most installations, having a qualified local plumber who can service Rheem products is important before purchase.

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The RTG-70DVLN-3 is the indoor counterpart to Rheem’s 7.0 GPM tankless line, designed specifically for indoor natural gas installations. It shares the same 160,000 BTU burner and 7.0 GPM capacity as the outdoor XLN model but includes the necessary venting adapters for indoor Category III venting. The slightly taller profile (24.2”H vs 20.75”H) accommodates the internal vent connector, and the weight increases to 46.5 pounds.

Owner experiences are positive overall, with many praising the endless hot water supply for a family of 4. The hot-start programming works well for back-to-back showers. The unit includes altitude adjustment settings, which one owner in a mountain home reported as crucial for proper combustion at elevation. Several reviewers noted the compact nature saved significant space compared to their old 50-gallon tank.

Installation requires Category III stainless steel venting, which some owners were surprised to learn after purchase — the vent pipe alone can cost -300 depending on run length. One owner mentioned the unit takes a noticeably long time to deliver hot water to distant faucets, which is a function of pipe length from the heater rather than the unit itself. The 15-year heat exchanger warranty provides good long-term protection.

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This is the liquid propane version of Rheem’s outdoor 7.0 GPM tankless heater, rated at 180,000 BTU — 20,000 BTU higher than the natural gas version to compensate for propane’s lower energy density per cubic foot. It’s designed for homes without natural gas access that rely on propane tanks, and the outdoor rating means no venting through the roof is needed.

Owners running on 23-gallon propane tanks report excellent results: one reviewer with a 130°F set point gets sufficient hot water for the whole household, with the compact unit mounted cleanly on an exterior wall. The unit has been tested successfully at high altitude for mountain campground applications, handling a 4-stall shower house without complaints. The hot-start programming prevents the cold water sandwich that plagues older tankless technology.

A critical warning from owners: the freeze protection is rated only to 30°F. One owner experienced an internal water leak when temperatures dropped to 20°F, and Rheem denied the warranty claim because the damage fell outside the specified freeze protection range. If you live in a region where temperatures regularly drop below freezing, this unit requires either a heated enclosure or winterization/drain-down procedures. Do not rely on the internal freeze protection alone in cold climates.

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The Noritz NR50ODNG is a compact entry-level outdoor unit suited for 1-2 bathroom homes or apartments. With 5.0 GPM and 120,000 BTU, it’s significantly less powerful than the other units in this list, but that also means it costs less and requires smaller gas lines. At 33 pounds, it’s the lightest unit reviewed here and one of the easiest to mount.

Owners praising this unit have had it running flawlessly for over 2 years, with one reviewer reporting their gas bill dropped from to -15 per month after replacing an electric tank. The quick response time delivers hot water within about 1 minute to the faucet. The unit is recommended by multiple plumbers for its reliability and parts availability at local supply houses.

A notable limitation: the minimum temperature setting is 115°F, which is hotter than some prefer for showering. The remote control (sold separately) can only adjust between 115-120°F after the initial 140°F setup. Some owners in hotter climates note that summer showers require a sink hot water trickle to keep the heater’s burner active — otherwise the flow rate drops low enough that the unit shuts off. Scale inhibitor is recommended for preventing mineral buildup.