Noritz vs A. O. Smith: Tankless Water Heaters Compared by Specs
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When comparing noritz vs a o smith tankless water heater, you see two strong natural gas options. Both units deliver high BTU output for reliable hot water. The main difference lies in flow rate and physical design. Noritz offers a higher flow rate and indoor/outdoor flexibility. A. O. Smith focuses on condensing efficiency and a more compact outdoor footprint. This guide breaks down the specs to help you decide.
Key differences
| Aspect | Noritz EZ Series Pro 11.1 GPM Natural Gas Heater | A. O. Smith 10 GPM Outdoor Condensing Tankless Heater |
|---|---|---|
| Flow Rate | 11.1 GPM | 10.0 GPM |
| Installation Location | Indoor/Outdoor | Outdoor |
| Venting Type | not listed | Condensing |
| Voltage | 120 V | not listed |
| Weight | 77.2 pounds | 59 pounds |
Which one should you choose?
Choose Noritz EZ Series Pro 11.1 GPM Natural Gas Heater if
- You need the highest possible flow rate for multiple simultaneous showers.
- You want a unit that can be installed indoors or outdoors.
- You prefer a lighter footprint is less critical than maximum capacity.
Choose A. O. Smith 10 GPM Outdoor Condensing Tankless Heater if
- You want condensing technology for higher energy efficiency.
- You have limited space and need a more compact outdoor unit.
- You value advanced diagnostics and a remote temperature controller.
Verdict: Choose the Noritz if you prioritize maximum flow rate and flexible installation locations. Pick the A. O. Smith if you want condensing efficiency and a smaller outdoor footprint. Both models deliver strong performance for your home.
Noritz vs A. O. Smith Specs
Flow Rate
Flow rate determines how many fixtures can run at once. The Noritz GQ-C3261WX-FF provides 11.1 GPM. The A. O. Smith ATO-540H-N delivers 10.0 GPM. This difference matters for larger households. Higher flow supports more simultaneous showers or appliance use. Noritz leads in pure volume. You get nearly one extra gallon per minute. This helps when multiple bathrooms are active. A. O. Smith still meets standard needs for most homes. But if you need maximum capacity, Noritz has the edge.
BTU Output
Both units use natural gas and offer high heating power. Noritz outputs 199,900 BTU. A. O. Smith outputs 199,000 BTU. The difference is negligible in practice. Both are rated at 199,000 BTU for most comparisons. This level of power handles standard residential demands. You will not notice a difference in heating speed. Both units are designed for high-efficiency condensing or direct venting. The near-identical BTU ratings mean performance relies more on flow rate. This round is a clear tie for heating power.
Installation Location
Location flexibility affects where you can place the unit. Noritz is rated for indoor and outdoor use. A. O. Smith is listed for outdoor use only. This is a significant distinction. If you have limited exterior wall space, Noritz allows interior mounting. A. O. Smith requires outdoor placement. This may restrict options in colder climates or tight spaces. Noritz offers more versatility. You can choose based on your home layout. A. O. Smith is strictly outdoor. This limits placement choices for some buyers.
Physical Dimensions
Space constraints often dictate choice. Noritz measures 11.8 x 18.1 x 26.1 inches. A. O. Smith measures 23.6 x 17.8 x 17.8 inches. Noritz is taller but narrower and shallower. A. O. Smith is wider and deeper but shorter. Noritz fits better in tight vertical spaces. A. O. Smith has a more compact footprint on the wall. Weight also differs. Noritz weighs 77.2 pounds. A. O. Smith weighs 59 pounds. Lighter units are easier to mount. A. O. Smith wins on weight. Noritz wins on height efficiency.
Voltage
Electrical requirements vary by model. Noritz specifies 120 Volts. A. O. Smith does not list voltage in the provided data. This makes direct comparison difficult. You must check the manual for A. O. Smith specifics. Noritz clearly states its electrical need. This ensures compatibility with standard circuits. A. O. Smith likely requires similar power. However, without explicit data, you cannot confirm. Noritz provides clearer electrical specifications. This reduces installation guesswork. A. O. Smith leaves this detail unlisted in the summary.
Which tankless heater fits your home
Needs max flow for large homes
The Noritz unit delivers 11.1 GPM, which is higher than the A. O. Smith model. This extra flow supports more simultaneous fixtures. If you have a large household with multiple bathrooms, this higher capacity ensures consistent hot water pressure. The 199,900 BTU output supports this robust performance for your daily needs.
Wants compact outdoor installation
The A. O. Smith model is lighter at 59 pounds and has a narrower width. Its condensing technology offers high efficiency. This unit includes a wall mount temperature remote controller for easy adjustments. If you prefer a lighter, more compact outdoor unit with advanced diagnostics, this spec-focused choice fits your installation requirements.
Prefers indoor or outdoor flexibility
The Noritz heater is rated for both indoor and outdoor installation. This dual capability gives you more placement options compared to the A. O. Smith model, which is listed for outdoor use only. If your installation space is flexible or you need to switch locations, this versatility is a key practical advantage for your setup.
Values heat exchanger durability
The A. O. Smith features a commercial-grade copper heat exchanger. Copper provides better heat transfer than steel, which can improve longevity. It also includes a 15-year limited warranty on the heat exchanger for residential use. If you prioritize long-term component durability and specific material quality, this spec is a strong consideration for your purchase.
