Reader support keeps this site open, opinionated, and happily independent. As an Amazon Associate, I earn from qualifying purchases.11 Best 80 Gallon Water Heater | Why Big Tanks Fall Short

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The Rinnai RXP160iN is a condensing tankless water heater that installs indoors or outdoors and runs on natural gas or propane without conversion. Its UEF of 0.97 places it among the most efficient residential units available, and the built-in Smart-Circ recirculation pump learns your usage patterns to deliver hot water almost instantly to the farthest faucet.

With 9.0 GPM flow and 160,000 BTU input, this unit handles up to six fixtures at once — enough for a busy family with multiple bathrooms running simultaneously. The condensing design captures exhaust heat for extra efficiency but requires a PVC vent and a condensate drain line. Owners consistently praise the immediate hot water at regularly used faucets and note that gas bills remain comparable to or lower than older tank systems.

The biggest trade-off is complexity. The integrated recirculation pump cycles periodically to maintain warm water in the loop, which some users find causes a faint mechanical hum through the plumbing. The optional wifi module is sold separately and carries a premium price. Professional installation is strongly recommended, though several buyers successfully paired a delivered unit with a local plumber for roughly half the cost of a dealer quote.

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The A. O. Smith ProLine XE ATI-310CX3 stands out for its X3 Scale Prevention Technology, which uses a built-in filter cartridge to reduce mineral buildup without annual descaling or isolation valves. This is a game-changer for homes with hard water, where traditional tankless units require regular vinegar flushing to maintain flow rates.

Rated at 8.0 GPM with 190,000 BTU, this indoor non-condensing unit includes a propane conversion kit out of the box. The commercial-grade phosphorous-deoxidized copper heat exchanger delivers significantly better heat transfer than stainless steel alternatives. Owners report consistent 115°F output even with multiple fixtures active, and the unit operates quietly enough that it’s barely noticeable in an adjacent room.

The unit requires a 3/4-inch gas line and concentric venting (sold separately). Professional installation is recommended to ensure proper gas sizing and vent termination. The 15-year limited heat exchanger warranty adds long-term confidence, though a few users note the stainless steel outer cabinet shows fingerprints readily.

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The MIZUDO 199K BTU unit delivers the highest flow rate in this comparison at 10.3 GPM, making it the most capable option for very large homes with five to seven simultaneous fixtures. With 199,000 BTU input and a 6-stage gas modulation system, it maintains water temperature within ±1°F even when demand fluctuates.

Smart WiFi connectivity is built in — no extra module needed. You can adjust temperature, set schedules, and receive maintenance alerts from the dedicated mobile app. The sealed direct vent system draws combustion air from outside, preserving indoor air quality, though the vent kit must be purchased separately.

Owners report straightforward installation with standard 3/4-inch NPT connections, though the gas fitting may require an adapter if your existing line is 1/2-inch. The unit handles cold groundwater well in winter climates. A few users note that the app interface takes some getting used to, but once configured, it offers reliable remote control of the entire system.

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The Rheem RTG-84XLN-3 is an outdoor non-condensing tankless water heater running on natural gas with 8.4 GPM and 180,000 BTU. It’s sized for 2–3 bathroom homes and supports concurrent showers and laundry without noticeable pressure drops. Hot-start programming prevents cold water bursts between back-to-back showers.

Outdoor installation eliminates venting costs and saves interior space — it mounts directly to an exterior wall with a durable metal cabinet rated for weather exposure. The compact 13.5 x 20.75-inch footprint is smaller than many competitor units. Owners consistently report easy installation and reliable performance, with several mentioning that replacement of an older Rheem unit required minimal rework thanks to consistent mounting patterns.

The unit is not smart-home compatible, and the maximum output temperature is capped at 140°F. A few users note the slight delay typical of all tankless systems before hot water reaches distant faucets. Overall, this model offers a strong balance of flow rate and price for homes where outdoor mounting and natural gas are available.

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The Rheem RTG-84XLP-3 is the liquid propane counterpart to the RTG-84XLN-3, delivering identical 8.4 GPM and 180,000 BTU performance for homes using propane tanks rather than natural gas service. It’s designed for outdoor wall mounting and includes the same hot-start programming for comfortable consecutive showers.

Owners with propane setups report this unit handles cold groundwater in winter without struggling, maintaining consistent output temperatures. The 39-pound weight makes it manageable for a two-person installation. Several long-term users note the unit replaced an earlier Rheem that ran reliably for 11 years, indicating strong design continuity.

Some buyers have experienced persistent error code 11 issues that reset temporarily but return. Rheem customer support response on these cases has been mixed — some received replacement parts, others were directed to local service. Given this variability, confirming local warranty service availability before purchase is prudent for propane users.

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The Rheem RTG-70XLP-3 is a 7.0 GPM, 160,000 BTU outdoor propane unit suited for 2–3 bathroom homes with moderate simultaneous demand. It’s a step down in flow from the 84-series but still capable of handling a shower and dishwasher concurrently without a noticeable drop.

