Navien NPE-240A2 ComfortFlow® High Efficiency Condensing Tankless Water Heater, 199,900 BTU, Indoor/Outdoor, NG/LP Convertible

The Navien NPE-240A2 is a condensing gas tankless water heater with a maximum input of 199,900 BTU/h and a 0.95 UEF. It delivers 8.7 GPM at a 45°F temperature rise and 5.6 GPM at a 67°F rise, and modulates down to 13,300 BTU/h. The A2 version has Navien's ComfortFlow recirculation pump and buffer tank built in; the NPE-240S2 has the same input without the pump and buffer tank. It mounts indoors or outdoors, runs on natural gas or propane, and vents in 2" or 3" pipe.

Key Features

• Modulating input from 13,300 to 199,900 BTU/h on natural gas or propane
• 0.95 UEF; ENERGY STAR certified
• ComfortFlow built-in recirculation pump and buffer tank
• Hot water flow: 11.2 GPM at a 35°F rise, 8.7 GPM at 45°F and 5.6 GPM at 67°F
• Minimum activation flow 0.5 GPM; Navien also lists a < 0.01 GPM option
• Primary and secondary stainless steel heat exchangers
• Cabinet 17.3" W x 27.4" H x 13.2" D, 77 lbs

Applications

• Whole-house domestic hot water; size on the 67°F figure where incoming water is cold
• Homes that want hot water recirculation without adding an external pump
• Replacing a storage tank water heater where a gas line, vent route and condensate drain are available
• Residential and commercial hot water loads within the rated flow

Before You Order

• Gas type: listed for natural gas and propane (NG/LP convertible). Confirm which gas the unit is set up for, and have any conversion done by a licensed installer following the Navien manual.
• Gas line: 3/4" gas connection. The meter and line must supply the full 199,900 BTU/h; supply pressure is 3.5" to 10.5" WC on natural gas and 8" to 13" WC on propane.
• Venting: 2" or 3" PVC, CPVC, approved polypropylene or stainless steel for intake and exhaust, 0" clearance to combustibles.
• Electrical: 120V AC, 60 Hz supply at the unit.
• Water: 3/4" cold inlet and 3/4" hot outlet; water pressure 15 to 150 PSI.
• Condensate: this is a condensing appliance and produces acidic condensate. Plan a drain line to a suitable drain, with a neutralizer where local code requires one.
• Altitude: approved to 10,100 ft on natural gas or propane; see the installation manual for high-altitude settings.

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-240A2 delivers:

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.

With a Navien recirculation setup this unit also supports the low-flow activation option, down to under 0.01 GPM.

About ComfortFlow®: the pump and the buffer tank are inside the unit, not bolted on. That is what kills the cold-water sandwich when someone turns the shower off and back on, and it lets you run recirculation on a dedicated return line or on a crossover valve at the far fixture.

Installing it

• Cabinet: 17.3" W x 27.4" H x 13.2" D
• Weight: 77 lbs
• Water connections: 3/4" cold in, 3/4" hot out
• Gas connection: 3/4"
• Water pressure range: 15-150 PSI
• Power: 120V AC, 60 Hz
• Venting: 2" or 3" PVC, CPVC, polypropylene or stainless steel, intake and exhaust
• Vent clearance: 0" to combustibles
• Altitude: approved to 10,100 feet for both NG or LP gas. See the installation manual for the details.
• Heat exchanger: dual stainless steel, primary and secondary

Ratings and certifications

• UEF: 0.95
• 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
• AHRI: 206368359

Model details

• Brand: Navien
• Manufacturer part number: NPE-240A2
• UPC: 884954920870

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.

Questions about fit or compatibility? Ask our team. We usually reply within one business day.