Noritz NR66ODNG Outdoor Tankless Water Heater Alternatives: 6 Similar Picks Compared
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If you are researching noritz nr66odng outdoor tankless water heater alternatives, comparing exact specifications ensures you select the right system for your setup. The Noritz NR66ODNG provides a flow rate of 6.6 GPM and a 140,000 BTU heating capacity with a 0.81 UEF rating. Its 36-pound outdoor design frees up indoor utility space and eliminates the need for interior venting ducts.
You might look elsewhere if your household needs a different fuel type like propane, a higher flow rate up to 9.5 GPM, or a larger 190,000 BTU burner. Other buyers may prefer built-in recirculation features or specific exterior dimensions to match existing plumbing rough-ins. The 6 options in this guide were chosen because their specifications directly overlap with the original unit, giving you outdoor-ready choices with comparable capacities, fuel configurations, and efficiency metrics.
Our top pick: Noritz Outdoor Natural Gas Water Heater 6.6 GPM.
How Each Outdoor Alternative Compares
A. O. Smith ProLine XE Outdoor Natural Gas Heater
The A. O. Smith ProLine XE matches the Noritz with a 6.6 GPM flow rate, but it operates at 120,000 BTU instead of 140,000 BTU. This lower thermal output provides less overall heating power. However, it includes clear diagnostics and a copper heat exchanger in a white exterior casing. At 22.9 inches high and 13.9 inches wide, it occupies less vertical and horizontal wall area than the 26.6-by-17.6-inch Noritz, though its 13.9-inch depth is thicker than the Noritz 10.7-inch profile. It is also heavier at 50 pounds versus 36 pounds. You should choose this unit if you want a more compact outdoor wall footprint and moderate natural gas demand.
Rinnai Smart-Circ 6.1 GPM Outdoor Water Heater
The Rinnai Smart-Circ adds an integrated recirculation pump with pattern-learning technology, a capability the Noritz NR66ODNG lacks entirely. It provides a 6.1 GPM flow rate, which is slightly lower than the 6.6 GPM delivered by the Noritz. The physical cabinet measures 24.6 inches tall, 14.1 inches wide, and 10.8 inches deep, making it more compact in height and width than the 26.6-by-17.6-inch Noritz frame. However, the internal pump adds weight, bringing the Rinnai to 56.6 pounds compared to 36 pounds for the Noritz. You should select this model if your outdoor natural gas installation benefits from built-in hot water recirculation to save waiting time at distant taps.
Ranein 8.5 GPM Outdoor Natural Gas Water Heater
The Ranein outdoor heater delivers 190,000 BTU, significantly exceeding the 140,000 BTU rating on the Noritz. It lists an 8.5 GPM flow capacity and standard 3/4-inch connections, along with built-in anti-freeze protection. In exchange for greater heating power, the Ranein is restricted to installations located below 2,000 feet elevation. It also occupies a deeper exterior footprint at 15.1 inches deep, compared to 10.7 inches on the Noritz, and weighs more at 44 pounds versus 36 pounds. You should pick the Ranein if you live at low altitude and need higher continuous thermal capacity to supply multiple bathrooms at the same time from an outdoor natural gas line.
Rinnai 6.1 GPM Outdoor Propane Water Heater
The most fundamental difference with this Rinnai model is fuel type. It runs on liquid propane, while the Noritz NR66ODNG requires natural gas. Like the Noritz, it is built for outdoor, non-condensing installation and delivers up to 6.6 GPM flow. It adds an integrated diagnostic screen to simplify maintenance monitoring. The cabinet measures 24.6 inches high and 14.1 inches wide, giving it a narrower profile than the 26.6-by-17.6-inch Noritz, though it weighs 49.2 pounds compared to 36 pounds for the Noritz. You should select this Rinnai if your home lacks a natural gas hookup and you need an outdoor exterior unit dedicated to propane fuel.
APUS 190,000 BTU Outdoor Natural Gas Water Heater
The APUS water heater upgrades heating performance to 190,000 BTU and provides an 8.1 GPM flow rate, easily outperforming the Noritz unit's 140,000 BTU and 6.6 GPM capacity. Both heaters share an identical 0.81 UEF efficiency rating. The APUS adds smart app-based temperature management, while maintaining an exceptionally slim design at 6.54 inches wide and deep, compared to the 17.6-inch width and 10.7-inch depth of the Noritz. At 42.5 pounds, it is slightly heavier than the 36-pound Noritz. You should choose the APUS if you have a larger household requiring higher simultaneous water flow and desire mobile temperature control in a compact outdoor natural gas package.
