Looking Beyond the Rheem Prestige Condensing Tankless Outdoor? 6 Alternatives Worth a Look
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You might be evaluating rheem prestige condensing tankless outdoor alternatives because the Rheem Prestige excels in cold climates. Its condensing design and freeze protection down to -30 degrees make it ideal for exterior installation. The unit delivers 6.8 GPM of hot water while maintaining a compact footprint. However, you may need higher flow rates or different dimensions for your specific home layout.
The 6 alternatives listed here were chosen because their specifications overlap with the original unit. All options support outdoor natural gas installation and condensing venting. You will find models offering up to 10 GPM for larger households. Some units prioritize compact sizing for tight spaces. Others focus on precise temperature control or wind-resistant combustion. Reviewing these specs helps you match the hardware to your actual hot water demands and installation constraints.
Our top pick: Rheem 6.8 GPM Outdoor Condensing Water Heater.
How the Alternatives Compare
Rinnai RU160eN 9 GPM Outdoor Natural Gas
The Rinnai RU160eN delivers 9 GPM, offering 2.2 GPM more flow than the Rheem Prestige. This higher output suits large households running multiple showers simultaneously. It shares the outdoor condensing natural gas design, ensuring similar efficiency and space-saving benefits. The Rinnai is slightly wider at 14.8 inches but shorter in height. You gain volume but lose the specific freeze protection rating found in the Rheem model. Choose this if your primary need is high-volume hot water for busy homes rather than extreme cold weather resilience.
A. O. Smith 10 GPM Outdoor Condensing Tankless Heater
The A. O. Smith unit provides 10 GPM, the highest flow rate in this group. It outputs 3.2 GPM more than the Rheem Prestige, making it ideal for very large homes. It uses natural gas and condensing venting for outdoor installation. The unit is narrower and lighter than the Rheem, weighing only 59 pounds. You trade the Rheem’s known freeze protection for higher capacity. This model fits buyers who prioritize maximum hot water output above all else. The compact footprint allows for easier placement in tight outdoor spaces compared to the bulkier Rheem design.
Takagi Outdoor 8 GPM Natural Gas Water Heater
The Takagi T-H3S-OS-N offers 8 GPM, providing 1.2 GPM more flow than the Rheem. It maintains the outdoor condensing natural gas configuration. The unit is significantly narrower, measuring 11.3 inches in length, which saves space. It weighs less than the Rheem, making installation slightly easier. You gain a higher flow rate and a slimmer profile. The trade-off is the lack of specific freeze protection data in the provided specs. This model suits users who want more hot water than the Rheem provides but still need a compact outdoor unit for natural gas.
Takagi T-H3M Outdoor Natural Gas Heater
The Takagi T-H3M-OS-N is the most compact option, weighing just 44 pounds. It shares the outdoor condensing natural gas design with the Rheem. However, its flow rate is not explicitly stated in the specs, so you cannot confirm if it matches the Rheem’s 6.8 GPM. The unit is narrower and lighter, making it ideal for tight spaces. You gain significant space savings and portability. The trade-off is potentially lower flow capacity and the absence of confirmed freeze protection details. Choose this if space and weight are your primary constraints for an outdoor natural gas installation.
Ranein 8.5 GPM Outdoor Natural Gas Water Heater
The Ranein model lists 8.5 GPM in its size spec, suggesting higher capacity than the Rheem. It is designed for outdoor natural gas use. The unit is narrower and lighter than the Rheem, weighing 44 pounds. It features wind-resistant combustion and anti-freeze safety, addressing outdoor challenges. You gain a potentially higher flow rate and specific wind resistance features. The trade-off is the lack of detailed condensing venting specs in the provided data. This model fits buyers who need robust outdoor performance with good flow and wind protection, prioritizing these over the Rheem’s established brand metrics.