Owners using 23-gallon propane tanks report filling roughly every two months for daily family use, with operating costs significantly lower than electric resistance tanks. The outdoor cabinet holds up well in rain and snow, and the unit’s compact dimensions make it easy to mount in tight exterior spaces.

The 7.0 GPM flow is adequate for most families but may struggle if you have a large soaking tub or run three showers plus appliances at once. A few users experienced freeze-related failures when temperatures dropped below 20°F, and Rheem’s warranty explicitly excludes freeze damage below 30°F. If you live in a region with hard freezes, consider adding a freeze protection valve or choosing a unit with a lower minimum operating temperature.

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The Rheem RTG-70DVLN-3 is the indoor natural gas version of the 7.0 GPM platform, designed for 2–3 bathroom homes. It operates at 160,000 BTU with a non-condensing design that requires standard Category III stainless steel venting (sold separately).

Owners consistently describe this as a reliable replacement unit that delivers endless hot water for family use. The compact metal cabinet mounts easily on a wall, freeing up floor space previously occupied by a storage tank. Several buyers noted that replacing an older tankless Rheem required purchasing new venting components because the vent standards changed — factor this into your budget if upgrading from an older model.

The unit takes slightly longer than tank-type heaters to deliver hot water to distant bathrooms, a physics limitation of all tankless systems. Rheem backs the heat exchanger with a 15-year warranty. Some users recommend adding a recirculation loop if you want hot water at taps within seconds rather than minutes.

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The Westinghouse Smart Tankless Water Heater brings app-based temperature control to the tankless category without requiring a separate module. At 7.9 GPM and 180,000 BTU, it supports 3–5 fixtures and uses self-modulating technology to maintain water temperature within ±1°F.

Owners appreciate being able to adjust the water temperature from their phone, which is particularly useful for families who want different temperatures for baths versus daily showers. The unit’s freeze protection and variable-speed combustion fan contribute to reliable year-round performance. Installation instructions are well-regarded for clarity, and the standard 3/4-inch NPT connections match most residential plumbing.

The WiFi functionality is a bonus rather than a core necessity — the LED display panel provides full control without the app. A few users note finding a contractor familiar with tankless installations was the hardest part of the process. The unit runs quietly once operational, with the fan noise comparable to a modern dishwasher.

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The MIZUDO 180,000 BTU propane unit is designed for outdoor installation with an IPX4 weather rating and 380Pa wind pressure resistance, allowing it to operate in cold and windy conditions. At 8.1 GPM, it supports 4–6 outlet points and is suitable for whole-house use.

CSA certification confirms the unit meets safety standards for overheating and accidental flameout protection. The precise temperature control system uses an internal movement sensor to keep water temperature within ±1°F. Owners report easy installation with standard 3/4-inch NPT fittings and say the unit operates quietly compared to older tankless models.

The gas fitting on this unit uses a non-standard thread that requires an adapter if you’re connecting to 1/2-inch pipe — plan for a trip to the hardware store. Some users note the 8.1 GPM is sufficient for simultaneous showers and laundry but may struggle with very large soaking tubs. The included quick-installation poster is genuinely helpful for DIY installation.

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The Ranein natural gas tankless water heater delivers 8.5 GPM from 190,000 BTU in an outdoor-rated cabinet, making it a budget-friendly option for homes needing high flow without paying premium prices. It’s designed for 4–6 outlet points, sufficient for most families.

Owners living in cold climates report the unit survived winter freezes that burst copper pipes elsewhere, thanks to built-in freeze protection. The fan is mounted underneath the unit for safety and noise reduction, and it automatically adjusts speed based on external wind pressure. Several DIY buyers completed installation in under two hours and reported significant drops in monthly propane or gas bills.

The unit is not recommended for elevations above 2,000 feet, which limits its use in mountainous regions. Some users found the instructions vague on certain installation details, particularly around the pressure relief valve. A few reviews mention the unit runs louder than premium brands during high-demand operation.

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The GASLAND Gasmart E offers 7.6 GPM and 199,000 BTU in a compact indoor cabinet that measures just 7.28 inches deep — shallow enough to fit in tight closets or narrow utility spaces. CSA certified with multiple safety functions including overheat, flame-out, and freeze protection.

Owners note the unit heats water faster than the tank it replaced, and the LED display provides real-time temperature readout. The copper heat exchanger with foam insulation is visible through the housing, giving confidence in build quality. Several buyers report successful installation as a straightforward swap for an existing tankless unit, with standard gas and water connections.

The unit is not Energy Star certified, meaning you won’t qualify for federal tax credits. A small number of owners experienced early failure within the first few months, and the hazardous materials classification makes returns complicated if the unit fails. For the price, it’s a capable entry into tankless, but the reliability track record is shorter than established brands like Rheem or Rinnai. A dedicated customer support team is U.S.-based, which helps when issues arise.