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Navien NPE-240S NG-LP Indoor-Outdoor Condensing Tankless Water Heater

Original price $1,910.00 - Original price $1,929.95
Original price
$1,910.00 - $1,929.95
Current price $1,910.00


Current stock level: In stock as of

Ship out time: Within 1 business day.
Delivery time: 1 to 3 business days to most addresses

The Navien NPE-S series has the highest efficiency of any tankless water heater at .99EF

That's according to the EPA Energy Star directory. The NPE-240S achieves this feat with advanced condensing technology.

The result is more heat for the same energy, lower energy bills. This amazing efficiency rating allows developers to earn LEED points with any NPE-S unit. The NPE-S series won the 2015 AHR Innovation Award. Go with the winner.

Install indoors or outdoors

The same unit can have interior or exterior installation. See manual for details and required components in addition to the Outdoor Vent Kit.

Energy Star logoUltra Condensing Efficiency

→ Navien's Condensing Technology allows high efficiency heating
→ Significant energy savings over traditional water heaters

Dual Stainless Steel Heat Exchangers

→ Longer life expectancy than copper heat exchangers. More resistant to corrosion
→ Less mineral scaling and deposits

Low-nox-emissionsLow NOx Emissions

→ New metal fiber burner delivers a consistent gas/air mixture
→ Less greenhouse gas emissions and acid rain
→ SCAQMD 1146.2 compliant

2" PVC, CPVC, Polypropylene Venting

→ 2" flue allows you to run the pipe through an existing pipe line
→ Vent up to 60 feet with 2" venting
→ 3" vent can be used up to 150' on standard 2" x 3" adapters

Compatible with Existing 1/2", 3/4", and 1" Gas Lines

→ Many other tankless cannot work with the lower WC pressure with your 1/2" gas line. But with the NPE series, you can use your 1/2" gas lines up to 24 feet. Refer to the installation manual for detailed sizing guidelines.
→ The dual venturi fan and negative pressure gas valve provides compatibility with low gas pressure.

Field Convertible

→ NPE models allow easy conversion from/to natural gas and liquid propane. Navien water heaters are shipped ready for natural gas. Included with each heater, taped to the inside of the case, is the LP orifice.

Less Water Pressure Drop

→ Simple, modular water path minimizes water pressure drops
→ Modular water path design makes maintenance and servicing easier

Navien NPE-180A LP/NG Premium Condensing Tankless Water Heater

Ready Link Cascade System connects multiple units in parallel for larger applications.

Ready-Link Cascading System Features

• Includes built in controls for easily setting adjustments
• Easy wiring between units and easy parent-child configuration for multi-unit systems
• No extra control boards are needed, reducing installation costs
• 16 units can be linked as a single group and cascaded to as many groups as needed
• Cascading provides redundancy for reliable on-demand hot water at any time
• Compact wall-hung design allows a multi-unit system even in confined areas
• Ideal for hotels, schools, beauty shops, restaurants, health centers, hospitals and more

Outdoor vent kit available here.

Front Panel Command Center

• Easy setup
• Self-diagnostics
• User friendly interface
• Convertible display from °F to °C
• Cascade operation status display
• Temperature and water flow rate indicator

Optional Remote Control

• Recirculation timer setting
• Hot water temperature control
• Configurable temperature for cascade systems with external tanks
• Configurable number of initial activating water heaters in cascade systems

asme-logo NSF logo ahri-seal CSA-certified


Important: Navien water heaters are shipped ready for natural gas. Included with each heater, taped to the inside of the case, is the orifice for liquid propane. Consult the Gas Conversion Guide for converting it for use with liquid propane.

