What it delivers
The A. O. Smith ATI-540P-N 199,000 BTU Natural Gas Tankless Water Heater is a non-condensing gas tankless with a 199,000 BTU/h burner and a stated maximum flow of 10.0 GPM.
Flow depends on how cold the incoming water is. Our estimate from its input: 6.8 GPM at a 45°F rise, falling to 4.4 GPM at 70°F, which is 2 showers at 2 GPM on a cold-climate winter day. Check it against your own fixtures.
The line must deliver about 192 cubic feet of natural gas an hour when it fires flat out. The requirement calculator adds it up; a licensed fitter confirms the pipe.
Non-condensing indoor units run hot exhaust and vent in the maker's listed vent system (often stainless Category III), which costs more than plastic.
Also on the listing: features: Overheat Protection; recirculation: recirculation pump; material: Alloy Steel; model: ATI-540P-N; warranty: 15-Year Limited Warranty.
The listing gives dimensions of 17.75 in (W) x 23.63 in (H), a weight of 61 lb and product only in the box.
Warranty, per the listing: 15-Year Limited Warranty.
Right unit for this house?
Install it when
- Houses running 2 showers at once in winter
- Replacing a gas tank heater
Look at another unit when
- More than 2 winter showers at once
- Homes without a gas line
Strengths and trade-offs
Strengths
- 199,000 BTU/h input
- Up to 10.0 GPM
Trade-offs
- Gas line may need upsizing
- Stainless venting costs more
- Scale builds up without flushing
Install limits
- Figures are the maker's or seller's own. Flow at a rise is our estimate from the input; gas, venting and electrical work needs a licensed professional.
Rated performance
Every figure below comes from the source shown in brackets. Where the maker doesn't state something, we say so instead of estimating.
| Model number | ATI-540P-N | Retailer |
|---|---|---|
| Dimensions (seller) | 17.75"W x 23.63"H | Retailer |
| Features (seller) | Overheat Protection | Retailer |
| Voltage | 120 V | Retailer |
| Max flow (maker) | 10 GPM | Retailer |
| Input (maker) | 199,000 BTU/h | Retailer |
| Product weight | 61 lb | Retailer |
| Material | Alloy Steel | Retailer |
| Warranty | 15-Year Limited Warranty | Retailer |
| Fuel | ng | Retailer |
| Recirculation | recirculation pump | Retailer |
Rival units at this flow
More gas tankless water heaters rated for similar demand
Final verdict
A practical non-condensing gas tankless for houses running 2 showers at once in winter.
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