Our readers keep the lights on and my morning glass full of iced black tea. As an Amazon Associate, I earn from qualifying purchases.13 Best 80 Gallon Gas Water Heater | Skip the Tank, Save Space

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This Rheem Prestige unit delivers a substantial 9.5 GPM flow rate, making it one of the few consumer-grade tankless heaters that can genuinely support three or more simultaneous showers plus appliances without noticeable temperature drop. The internal water and gas leak detection system adds a layer of safety that automatically shuts down the unit and displays an error code, which is rare even at this level.

At 77 pounds, the unit’s heft reflects the commercial-grade copper heat exchanger and robust burner assembly inside. Owners consistently report that it handles 50-minute showers and simultaneous washing machine cycles without ever running cold. The compact footprint, just 18.5 inches wide and 27.5 inches tall, frees up significant floor space compared to a traditional 80-gallon tank.

Some users have flagged that the packaging could be more protective, as units occasionally arrive with cosmetic damage. The condensation line can also freeze in single-digit temperatures if the unit is installed in an uninsulated crawlspace. Professional installation is strongly recommended to avoid error code issues during initial startup.

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The Rinnai RXP199iN represents the pinnacle of residential tankless engineering with its 11.1 GPM flow rate and 199,000 BTU output, capable of supplying up to seven fixtures at once. The built-in Smart-Circ recirculation pump learns your household’s usage patterns to deliver faster hot water to distant faucets while minimizing water waste and energy consumption.

This unit’s condensing design achieves a UEF of 0.98, meaning it converts 98% of its fuel into usable heat — vastly exceeding the efficiency of any traditional tank heater. The Smart Sense gas control automatically detects whether you’re using natural gas or propane, eliminating the need for conversion kits. Installation flexibility is unparalleled since it works both indoors and outdoors with the Versa Vent system.

Some owners note that the recirculation pump can be louder than expected, particularly in economy mode where it cycles more frequently. The Rinnai Central App compatibility requires the separately sold Controlr module, which is an added expense. Professional installation is non-negotiable to maintain the 15-year heat exchanger warranty.

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The RU199iN delivers 11 GPM of continuous hot water with a 199,000 BTU burner, making it a direct competitor to the flagship models at a more accessible price point. It includes Circ-Logic technology that pairs with an external recirculation pump, allowing scheduled or on-demand recirculation to reduce wait times at distant fixtures. This unit handles up to seven appliances simultaneously without pressure loss.

Weighing 74 pounds with a compact 9-inch depth, this condensing unit fits in tight utility spaces where larger tank systems cannot. Users report stable temperature output even with multiple showers and appliances running, with some noting that the hot water reaches second-floor bathrooms within one minute. The ENERGY STAR qualification and UEF of 0.105 reflect solid efficiency for a non-condensing unit.

A few buyers discovered missing union fittings upon delivery, though Rinnai customer service promptly sent replacements. The unit also lacks a built-in recirculation pump, so you must purchase and install one separately to get recirculation benefits. Amazon’s installation service may refuse tankless heater installations, so securing a local plumber ahead of time is wise.

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The CX199iN is built for the most demanding residential and light commercial applications, delivering 11.1 GPM with a thermal efficiency rating of 97%. Its heavy-duty construction includes a stainless steel heat exchanger designed to withstand continuous high-output operation that would stress standard residential units. The Smart Sense gas control automatically switches between natural gas and propane without manual conversion.

Owners upgrading from older tankless systems report dramatic efficiency gains, with one user noting a savings of 360 kWh in the first month compared to a previous heat pump hybrid unit. The quick flush system simplifies annual descaling maintenance, a critical factor for longevity in hard water areas. The Versa Vent system enables both indoor and outdoor installation with the appropriate vent cap.

The unit’s 15-inch depth is notably deeper than standard residential models, which may complicate retrofits into existing utility closets. The optional recirculation conversion kit adds cost if you want recirculation functionality. Some users found that the unit’s taller height required plumbing modifications during installation.

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The Rinnai RX199iN brings smart functionality to the forefront with its Bluetooth-enabled Smart Sense system that allows setup and troubleshooting through the Rinnai Central App. The unit delivers 11.1 GPM at 199,000 BTUs with a UEF of 0.98, placing it among the most efficient residential tankless heaters available. The Quick Flush feature simplifies maintenance by providing dedicated ports for system flushing.

