What it delivers
The Westinghouse AMZ-HS120A1G-NG 120,000 BTU Natural Gas Outdoor Tankless Water Heater is an outdoor gas tankless with a 120,000 BTU/h burner and a stated maximum flow of 5.1 GPM.
Flow depends on how cold the incoming water is. Our estimate from its input: 4.1 GPM at a 45°F rise, falling to 2.6 GPM at 70°F, which is 1 shower at 2 GPM on a cold-climate winter day. Size it to your fixtures and climate.
Gas load at full fire: about 116 cubic feet of natural gas an hour. An older half-inch line that already feeds a furnace often can't spare that, so have a gas fitter check the pipe size and run.
Outdoor units vent straight out of the cabinet, which saves the vent run and the wall penetration; plan for freeze protection and a pipe cover where winters bite.
The listing describes its venting as: outdoor installation.
Also on the listing: connections: 3/4" npt; material: Cold Rolled Steel; model: AMZ-HS120A1G-NG.
The listing gives dimensions of 15.5 in (W) x 23.9 in (H).
Right unit for this house?
Install it when
- One shower at a time in cold climates
- Replacing a gas tank heater
Look at another unit when
- More than 1 winter shower at once
- Homes without a gas line
Strengths and trade-offs
Strengths
- 120,000 BTU/h input
- Up to 5.1 GPM
- No vent pipe
Trade-offs
- Gas line may need upsizing
- Needs freeze protection outdoors
- Annual flushing on hard water
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 | AMZ-HS120A1G-NG | Retailer |
|---|---|---|
| Dimensions (seller) | 15.5"W x 23.9"H | Retailer |
| Features (seller) | 2-5 Years After-Sale Support, CSA-Certificated, Easy to Install, Remote Control, ±1℉ Temp Control | Retailer |
| Voltage | 120 V AC | Retailer |
| Max flow (maker) | 5.1 GPM | Retailer |
| Input (maker) | 120,000 BTU/h | Retailer |
| Material | Cold Rolled Steel | Retailer |
| Fuel | natural gas | Retailer |
| Venting | outdoor installation | Retailer |
| Connections | 3/4" npt | Retailer |
Rival units at this flow
More gas tankless water heaters rated for similar demand
- APUS AP-AWH-W26LPG 190,000 BTU Propane Outdoor Tankless Water Heater
- APUS AP-AWH-W26NG 190,000 BTU Natural Gas Outdoor Tankless Water Heater
- VancEpic V-RHO19K-NG 190,000 BTU Natural Gas Outdoor Tankless Water Heater
- Ranein RHO19K-LPG 190,000 BTU Propane Outdoor Tankless Water Heater
Full gas tankless water heaters spec grid · Every Westinghouse unit in the catalog
Final verdict
A practical outdoor gas tankless for one shower at a time in cold climates.
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