APUS 190,000 BTU Outdoor Natural Gas Water Heater
The APUS heater offers 190,000 BTU, providing strong heating power for outdoor natural gas use. It is the narrowest unit at 6.54 inches, saving significant space. It weighs only 42.5 pounds, making it the lightest option. The unit supports precise temperature control via smart app management. You gain advanced connectivity and a very compact footprint. The trade-off is the lack of explicit GPM flow rate data and freeze protection specs. Choose this if you prioritize smart control features and minimal space usage over confirmed high flow rates or cold weather protection details.
Quick picks
Our 7 picks
Rheem 6.8 GPM Outdoor Condensing Water Heater
Best for: cold climate outdoor installations
- Fuel Type
- Natural Gas
- Flow Rate
- 6.8 GPM
- Installation Location
- Outdoor
- Dimensions
- 28.5 x 9.75 x 27.5 inches
- Venting Type
- Condensing
- Weight
- 77 pounds
View on Amazon: Rheem 6.8 GPM Outdoor Condensing Water Heater Affiliate link
This outdoor natural gas unit delivers 6.8 GPM with condensing efficiency. It measures 28.5 x 9.75 x 27.5 inches and weighs 77 pounds. The system includes leak detection and freeze protection down to -30 degrees. It suits households needing reliable outdoor hot water without a tank. You get space savings and low operating costs through high efficiency.
Pros
- 6.8 GPM flow rate for natural gas
- Condensing technology for high efficiency
- Freeze protection down to -30 degrees
- Water and gas leak detection system
Cons
- Lower flow rate than 8-9 GPM competitors
- Heavier at 77 pounds than many alternatives
- No remote control or app mentioned in data
Good fit if
- You need an outdoor unit in freezing climates
- You want high energy efficiency for lower costs
- You have space for a 77-pound unit
Skip if
- You need more than 6.8 GPM simultaneously
- You prefer a lighter, more compact unit
- You want smart home integration features
Verdict: Rheem 6.8 GPM Outdoor Tankless fits homes prioritizing freeze protection and efficiency over maximum flow rate. It is ideal for cold climates where outdoor installation is required.
Rinnai RU160eN 9 GPM Outdoor Natural Gas
Best for: high-flow outdoor needs
- Fuel Type
- Natural Gas
- Flow Rate
- 9 GPM
- Installation Location
- Outdoor
- Dimensions
- 33.9 x 14.8 x 22.1 inches
- Venting Type
- Condensing
- Weight
- 71 pounds
View on Amazon: Rinnai RU160eN 9 GPM Outdoor Natural Gas Affiliate link
The Rinnai RU160eN is a natural gas tankless water heater designed for outdoor installation. It delivers 9 GPM of hot water, supporting up to six appliances simultaneously. Its condensing design achieves an ENERGY STAR qualification with a 0.95 Uniform Energy Factor. The unit measures 33.9 by 14.8 by 22.1 inches and weighs 71 pounds. It includes Circ-Logic technology for recirculation compatibility. This model suits homes needing high flow rates in a compact, efficient package.
Pros
- 9 GPM flow rate supports multiple simultaneous uses
- Condensing design offers 0.95 Uniform Energy Factor
- 15-year heat exchanger warranty for residential use
- Circ-Logic compatible for scheduled or on-demand recirculation
Cons
- WiFi monitoring requires a separate Controlr module
- Professional installation is strongly recommended
- Heavier build at 71 pounds compared to lighter units
Good fit if
- You need high flow for multiple bathrooms
- You want ENERGY STAR efficiency
- You have space for outdoor condensing installation
Skip if
- You prefer indoor installation only
- You want built-in WiFi without extra parts
- You need propane fuel type
Verdict: Rinnai RU160eN 9 GPM Outdoor delivers reliable high-volume hot water with strong efficiency. It fits large households that prioritize flow rate and energy savings over compact indoor placement.
A. O. Smith 10 GPM Outdoor Condensing Tankless Heater
Best for: High flow outdoor needs
- Fuel Type
- Natural Gas
- Flow Rate
- 10.0 GPM
- BTU
- 199,000 BTU/hr
- Installation Location
- Outdoor
- Dimensions
- 23.6 x 17.8 x 17.8 inches
- Venting Type
- Condensing
View on Amazon: A. O. Smith 10 GPM Outdoor Condensing Tankless Heater Affiliate link
This outdoor natural gas unit delivers 10.0 GPM at 199,000 BTU. It uses condensing technology for high efficiency. The copper heat exchanger offers better heat transfer than steel. It includes a wall-mounted remote controller. This model suits homes needing high flow rates for multiple bathrooms.