This model’s Versa Vent technology gives you the freedom to install indoors or outdoors using the same unit, with the RX-OVC vent cap required for outdoor setups. Families of five report that the unit runs multiple showers, the dishwasher, and laundry simultaneously without any temperature or pressure fluctuations. The 15-year heat exchanger warranty provides long-term peace of mind.

WiFi control requires the separate Controlr module, which is not included and adds to the upfront cost. The 30.11-inch height may not fit in all utility spaces, particularly if your previous unit was shorter. Some users found that professional installation is particularly important because the unit’s sensitivity to gas line sizing can trigger error codes if undersized.

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The Takagi T-H3S-DV-N is a condensing unit that offers 8 GPM of continuous hot water with ultra-low NOx emissions, making it compliant with the strictest air quality regulations like SCAQMD Rule 1146.2. Its 22.5-inch height and 10.75-inch depth make it one of the most compact condensing units available, fitting into spaces where larger tankless heaters simply cannot go.

Owners with long-term experience report that previous-generation Takagi units ran reliably for over 16 years with only occasional motherboard replacements under warranty. The unit’s computerized safety features eliminate the pilot light, reducing standby gas consumption. Installation is straightforward for those with mechanical experience, typically taking 4-5 hours with a plumber.

Hard water areas require biannual descaling, which adds ongoing maintenance costs and effort. The unit is also incompatible with older metal venting systems, meaning a complete vent replacement may be necessary during installation. The 1/2-inch gas line found in many homes will need upgrading to 3/4-inch to meet the unit’s gas flow requirements.

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The ThermoMate RTC68iN achieves a 0.91 UEF through its dual heat exchange system that pairs a stainless steel condensing heat exchanger with an oxygen-free copper heat exchanger, capturing waste heat that traditional models simply exhaust outside. This design reduces annual hot water costs by approximately 17% compared to standard tankless units, making it a strong choice for efficiency-focused buyers.

With 163,000 BTUs and 9.38 GPM capacity, this unit can supply three simultaneous showers at 105°F when the inlet water is at 62°F. The intelligent water mixing valve technology maintains zero temperature fluctuation even during multi-shower use, which is a standout feature at this price point. The sealed combustion design keeps operational noise notably low.

As a condensing unit, this model produces mildly acidic condensate that requires a neutralizer kit to prevent pipe corrosion — an additional expense not included in the box. The 28.44-inch height and 23.7-inch depth require more wall space than some competitors. Some users found the unit’s 75,000 BTU version undersized for whole-home use, so the 163,000 BTU model is essential for large households.

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The A. O. Smith ATI-310CX3 stands apart with its proprietary X3 Scale Prevention Technology that uses an integrated filter to reduce mineral buildup, eliminating the need for annual descaling and isolation valves. This is a significant maintenance advantage in hard water regions where tankless heaters typically require yearly vinegar or citric acid flushes to maintain performance.

Delivering 8 GPM at 190,000 BTUs, this unit includes a propane conversion kit in the box, saving you the cost of a separate conversion. The commercial-grade copper heat exchanger provides 25 times better heat transfer compared to steel, contributing to its 0.81 UEF rating. The 20.5-inch height is shorter than most competing units, fitting more easily under low ceilings.

At 51 pounds, this unit is lighter than many competitors, but the lighter weight also reflects a less robust overall construction. The 15-year heat exchanger warranty is competitive, but the comprehensive warranty is just 5 years. Some users noted that professional installation took under half a day, but finding an installer familiar with tankless units in remote areas can be challenging.

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The Westinghouse HW180A0G-NG brings smart home integration to the tankless market with full WiFi app control that lets you adjust water temperature and monitor operating status from anywhere. Its advanced self-modulating technology maintains output temperature within ±1°F, effectively eliminating the cold bursts that plague older tankless designs during simultaneous fixture use.

With 180,000 BTUs and 7.9 GPM, this unit comfortably supports 3-5 fixtures simultaneously, making it suitable for medium to large homes. The CSA certification and freeze protection ensure reliable operation through winter conditions, while the copper heat exchanger provides long-term durability. The compact 17.1-inch width and 26.2-inch height allow for flexible wall mounting.