The products compared
Noritz EZ Series Pro 11.1 GPM Natural Gas Heater
Best for: Large households with high hot water demand
- Fuel Type
- Natural Gas
- Flow Rate
- 11.1 GPM
- BTU
- 199,900 BTU
- Installation Location
- Indoor/Outdoor
- Voltage
- 120 V
- Dimensions
- 11.8 x 18.1 x 26.1 in
View on Amazon: Noritz EZ Series Pro 11.1 GPM Natural Gas Heater Affiliate link
This Noritz unit delivers 11.1 GPM at 199,900 BTU using natural gas. It runs on 120 volts and measures 11.8 x 18.1 x 26.1 inches. The silver unit weighs 77.2 pounds. It suits homes needing high flow for multiple fixtures. You can install it indoors or outdoors. The compact design fits tight spaces while providing reliable hot water.
Pros
- High 11.1 GPM flow rate
- 199,900 BTU heating power
- Indoor and outdoor installation options
- Compact 11.8-inch depth
Cons
- Requires 120-volt electrical connection
- Heavier at 77.2 pounds
- Limited to natural gas fuel
Good fit if
- You need high flow for multiple bathrooms
- You want indoor or outdoor flexibility
- You have natural gas available
Skip if
- You require propane compatibility
- You need electric-only operation
- You have limited vertical clearance
Verdict: Noritz GQ-C3261WX 11.1 GPM Natural Gas fits homes with high hot water demand. It provides strong performance for simultaneous use in large households.
A. O. Smith 10 GPM Outdoor Condensing Tankless Heater
Best for: high-efficiency outdoor installations
- 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 A. O. Smith unit delivers 10.0 GPM of hot water using 199,000 BTU of natural gas. It uses condensing technology for a high 0.94 Uniform Energy Factor. The outdoor design includes a wall-mounted temperature remote controller. It fits northern climates for three bathrooms or southern homes for four. You get a copper heat exchanger for stable temperatures and efficient heat transfer.
Pros
- 10.0 GPM flow rate for multiple fixtures
- 0.94 Uniform Energy Factor rating
- Includes wall mount temperature remote controller
- Commercial-grade copper heat exchanger
- Flexible venting up to 100 feet
Cons
- Lower flow rate than the Noritz GQ-C3261WX-FF
- Heavier at 59 pounds
- Outdoor installation only
Good fit if
- You need a high-efficiency condensing unit
- You want a remote temperature controller included
- You are installing outdoors in a northern climate
Skip if
- You require a flow rate above 10 GPM
- You need an indoor installation option
- You prefer a lighter unit under 50 pounds
Verdict: A. O. Smith 10 GPM Outdoor Natural Gas suits you if you prioritize energy efficiency and included remote control over maximum flow speed.
Specifications side by side
| Spec | Noritz EZ Series Pro 11.1 GPM Natural Gas Heater | A. O. Smith 10 GPM Outdoor Condensing Tankless Heater |
|---|---|---|
| Fuel Type | Natural Gas | Natural Gas |
| Flow Rate | 11.1 GPM | 10.0 GPM |
| BTU | 199,900 BTU | 199,000 BTU/hr |
| Installation Location | Indoor/Outdoor | Outdoor |
| Voltage | 120 V | not stated |
| Dimensions | 11.8 x 18.1 x 26.1 in | 23.6 x 17.8 x 17.8 inches |
| Venting Type | not stated | Condensing |
| Weight | 77.2 pounds | 59 pounds |
| Color | Silver | White |
| Model | GQ-C3261WX-FF US NG | ATO-540H-N 100 |
Frequently asked questions
Which tankless heater is better for large families, Noritz or A. O. Smith?
Noritz is the better choice for large families. The Noritz GQ-C3261WX-FF delivers 11.1 GPM. This higher flow rate supports simultaneous use in multiple bathrooms. The A. O. Smith model provides 10 GPM. It may struggle if several fixtures run at once in a busy household.
Can I install both Noritz and A. O. Smith units outdoors?
Yes, both units are designed for outdoor installation. The Noritz GQ-C3261WX-FF is rated for outdoor use. The A. O. Smith ATO-540H-N is also an outdoor condensing heater. Ensure your outdoor location meets local code requirements for clearance and protection from the elements.
What is the difference in size between the Noritz and A. O. Smith heaters?
The Noritz unit is taller and narrower. It measures 26.1 inches in height and 18.1 inches in width. The A. O. Smith unit is shorter and wider. It stands 23.6 inches tall and spans 17.8 inches in width. Check your installation space carefully before deciding.
Does the A. O. Smith heater come with a remote control?
Yes, the A. O. Smith ATO-540H-N includes a remote control. This feature allows you to adjust settings from a distance. The provided data does not mention a remote for the Noritz GQ-C3261WX-FF. You may need to access the unit directly to change settings on the Noritz model.
Which unit is lighter to handle during installation?
The A. O. Smith heater is lighter. It weighs 59 pounds. The Noritz unit weighs 77.2 pounds. The weight difference may matter if you need to lift the unit into a tight space or onto a roof mount. Consider your physical ability to handle the heavier Noritz model.
Is the Noritz heater condensing or non-condensing?
The provided data does not specify the venting type for the Noritz GQ-C3261WX-FF. It only lists it as a natural gas outdoor heater. The A. O. Smith model is explicitly identified as a condensing heater. Condensing units often offer higher efficiency by capturing heat from exhaust gases.
What fuel type do both of these tankless heaters use?
Both heaters use natural gas. The Noritz GQ-C3261WX-FF is designed for natural gas. The A. O. Smith ATO-540H-N also runs on natural gas. You will need an existing natural gas line and proper venting for either unit. They are not compatible with propane unless converted by a professional.