Pros
- 10.0 GPM flow rate
- 199,000 BTU input
- Copper heat exchanger
- Includes wall remote
- Condensing efficiency
Cons
- Heavier than some competitors
- Larger physical footprint
- No smart home integration listed
Good fit if
- You need 10 GPM flow
- You have outdoor space
- You want copper internals
Skip if
- You need indoor use
- You want propane fuel
- You need compact size
Verdict: A. O. Smith 10 GPM Outdoor Tankless fits large homes needing maximum hot water output. Its copper core and remote control add value for serious users.
Takagi Outdoor 8 GPM Natural Gas Water Heater
Best for: outdoor homes needing 8 GPM
- Fuel Type
- Natural Gas
- Flow Rate
- 8 GPM
- Installation Location
- Outdoor
- Dimensions
- 24.9 x 17.8 x 11.3 inches
- Venting Type
- Condensing
- Capacity
- 8 Gallon
View on Amazon: Takagi Outdoor 8 GPM Natural Gas Water Heater Affiliate link
This Takagi unit delivers 8 gallons per minute of hot water using natural gas. It is designed for outdoor installation and uses condensing technology for high efficiency. The compact size measures 24.9 by 17.8 by 11.3 inches. It meets ultra-low NOx emission standards. You get endless hot water without a pilot light. This model suits homes needing reliable outdoor heating with strict emissions compliance.
Pros
- 8 GPM flow rate
- Condensing high efficiency
- Ultra-low NOx emissions
- No pilot light
Cons
- Outdoor installation only
- Natural gas fuel type
- Lower flow than 9 GPM competitors
Good fit if
- You need an outdoor unit
- You require 8 GPM capacity
- You want ultra-low emissions
Skip if
- You need indoor installation
- You require propane fuel
- You need 9 GPM flow
Verdict: Takagi T-H3S-OS-N 8 GPM Outdoor provides steady hot water for outdoor setups. It fits buyers who prioritize efficiency and emissions over maximum flow rate.
Takagi T-H3M Outdoor Natural Gas Heater
Best for: compact outdoor natural gas installations
- Fuel Type
- Natural Gas
- Installation Location
- Outdoor
- Dimensions
- 29.5 x 13.1 x 17.8 inches
- Venting Type
- Condensing
- Weight
- 44 pounds
View on Amazon: Takagi T-H3M Outdoor Natural Gas Heater Affiliate link
The Takagi T-H3M-OS-N is a condensing outdoor tankless water heater designed for natural gas. It measures 29.5 inches tall, 13.1 inches wide, and 17.8 inches deep, weighing 44 pounds. This unit is built for outdoor installation and uses condensing technology for efficiency. It suits homeowners who need a compact, durable hot water solution for exterior mounting without requiring indoor space.
Pros
- Condensing technology for high efficiency
- Compact dimensions: 29.5 x 13.1 x 17.8 inches
- Lightweight at 44 pounds
- Designed specifically for outdoor installation
Cons
- Does not list a flow rate (GPM) in specifications
- No remote control or app connectivity mentioned
- Lacks digital display details in provided data
Good fit if
- You need a compact unit for outdoor mounting
- You prefer natural gas for energy efficiency
- You want a lightweight, space-saving design
Skip if
- You require a known high flow rate for multiple showers
- You need smart home integration or remote control
- You are installing indoors where venting differs
Verdict: Takagi T-H3M-OS-N Outdoor Natural Gas Heater offers a compact, efficient condensing solution for exterior use. It fits buyers prioritizing space savings and natural gas efficiency over smart features or high flow rates.
