The Navien NPE-210S2 is a condensing tankless water heater from Navien's NPE-2 series. Same cabinet and the same pair of stainless steel heat exchangers as the NPE-210A2, without the internal pump — which is why it carries the higher efficiency rating of the two.
Rated input is 12,000 - 180,000 BTU/h on natural gas or propane — the unit is certified for both. It modulates from 180,000 BTU/h all the way down to 12,000, so it is not running at full fire to fill a sink.
How much hot water you actually get
Navien rates every tankless unit by temperature rise, because the colder the incoming water, the less of it one burner can heat. Here is what the NPE-210S2 delivers:
| Temperature rise |
Flow rate |
Typical use |
| 35°F |
10.1 GPM |
Warm-climate groundwater, or a preheated feed |
| 45°F |
7.8 GPM |
The usual design point across most of the U.S. |
| 67°F |
5.3 GPM |
Northern winter, incoming water near 40°F |
Sized against a 2.5 GPM showerhead, the 67°F column is worth roughly 2 showers at once on the coldest day of the year, and more than that the rest of the year. Size to the 67°F row if your winter groundwater runs cold.
Minimum activation flow is 0.5 GPM, so it fires for a hand wash, not just a full shower.
Installing it
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Cabinet: 17.3" W x 27.4" H x 13.2" D
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Weight: 73 lbs
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Water connections: 3/4" NPT cold in, 3/4" NPT hot out
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Gas connection: 3/4" NPT
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Water pressure range: 15-150 PSI
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Power: 120V AC, 60 Hz
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Venting: 2" or 3" PVC, CPVC, polypropylene or stainless steel, intake and exhaust
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Vent clearance: 0" to combustibles
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Altitude: approved to 10,100 feet for both NG or LP gas. See the installation manual for the details.
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Heat exchanger: dual stainless steel, primary and secondary
Ratings and certifications
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UEF: 0.96
- ENERGY STAR® certified
- CSA certified
- NSF Standard 5
- lead free (<0.25%)
- SCAQMD 1146.2 low-NOx (under 20 ppm), the rule that governs Southern California
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AHRI: 206368361
Model details
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Brand: Navien
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Manufacturer part number: NPE-210S2
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UPC: 884954920849
Ships in the manufacturer's carton. Shipping is calculated at checkout by weight, dimensions and destination. Gas connection, venting and condensate disposal must be done by a licensed installer, to the Navien manual and to your local code.