Rheem RTG 9.5 GPM Outdoor Natural Gas Tankless Heater
The Rheem RTG delivers significantly more capacity than the Noritz, providing 199,900 BTU per hour and a 9.5 GPM flow rate compared to 140,000 BTU and 6.6 GPM. This extra output supports multiple fixtures running at once. Despite the higher output, the Rheem occupies less exterior space, measuring 20.8 inches tall, 13.5 inches wide, and 9.4 inches deep, against 26.6 by 17.6 by 10.7 inches for the Noritz. It weighs 39.3 pounds, only slightly more than the 36-pound Noritz, and features digital temperature controls. You should pick the Rheem if you have a high-demand home with multiple bathrooms needing substantial simultaneous outdoor natural gas capacity.
Quick picks
Our 7 picks
Noritz Outdoor Natural Gas Water Heater 6.6 GPM
Best for: outdoor natural gas setups needing moderate capacity
- Fuel Type
- Natural Gas
- Flow Rate
- 6.6 Gpm
- BTU
- 140,000 Btuh
- Installation Location
- Outdoor
- Dimensions
- 26.6 x 17.6 x 10.7 inches
- Weight
- 36 pounds
View on Amazon: Noritz Outdoor Natural Gas Water Heater 6.6 GPM
This outdoor natural gas tankless water heater supplies up to 6.6 gallons per minute with a maximum heat output of 140,000 BTU per hour. It features an exterior-mount design measuring 26.6 by 17.6 by 10.7 inches and weighs 36 pounds, eliminating indoor venting requirements. With a 0.81 UEF rating and Low NOx operation, it suits you if you need a dedicated outdoor natural gas setup for mid-sized household hot water demands.
Pros
- 140,000 BTU per hour maximum heat rating
- Maximum flow rate of 6.6 GPM
- 0.81 Uniform Energy Factor rating
- Low NOx emissions performance
Cons
- Outdoor installation only
- Incompatible with liquid propane fuel supplies
- Exterior casing has no finish
Good fit if
- You have an exterior wall space ready for outdoor mounting.
- You use natural gas as your fuel source.
- You need peak hot water delivery up to 6.6 GPM.
Skip if
- You need an indoor water heating installation.
- You require liquid propane instead of natural gas.
- You need hot water flow rates greater than 6.6 GPM.
Verdict: Noritz 6.6 GPM Outdoor Natural Gas Tankless Heater delivers 140,000 BTU per hour and a 0.81 UEF rating in an exterior-only package. It serves homes that require moderate continuous flow without using interior utility space.
Rinnai Smart-Circ 6.1 GPM Outdoor Water Heater
Best for: outdoor installations requiring built-in recirculation
- Fuel Type
- Natural Gas
- Flow Rate
- 6.1 GPM
- Installation Location
- Outdoor
- Dimensions
- 24.6 x 14.1 x 10.8 inches
- Weight
- 56.6 pounds
View on Amazon: Rinnai Smart-Circ 6.1 GPM Outdoor Water Heater
The Rinnai Smart-Circ 6.1 GPM Outdoor Water Heater is an outdoor, natural gas non-condensing unit designed to supply up to five fixtures at once. It measures 24.6 by 14.1 by 10.8 inches and features a built-in recirculation pump that learns your daily usage patterns. This model suits you if you need reliable outdoor water heating with automated recirculation without dedicating interior wall space to plumbing equipment.
Pros
- Built-in recirculation pump with Smart-Circ schedule learning
- Provides up to 6.1 GPM to support five fixtures at once
- Suitcase-sized outdoor dimensions of 24.6 x 14.1 x 10.8 inches
- Up to 15-year heat exchanger and 5-year parts warranty coverage
Cons
- WiFi control requires a separate Controlr module not included in the box
- Labor warranty drops from 5 years to 1 year without 90-day registration
Good fit if
- You need outdoor natural gas heating with an integrated recirculation pump.
- You plan to run up to five plumbing fixtures simultaneously at 6.1 GPM.
Skip if
- You need an indoor unit rather than an outdoor installation.
- You use liquid propane rather than a natural gas line.
Verdict: Rinnai Smart-Circ 6.1 GPM Outdoor Water Heater provides integrated recirculation and outdoor natural gas heating for multiple fixtures. Its compact casing and pattern-learning pump deliver hot water while saving interior wall space.