Ranein 8.5 GPM Outdoor Natural Gas Water Heater
Best for: outdoor homes needing 4-6 simultaneous outlets
- Fuel Type
- Natural Gas
- Flow Rate
- 8.5 GPM
- BTU
- 190,000 BTU
- Installation Location
- Outdoor
- Dimensions
- 24.3 x 15.1 x 15.1 in
- Weight
- 44 pounds
View on Amazon: Ranein 8.5 GPM Outdoor Natural Gas Water Heater Affiliate link
The Ranein RHO19K-NG delivers 8.5 GPM at 190,000 BTU for outdoor natural gas use. Its compact 24.3 x 15.1 x 8.1 inch frame suits 4-6 outlets. The internal fan adjusts to wind pressure for stable combustion. Anti-freeze protection prevents internal cracking in cold weather. It weighs 44 pounds and uses standard 3/4 inch fittings for installation.
Pros
- High 8.5 GPM flow rate supports multiple simultaneous outlets.
- 190,000 BTU/hr heating capacity provides rapid hot water.
- Internal fan adjusts to wind pressure for safe combustion.
- Anti-freeze protection prevents internal damage in cold weather.
- Compact dimensions save space on exterior walls.
Cons
- Not recommended for altitudes over 2,000 feet.
- Requires manual draining of the pressure relief valve if unused in cold weather.
- Lower flow rate than the 9 GPM Rinnai RU160eN on this list.
Good fit if
- You need high flow for 4-6 outlets.
- You install in a low-altitude outdoor location.
- You want anti-freeze protection for winter use.
Skip if
- You live above 2,000 feet in elevation.
- You require automatic winterization without manual draining.
- You need more than 8.5 GPM for high demand.
Verdict: The Ranein 8.5 GPM Outdoor Gas Heater offers strong performance for families needing multiple simultaneous outlets in low-altitude areas. It is a solid choice if you prioritize wind-resistant combustion and anti-freeze safety over maximum flow capacity.
APUS 190,000 BTU Outdoor Natural Gas Water Heater
Best for: Precise outdoor temperature control
- Fuel Type
- Natural Gas
- Flow Rate
- 8.1 GPM
- BTU
- 190,000 BTU
- Installation Location
- Outdoor
- Voltage
- 120V AC
- Temperature Control
- 95°F–149°F, ±1°F
View on Amazon: APUS 190,000 BTU Outdoor Natural Gas Water Heater Affiliate link
The APUS unit delivers 8.1 GPM at 190,000 BTU for whole-house outdoor use. It features a compact 22.5-inch height and precise temperature control within ±1°F. You can adjust settings via the Tuya app or a wired controller. The oxygen-free copper heat exchanger supports staged combustion for efficiency. It includes freeze and overheat safeguards for reliable operation.
Pros
- 8.1 GPM flow rate for multiple fixtures
- Precise ±1°F temperature stability
- Smart control via Tuya app or wired controller
- Compact 22.5-inch outdoor footprint
Cons
- 2-year warranty is shorter than industry leaders
- Requires 120V AC power connection
- Minimum flow rate of 0.79 GPM may struggle with very low pressure
Good fit if
- You need precise temperature control for sensitive fixtures
- You want app-based remote adjustment
- You have a standard 120V outdoor outlet
Skip if
- You require a longer warranty period
- You cannot provide 120V AC power
- You need higher flow than 8.1 GPM
Verdict: APUS 190k BTU Outdoor Natural Gas Heater offers precise smart control and strong flow for outdoor installations. It fits users who prioritize app management and temperature stability over extended warranty coverage.