Some users report a 1-2 minute delay before hot water reaches distant fixtures, which is normal for non-recirculating tankless systems but worth noting if instant hot water is a priority. Finding a contractor willing to install an unfamiliar brand can take extra effort. The maximum temperature of 165°F is adequate but lower than some competing units that reach 194°F.

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Designed specifically for outdoor propane installation, the Westinghouse HS180A0G-LP delivers 8.1 GPM at 180,000 BTUs without taking up any indoor space. The included indoor remote control panel lets you adjust temperature settings from inside your home, providing convenient access without having to go outside. The variable-speed combustion fan and integrated freeze protection ensure reliable year-round operation in changing weather.

This unit’s non-condensing design simplifies installation by eliminating the need for a condensate drain line, which is particularly advantageous for outdoor setups where routing a drain would be difficult. The ±1°F temperature stability ensures consistent shower temperatures even when multiple fixtures are in use. The compact wall-mounted design saves valuable indoor space while delivering whole-home hot water performance.

Outdoor installation requires the unit to be protected from direct rain and snow, typically under a roof overhang or in a sheltered location. The maximum temperature of 165°F is lower than some indoor units, which may be a consideration if you require very hot water for specific applications. In temperatures below 5°F, the system must be fully drained to prevent freeze damage if not in use.

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The Rheem RTG-70DVLN-3 is a non-condensing unit that delivers 7 GPM at 160,000 BTUs, making it a solid choice for 2-3 bathroom homes where moderate hot water demand is the norm. The Hot-Start programming prevents cold water bursts during back-to-back showers, a thoughtful feature that improves comfort during busy morning routines. The 15-year heat exchanger warranty provides strong long-term protection.

This unit’s non-condensing design means simpler installation since there is no condensate drain to route, but it also requires Category III stainless steel venting that can be costly. The compact metal cabinet, measuring 13.5 inches wide by 24.2 inches tall, fits easily into standard utility spaces. Owners report that professional installation typically runs around , depending on venting requirements.

The 7 GPM flow rate is sufficient for two simultaneous showers plus one appliance, but larger homes with three or more bathrooms may find it limiting during peak demand. Some users note that the unit takes longer than expected to deliver hot water to distant fixtures, a common characteristic of non-recirculating tankless systems. The special venting pipe required is not included and adds significant installation cost.

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The MIZUDO tankless water heater offers an impressive feature set at a budget-friendly price point, including WiFi and smartphone app control for remote temperature monitoring and adjustment. Its CSA certification confirms compliance with rigorous safety standards, and the advanced sealed combustion system draws external air for operation, preserving indoor air quality. The unit delivers 7.9 GPM at 180,000 BTUs, supporting 3-5 usage points.

The oxygen-free copper heat exchanger provides superior thermal conductivity and durability, while the 5-year heat exchanger warranty and 2-year comprehensive warranty offer reasonable protection. At just 39.55 pounds, this unit is significantly lighter than competitors, making it easier to handle during installation. The compact 25-inch height and 16.3-inch width require 50% less space than a traditional tank heater.

Some customers reported that the casing could be reinforced, suggesting the exterior build quality is not as robust as premium brands. The stainless steel double-wall flue vent is sold separately, adding to the total installation cost. The minimum activation flow of 0.53 GPM means very low-flow fixtures may not trigger the heater consistently.

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The Ranein tankless water heater delivers 8.5 GPM with 190,000 BTUs, offering one of the best flow-to-BTU ratios in the budget segment. The blower fan is placed underneath the unit for enhanced safety and smoke backflow prevention, and it automatically adjusts speed based on external wind pressure and water temperature to ensure complete combustion. This design extends the unit’s service life while keeping noise levels low.

Owners report significant energy savings, with one household of 8 people noting a monthly reduction in gas bills after replacing a 40-gallon tank. The compact dimensions of 24.25 inches high by 15.08 inches wide take up minimal wall space compared to traditional tank systems. The standard 3/4-inch NPT water fittings simplify installation for DIYers with basic plumbing experience.

The 2-year warranty is shorter than most competitors, and some users experienced early component failures that required customer service intervention. This unit is not recommended for installations above 2,000 feet elevation due to combustion performance limitations. Propane users should verify the conversion kit’s availability, as the unit is primarily designed for natural gas.