A. O. Smith ProLine XE Outdoor Natural Gas Heater
Best for: moderate-demand outdoor natural gas water heating
- Fuel Type
- Natural Gas
- Flow Rate
- 6.6 GPM
- BTU
- 120,000 BTU/hr
- Installation Location
- Outdoor
- Dimensions
- 22.9 x 13.9 x 13.9 inches
- Weight
- 50 pounds
View on Amazon: A. O. Smith ProLine XE Outdoor Natural Gas Heater
This outdoor natural gas tankless water heater delivers up to 6.6 GPM with a 120,000 BTU condensing burner. It features a compact wall-mount design measuring 22.9 inches high by 13.9 inches wide and weighs 50 pounds. A commercial-grade copper primary heat exchanger stabilizes your water temperature quickly. If you need a reliable outdoor unit matching standard household demand without consuming interior space, this fits your home.
Pros
- Delivers up to 6.6 GPM continuous hot water flow
- Primary commercial-grade copper heat exchanger transfers heat quickly
- Integrated temperature controls and advanced diagnostics simplify troubleshooting
- Wall-mount profile weighs 50 pounds for space-saving placement
Cons
- Maximum heating capacity is limited to 120,000 BTU
- Configured strictly for outdoor installation
Good fit if
- You need up to 6.6 GPM flow from an exterior natural gas supply.
- You want an outdoor wall-mounted unit with integrated controls and diagnostics.
Skip if
- You require more than 120,000 BTU of heating power.
- You plan to install your water heater indoors.
Verdict: A. O. Smith 6.6 GPM Outdoor Natural Gas Tankless Heater provides steady exterior performance with a responsive copper heat exchanger and clear diagnostics. It is an efficient outdoor solution when 120,000 BTU covers your simultaneous fixture needs.
Ranein 8.5 GPM Outdoor Natural Gas Water Heater
Best for: high-demand outdoor setups below 2,000 feet elevation
- Fuel Type
- Natural Gas
- Flow Rate
- 8.5 GPM
- BTU
- 190,000 BTU/hr
- Installation Location
- Outdoor
- Dimensions
- 24.3 x 15.1 x 8.1 inches
- Weight
- 44 pounds
View on Amazon: Ranein 8.5 GPM Outdoor Natural Gas Water Heater
This outdoor natural gas tankless water heater delivers up to 8.5 GPM with a 190,000 BTU heating capacity. It uses standard 3/4-inch NPT gas and water connections and includes built-in freeze protection with a bottom-mounted blower. Measuring 24.3 by 15.1 by 8.1 inches, it is designed to supply hot water to four to six outlets simultaneously, making it suitable if you need high outdoor flow without indoor venting requirements.
Pros
- Delivers up to 8.5 GPM flow rate with 190,000 BTU heating capacity
- Uses standard 3/4-inch NPT water and gas connections
- Bottom-mounted blower automatically adjusts speed to wind pressure
- Built-in anti-freeze protection prevents internal freezing
Cons
- Not recommended for installations above 2,000 feet elevation
- Requires manual drainage via relief valve when idle in freezing weather
Good fit if
- You live at an elevation under 2,000 feet.
- You have a natural gas supply and run four to six plumbing fixtures.
- You want an outdoor unit with standard 3/4-inch NPT connections.
Skip if
- You live at an altitude higher than 2,000 feet.
- You require an indoor installation or run on propane fuel.
Verdict: Ranein 8.5 GPM Outdoor Natural Gas Water Heater provides high flow and 190,000 BTU capacity for low-altitude outdoor installations. Its standard 3/4-inch connections and anti-freeze feature support multi-bath homes without indoor venting.
Rinnai 6.1 GPM Outdoor Propane Water Heater
Best for: homes needing an outdoor propane water heater
- Fuel Type
- Propane
- Flow Rate
- 6.1 GPM
- Installation Location
- Outdoor
- Dimensions
- 24.6 x 14.1 x 10.8 in
- Venting Type
- Non-Condensing
- Weight
- 49.2 pounds
This outdoor tankless water heater runs on propane rather than natural gas, making it suitable if your property lacks a natural gas line. It delivers a maximum flow rate of 6.1 GPM to supply hot water to up to five fixtures at once. Measuring 24.6 by 14.1 by 10.8 inches and weighing 49.2 pounds, this non-condensing unit mounts outdoors to save interior living space.