Specifications side by side
| Spec | Rheem 6.8 GPM Outdoor Condensing Water Heater | Rinnai RU160eN 9 GPM Outdoor Natural Gas | A. O. Smith 10 GPM Outdoor Condensing Tankless Heater | Takagi Outdoor 8 GPM Natural Gas Water Heater | Takagi T-H3M Outdoor Natural Gas Heater | Ranein 8.5 GPM Outdoor Natural Gas Water Heater | APUS 190,000 BTU Outdoor Natural Gas Water Heater |
|---|---|---|---|---|---|---|---|
| Fuel Type | Natural Gas | Natural Gas | Natural Gas | Natural Gas | Natural Gas | Natural Gas | Natural Gas |
| Flow Rate | 6.8 GPM | 9 GPM | 10.0 GPM | 8 GPM | not stated | 8.5 GPM | 8.1 GPM |
| BTU | not stated | not stated | 199,000 BTU/hr | not stated | not stated | 190,000 BTU | 190,000 BTU |
| Installation Location | Outdoor | Outdoor | Outdoor | Outdoor | Outdoor | Outdoor | Outdoor |
| Voltage | not stated | not stated | not stated | not stated | not stated | not stated | 120V AC |
| Temperature Control | not stated | not stated | not stated | not stated | not stated | not stated | 95°F–149°F, ±1°F |
| Dimensions | 28.5 x 9.75 x 27.5 inches | 33.9 x 14.8 x 22.1 inches | 23.6 x 17.8 x 17.8 inches | 24.9 x 17.8 x 11.3 inches | 29.5 x 13.1 x 17.8 inches | 24.3 x 15.1 x 15.1 in | 22.48 × 15.51 × 6.54 in |
| Venting Type | Condensing | Condensing | Condensing | Condensing | Condensing | not stated | not stated |
| Capacity | not stated | not stated | not stated | 8 Gallon | not stated | not stated | not stated |
| Weight | 77 pounds | 71 pounds | 59 pounds | not stated | 44 pounds | 44 pounds | 42.5 pounds |
| Color | Gray | Outdoor Installation | White | White | White | Gray-NG | Gray |
| Model | RTGH-68XLN-2 | RU160eN | ATO-540H-N 100 | T-H3S-OS-N | TH3MOSNG | RHO19K-NG | AP-AWH-W26NG |
| Size | not stated | 9 GPM | not stated | Medium | not stated | 8.5 GPM Outdoor | not stated |
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Frequently asked questions
Which outdoor tankless water heater has the highest flow rate?
The A. O. Smith model delivers 10 GPM, the highest output in this list. It is designed for large homes needing maximum hot water volume. This unit operates at 199,000 BTU to support its high flow capacity. It is a strong choice if you prioritize output over compact size.
What is the most compact outdoor tankless heater on this list?
The APUS unit measures just 6.54 inches in width and length. It weighs 42.5 pounds, making it the lightest option available. This compact footprint suits tight exterior spaces. It provides 190,000 BTU of power despite its small physical size.
Which unit is best for cold climate freeze protection?
The Rheem 6.8 GPM Outdoor model is ideal for cold climates. It features freeze protection down to -30 degrees. This condensing unit is built specifically for exterior installation in harsh weather. It balances efficiency with reliable freeze safety for outdoor use.
Do any of these heaters offer remote control capabilities?
The A. O. Smith 10 GPM model includes a remote control. This feature adds value for users who want convenient operation. It allows you to adjust settings without accessing the main unit directly. This is useful for high-output outdoor installations.
Which alternative is best for high-flow outdoor needs on a budget?
The Rinnai RU160eN is rated as the best budget option for high flow. It delivers 9 GPM, which supports large households. This natural gas unit uses condensing technology for efficiency. It offers strong performance for exterior setups without the premium price tag.
Which heater is best for precise temperature control via an app?
The APUS 190,000 BTU heater offers precise smart control. It fits users who prioritize app management for temperature stability. This unit allows you to monitor and adjust settings remotely. It is a solid choice for those who want digital convenience in an outdoor setup.
Is there a tankless heater suitable for 4-6 simultaneous outlets?
The Ranein 8.5 GPM model is suitable for 4-6 simultaneous outlets. It is designed for low-altitude areas with strong performance. This unit prioritizes wind-resistant combustion and anti-freeze safety. It provides reliable hot water for families with multiple concurrent water demands.
Which unit is best for compact outdoor natural gas installations?
The Takagi T-H3M offers a compact, efficient condensing solution. It weighs only 44 pounds and fits small exterior spaces. This natural gas heater prioritizes space savings over high flow rates. It is ideal for buyers who need a smaller footprint for their outdoor installation.