Navien Tankless Water Heater and Boiler Comparison
Every Navien model we stock, side by side, with the numbers you need to size a job: gas input, UEF, and domestic hot water flow at three temperature rises. Figures are taken from Navien’s published specifications. Click any model for its full spec sheet, submittal and installation manual.
How to read the flow-rate columns
A tankless heater does not have a single GPM rating. Its output depends on how far it has to raise the incoming water temperature. The colder your supply water, the fewer gallons per minute the same unit delivers.
- Temperature rise = your target output temperature minus the incoming ground water temperature.
- Add up the flow of the fixtures you expect to run at the same time, then read the column that matches your temperature rise.
- Northern installations generally size against the higher rise columns; warmer regions can size against the lower ones.
Tankless water heaters
NPE-2 / NPE-A2 — condensing tankless
| Model | Max input | UEF | GPM @35°F | GPM @45°F | GPM @67°F | Min. flow | Dimensions (W×H×D) |
|---|---|---|---|---|---|---|---|
| NPE-240S2-NG/LP | 199,900 BTU/h | 0.96 | 11.2 GPM | 8.7 GPM | 5.8 GPM | 0.5 GPM | 17.3" W x 27.4" H x 13.2" D |
| NPE-240A2 | 199,900 BTU/h | 0.95 | 11.2 GPM | 8.7 GPM | 5.6 GPM | 0.5 GPM, < 0.01 GPM option* | 17.3" W x 27.4" H x 13.2" D |
| NPE-210S2-NG/LP | 180,000 BTU/h | 0.96 | 10.1 GPM | 7.8 GPM | 5.3 GPM | 0.5 GPM | 17.3" W x 27.4" H x 13.2" D |
| NPE-210A2 | 180,000 BTU/h | 0.95 | 10.1 GPM | 7.8 GPM | 5.1 GPM | 0.5 GPM, < 0.01 GPM option* | 17.3" W x 27.4" H x 13.2" D |
| NPE-180S2-NG/LP | 150,000 BTU/h | 0.96 | 8.4 GPM | 6.5 GPM | 4.3 GPM | 0.5 GPM | 17.3" W x 27.4" H x 13.2" D |
| NPE-180A2 | 150,000 BTU/h | 0.95 | 8.4 GPM | 6.5 GPM | 4.3 GPM | 0.5 GPM, < 0.01 GPM option* | 17.3" W x 27.4" H x 13.2" D |
| NPE-150S2-NG/LP | 120,000 BTU/h | 0.93 | 6.8 GPM | 5.3 GPM | 3.4 GPM | 0.5 GPM | 17.3" W x 27.4" H x 13.2" D |
NHW — compact tankless
| Model | Max input | UEF | GPM @35°F | GPM @45°F | GPM @67°F | Min. flow | Dimensions (W×H×D) |
|---|---|---|---|---|---|---|---|
| NHW700-199SU-NG | 199,900 BTU/h | 0.81 | 9.5 GPM | 7.4 GPM | 5.4 GPM | 0.3 GPM | 14.0" W x 23.0" H x 9.3" D |
| NHW700-199SU-LP | 199,900 BTU/h | 0.81 | 9.5 GPM | 7.4 GPM | 5.4 GPM | 0.3 GPM | 14.0" W x 23.0" H x 9.3" D |
| NHW700-199AI-NG | 199,900 BTU/h | 0.81 | 9.5 GPM | 7.4 GPM | 5 GPM | 0.4 GPM, < 0.01 GPM option* | 17.3" W x 26.5" H x 10.3" D |
| NHW700-180SU-NG | 180,000 BTU/h | 0.81 | 8.5 GPM | 6.6 GPM | 4.8 GPM | 0.3 GPM | 14.0" W x 23.0" H x 9.3" D |
| NHW700-180AI-NG | 180,000 BTU/h | 0.81 | 8.5 GPM | 6.6 GPM | 4.5 GPM | 0.4 GPM, < 0.01 GPM option* | 17.3" W x 26.5" H x 10.3" D |
| NHW700-160SU-NG | 160,000 BTU/h | 0.81 | 7.6 GPM | 5.9 GPM | 4.1 GPM | 0.3 GPM | 14.0" W x 23.0" H x 9.3" D |
NPN — non-condensing tankless
| Model | Max input | UEF | GPM @35°F | GPM @45°F | GPM @67°F | Min. flow | Dimensions (W×H×D) |
|---|---|---|---|---|---|---|---|
| NPN-180U-LP | 180,000 BTU/h | 0.81 | 8.5 GPM | 6.6 GPM | 4.6 GPM | 0.5 GPM | 14.0" W x 23.0" H x 9.3" D |
| NPN-180E-LP | 180,000 BTU/h | 0.81 | 8.5 GPM | 6.6 GPM | 4.6 GPM | 0.5 GPM | 14.0" W x 23.0" H x 9.3" D |
| NPN-160U-LP | 160,000 BTU/h | 0.81 | 7.6 GPM | 5.9 GPM | 4 GPM | 0.5 GPM | 14.0" W x 23.0" H x 9.3" D |
Boilers and combi boilers
Combi units serve space heating and domestic hot water from one appliance. Heating-only boilers require a separate water heater. Model numbers carry the ratings: NCB-240/110H is 240,000 BTU/h domestic hot water and 110,000 BTU/h space heating.