Pros
- Supplies up to 6.1 GPM flow rate for up to five fixtures simultaneously
- Compact outdoor profile measuring 24.6 by 14.1 by 10.8 inches
- Built-in LED screen provides service reminders and error codes
- Eligible for a 15-year heat exchanger and 5-year parts warranty
Cons
- WiFi control requires buying a separate Controlr module
- Labor warranty drops from 5 years to 1 year without 90-day registration
- Fuel source is limited to liquid propane
Good fit if
- You use propane fuel rather than natural gas for your home utilities.
- You want an outdoor installation that provides up to 6.1 GPM flow capacity.
Skip if
- You need a heater compatible with a standard residential natural gas connection.
- You plan to mount your water heater indoors rather than outside.
Verdict: Rinnai 6.1 GPM Outdoor Propane Tankless Water Heater delivers reliable flow for locations requiring propane and outdoor installation. Its suitcase-sized frame and integrated diagnostic screen make it a dependable outdoor solution.
APUS 190,000 BTU Outdoor Natural Gas Water Heater
Best for: large households needing smart outdoor natural gas heating
- 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
This outdoor natural gas tankless water heater delivers up to 8.1 GPM with a 190,000 BTU heat output. It features an oxygen-free copper heat exchanger with a 0.81 UEF rating and connects to standard 3/4-inch gas and water lines. You can manage temperatures from 95°F to 149°F using the wired controller or mobile app. It suits you if you need high-capacity outdoor water heating across multiple fixtures simultaneously.
Pros
- Delivers up to 8.1 GPM flow rate and 190,000 BTU output
- Smart temperature control via mobile app and wired controller
- Standard 3/4-inch gas and water connection sizes
- Low 0.79 GPM minimum activation flow rate
Cons
- Outdoor-only mounting design
- Requires an outdoor 120V AC electrical supply
- Two-year warranty duration on components
Good fit if
- You need up to 8.1 GPM to run several hot water fixtures at once.
- You want remote temperature adjustments via smartphone app or wired control.
- You have an outdoor setup with access to natural gas and a 120V outlet.
Skip if
- You plan to mount your water heater indoors.
- You use liquid propane instead of natural gas.
- You want a component warranty period longer than two years.
Verdict: APUS 190,000 BTU Outdoor Natural Gas Tankless Water Heater delivers strong 8.1 GPM output and app-based temperature management for whole-home outdoor installations. Its standard connections and 0.81 UEF rating make it an efficient outdoor natural gas option.
Rheem RTG 9.5 GPM Outdoor Natural Gas Tankless Heater
Best for: large households needing high outdoor flow rates
- Fuel Type
- Natural Gas
- Flow Rate
- 9.5 GPM
- BTU
- 199,900 BTU/hr
- Installation Location
- Outdoor
- Temperature Control
- ±1°F
- Certification
- CSA
View on Amazon: Rheem RTG 9.5 GPM Outdoor Natural Gas Tankless Heater
This outdoor natural gas water heater supplies up to 9.5 GPM at a 35°F temperature rise using 199,900 BTU/hr. Its non-condensing design carries a 0.82 Uniform Energy Factor and mounts directly outside to eliminate indoor exhaust venting. If you run three to four simultaneous showers in a multi-bathroom home, this unit handles high demand reliably.
Pros
- Delivers up to 9.5 GPM at a 35°F temperature rise
- 199,900 BTU/hr maximum heat output for multi-bath demand
- Outdoor wall mounting eliminates indoor exhaust vent runs
- 15-year heat exchanger and 5-year parts warranty
- Digital LED control panel with ±1°F temperature adjustments
Cons
- Non-condensing efficiency capped at 0.82 UEF
- Maximum 9.5 GPM delivery requires a low 35°F temperature rise
- Requires an outdoor installation site
Good fit if
- You need up to 9.5 GPM to run three to four showers at the same time.
- You prefer an exterior wall installation to avoid running indoor vent pipes.
- You want natural gas heating with ±1°F digital temperature adjustments.
Skip if
- You want a condensing unit with an efficiency rating above 0.82 UEF.
- You require an indoor water heater installation.
Verdict: Rheem RTG 9.5 GPM Outdoor Tankless Water Heater suits high-demand households needing up to 9.5 GPM across multiple simultaneous fixtures without routing indoor exhaust pipes.
