Guides / Water heaters · Updated
Navien NPE-240A2: flow, gas line and venting
From Navien's specification sheet and installation manual, read November 2026.
Short answer
The NPE-240A2 burns up to 199,900 Btu an hour and makes 11.2 gpm at a 35°F rise, 8.7 at 45°F and 5.6 at 67°F. It vents in 2 in PVC up to 75 ft, runs on 1/2 in rigid gas pipe up to 24 ft, and plugs into 120 V.
For the whole house, with sinks, a dishwasher and a washer, use the tankless sizing calculator.
Flow by temperature rise
| 35°F rise | 11.2 gpm |
|---|---|
| 45°F rise | 8.7 gpm |
| 67°F rise | 5.6 gpm |
Each figure is about 392 gpm·°F, so divide 392 by your rise: winter water at 45°F heated to 105°F is a 60°F rise, about 6.5 gpm.
Specs
| Gas input | 13,300 to 199,900 Btu/h |
|---|---|
| Size | 17.3 in wide × 27.4 in high × 13.2 in deep |
| Weight | 77 lb |
| Gas | 3/4 in gas inlet. Navien: "Compatible with 1/2" gas pipe up to 24 ft equivalent length" (rigid pipe; not 1/2 in corrugated connectors). |
| Venting | 2 in vent up to 75 ft with up to 6 elbows (each 90° counts 8 ft); 3 in up to 150 ft with up to 8 elbows (each 90° counts 5 ft). PVC, CPVC, polypropylene or stainless; 0 in to combustibles. |
| Electrical | 120 V; 200 W (2 A max), 350 W (4 A) with an external pump |
| Starts at | 0.5 gpm (or under 0.01 gpm in ComfortFlow recirculation mode) |
| UEF | 0.95 |
| Warranty | 15-year heat exchanger, 5-year parts, 1-year labor (residential); 5 and 3 years with uncontrolled recirculation |