| Model | Type | Heating input | DHW input | Thermal eff. | Dimensions (W×H×D) | Weight | Gas inlet |
|---|---|---|---|---|---|---|---|
| NCB-240/110H | Combi | 110,000 BTU/h | 199,900 BTU/h | — | 17.3" W x 29.3" H x 12.8" D | 96 lbs | — |
| NCB-240/110H-RAL | Combi | 110,000 BTU/h | 199,900 BTU/h | — | 17.3" W x 29.3" H x 12.8" D | 96 lbs | — |
| NFC-250/175H | Combi | 175,000 BTU/h | 210,000 BTU/h | — | 17.3" W x 33.5" H x 17.3" D | 141 lbs | — |
| NFC-250/200H | Combi | 199,900 BTU/h | 210,000 BTU/h | — | 17.3" W x 33.5" H x 17.3" D | 141 lbs | — |
| NPF700-060U3BH | Combi + buffer | 60,000 BTU/h | — | — | 17.5" W x 34.5" H x 31.0" D | 145 lbs | 1/2" NPT |
| NPF700-100H5CH | Combi + buffer | 100,000 BTU/h | — | — | 34.5" W x 21.0" H x 31.0" D | 167.6 lbs | 1/2" NPT |
| NPF700-100U5CH | Combi + buffer | 100,000 BTU/h | — | — | 21.0" W x 34.5" H x 31.0" D | 167.6 lbs | 1/2" NPT |
| NHB-110H | Heating only | 110,000 BTU/h | — | — | 17.3" W x 23.8" H x 12.8" D | 80 lbs | 3/4" NPT (male) |
| NHB-150H | Heating only | 150,000 BTU/h | — | — | 17.3" W x 23.8" H x 12.8" D | 80 lbs | 3/4" NPT (male) |
| NHB-55H | Heating only | 55,000 BTU/h | — | — | 17.3" W x 23.8" H x 12.8" D | 73 lbs | 3/4" NPT (male) |
| NHB-80H | Heating only | 80,000 BTU/h | — | — | 17.3" W x 23.8" H x 12.8" D | 73 lbs | 3/4" NPT (male) |
| NFB-175H | Heating only | 175,000 BTU/h | — | — | 17.3" W x 27.6" H x 17.3" D | 121 lbs | 3/4" NPT |
| NFB-200H | Heating only | 200,000 BTU/h | — | — | 17.3" W x 27.6" H x 17.3" D | 121 lbs | 3/4" NPT |
| NFB-301C | Heating only | 301,000 BTU/h | — | 97.5% | 25.1" W x 32.8" H x 22.3" D | 243 lbs | 3/4" NPT |
| NFB-399C | Heating only | 399,000 BTU/h | — | 97.5% | 25.1" W x 32.8" H x 22.3" D | 278 lbs | 3/4" NPT |
Notes on selection
- NPE-A2 vs NPE-S2 — both share the same gas input and flow rates. The A2 adds Navien’s built-in ComfortFlow recirculation system with an internal buffer tank and pump; the S2 does not, and is the lower-cost option when an external recirculation loop is already planned.
- Condensing vs non-condensing — the NPE series runs at UEF 0.93 to 0.96 and vents in PVC. The NPN and NHW series run at UEF 0.81 and carry different venting requirements. Check the exhaust material listed on each product page before quoting a vent run.
- Gas supply — every model in this table lists its required natural gas and propane supply pressure on its product page. Confirm the meter and line can carry the input before specifying.
Prices and availability are shown on each product page. For model-specific documentation — specification sheets, submittals, installation and service manuals — open the product and expand the Documents section.