Specifications side by side
| Spec | Noritz Outdoor Natural Gas Water Heater 6.6 GPM | Rinnai Smart-Circ 6.1 GPM Outdoor Water Heater | A. O. Smith ProLine XE Outdoor Natural Gas Heater | Ranein 8.5 GPM Outdoor Natural Gas Water Heater | Rinnai 6.1 GPM Outdoor Propane Water Heater | APUS 190,000 BTU Outdoor Natural Gas Water Heater | Rheem RTG 9.5 GPM Outdoor Natural Gas Tankless Heater |
|---|---|---|---|---|---|---|---|
| Fuel Type | Natural Gas | Natural Gas | Natural Gas | Natural Gas | Propane | Natural Gas | Natural Gas |
| Flow Rate | 6.6 Gpm | 6.1 GPM | 6.6 GPM | 8.5 GPM | 6.1 GPM | 8.1 GPM | 9.5 GPM |
| BTU | 140,000 Btuh | not specified | 120,000 BTU/hr | 190,000 BTU/hr | not specified | 190,000 BTU | 199,900 BTU/hr |
| Installation Location | Outdoor | Outdoor | Outdoor | Outdoor | Outdoor | Outdoor | Outdoor |
| Voltage | not specified | not specified | not specified | not specified | not specified | 120V AC | not specified |
| Temperature Control | not specified | not specified | not specified | not specified | not specified | 95°F–149°F, ±1°F | ±1°F |
| Certification | not specified | not specified | not specified | not specified | not specified | not specified | CSA |
| Dimensions | 26.6 x 17.6 x 10.7 inches | 24.6 x 14.1 x 10.8 inches | 22.9 x 13.9 x 13.9 inches | 24.3 x 15.1 x 8.1 inches | 24.6 x 14.1 x 10.8 in | 22.48 x 15.51 x 6.54 in | 20.8 x 13.5 x 9.4 inches |
| Venting Type | not specified | not specified | not specified | not specified | Non-Condensing | not specified | Non-Condensing |
| Features | not specified | not specified | not specified | not specified | not specified | not specified | WiFi |
| Weight | 36 pounds | 56.6 pounds | 50 pounds | 44 pounds | 49.2 pounds | 42.5 pounds | 39.3 pounds |
| Color | No Finish | Silver | White | Gray-NG | Silver | Gray | Gray |
| Model | NR662-OD-NG | REU-VEP2125WD-US-N | ATO-140H 100 | RHO19K-NG | REU-VE2125WD-US-P | AP-AWH-W26NG | RTG-95XLN-3 |
| Size | not specified | 6.6 GPM | not specified | 8.5 GPM Outdoor | 6.6 GPM | not specified | 9.5 GPM (No WiFi) |
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Frequently asked questions
Which Noritz NR66ODNG alternative includes built-in recirculation?
You can select the Rinnai Smart-Circ REU-VEP2125WD-US-N if you need integrated recirculation. It includes a pattern-learning pump housed in an exterior casing weighing 56.6 pounds. This setup moves hot water through dedicated lines without requiring you to mount secondary pump equipment inside your home.
Is there a propane alternative to the outdoor Noritz NR66ODNG?
Yes, the Rinnai REU-VE2125WD-US-P provides a direct propane alternative for exterior mounting. It features a non-condensing design, an integrated diagnostic display, and a 49.2-pound frame. You get outdoor setup convenience when your property uses dedicated propane tanks instead of a standard natural gas supply line.
Which outdoor natural gas alternative offers a higher flow rate than 6.6 GPM?
The Rheem RTG-95XLN-3 delivers up to 9.5 GPM, making it a high-capacity non-condensing option. For homes needing higher thermal power, the APUS model provides 190,000 BTU and 8.1 GPM output. Both models supply more volume than moderate 6.6 GPM units for multi-fixture household demands.
Can you manage any of these outdoor alternatives with mobile apps?
Yes, the APUS AP-AWH-W26NG provides app-based temperature management alongside its 190,000 BTU burner. Additionally, the Rheem RTG-95XLN-3 lists WiFi capability in its specifications. These connected options let you check settings or adjust water heat levels remotely without walking outside to the physical exterior heater cabinet.
Do outdoor tankless water heaters work in colder outdoor climates?
Outdoor models operate in exterior environments, but freezing temperatures require careful consideration. The Ranein RHO19K-NG includes dedicated anti-freeze protection to safeguard exterior components. If you live in an area with freezing conditions, ensure your selected outdoor unit features appropriate anti-freeze measures and proper exterior pipe insulation.
Do elevation limits affect outdoor tankless water heater alternatives?
Yes, elevation limits can affect combustion performance on certain models. For example, the Ranein RHO19K-NG specifies operation for outdoor installations below 2,000 feet of elevation. You should always verify the manufacturer altitude ratings before installing any natural gas tankless unit in mountainous or high-elevation locations.