  NPE-150S NPE-180S NPE-210S NPE-240S
Heat Capacity NG/LP 18,000-120,000 BTU/h 15,000-150,000 BTU/h 19,900-180,000 BTU/H 19,900-199,900 BTU/H
Energy Factor NG/LP 0.97
Flow Rate at 35°F Rise 6.8 GPM 8.4 GPM 10.1 GPM 11.1 GPM
Flow Rate at 45°F Rise 5.3 GPM 6.5 GPM 7.8 GPM 8.7 GPM
Flow Rate at 67°F Rise 3.2 GPM 4.2 GPM 5.0 GPM 5.6 GPM
Width 17.3"
Height 27.4"
Depth 13.2" 13.2" 13.2"
Weight 55 lbs 67 lbs 75 lbs
Installation Type Indoor or Outdoor Wall-Hung
Venting Type Forced draft direct vent
Ignition Electronic Ignition
Water Pressure 15-150 PSI
Natural Gas Supply Pressure (from source) 3.5"-10.5" WC
Propane Gas Supply Pressure (from source) 8"-13" WC
Natural Gas Manifold Pressure (min to max) -0.04" WC to -0.38" WC -0.04" WC to -0.84" WC -0.04" WC to -0.36" WC -0.04" WC to -0.58" WC
Propane Gas Manifold Pressure (min to max) -0.04" WC to -0.42" WC -0.03" WC to -0.50" WC -0.02" WC to -0.66" WC -0.02" WC to -0.78" WC
Minimum Flow Rate 0.5 GPM
Cold Water Inlet 3/4" NPT
Hot Water Outlet 3/4" NPT
Gas Inlet 3/4" NPT (Suitable with 1/2" rigid gas pipe. Refer to installation manual for sizing criteria.)
Main Supply 120 V AC, 60Hz
Maximum Power Consumption 200W (max 2A), 350W (max 4A) with external pump connected
Casing Cold rolled carbon steel
Heat Exchangers Primary and secondary heat Exchangers: stainless steel
Exhaust 2" or 3" PVC, CPVC, Polypropylene 2" or 3" Special Gas Vent Type BH (Class II, A/B/C)
Intake 2" or 3" PVC, CPVC, Polypropylene 2" or 3" Special Gas Vent Type BH (Class II, A/B/C)
Vent Clearances 0" to Combustibles
Safety Devices APS, Ignition Operation Detector, Water Temperature High Limit Switch, Exhaust Temperature High Limit Sensor, Power Surge Fuse

Box contents

Tankless Water Heater
Installation & Operation Manual
Quick Installation Manual
Wall Mounting Bracket
Four Tapping Screws & Anchors
LP or NG Conversion Kit
Two 2" Vent Termination Caps
Four 2" Wall Flanges
Spare Parts (fuse, etc.)


NPE-A Series and NPE-S Series Brochure

Operation Manual

Installation Manual

Quick Install Guide

Common (multiple unit) Venting Guide

Gas Conversion Guide

FAQ (Frequently Asked Questions)

Q1: I would like to buy this Navien heater to replace another water heater that uses metal vent pipe. I read the manual that describes various PVC products to use for venting. The manual does not state that metal should not be used. Are there any performance issues if I use my metal exhaust vent pipe and not the PVC type pipe?
A1: Yes, the reason for using PVC versus metal is for energy efficiency. Navien recommends using PVC because the NPE and NR heaters are condensing type heaters. Using PVC provides the maximum condensing function. The Navien heaters will run more efficiently with PVC.

Yes, you could use your metal venting instead of PVC; the heater will still work safely. Alternatively, you could install the PVC inside the metal venting, using the metal venting as a chase (like a conduit).

Q2: Which additional parts or accessories needed for installation, not included with the purchased unit itself?
A2: Three part answer:
A2.1. We only sell and ship product that is unopened from the factory, recently manufactured, and includes all items indicated in the manual.
A2.2. Certainly you will need additional hardware items to install this unit. These include water pipe, gas pipe, vent pipe. Obviously they will vary with each installation and home. We do not sell these items.
A2.3. Accessories commonly recommended to include with the installation, and may even be required by some (but not all) local building code:
A2.3.1. Isolation valve kit. This allows the you to shut off the water supply to the tankless unit to service it, without having to shut off the water to the whole house. It also has a port for flushing the unit once per year with anti-scale solution. We have several models available in the blue Related Gadgets tab above.
A2.3.2. Condensate neutralizer cartridge. Click to read about why it might be needed.
A2.3.3. Anti-scale filter

Q3: What is the primary difference between the Navien NPE-A and NPE-S?
A3: The primary difference between the Navien NPE-Advanced series and NPE-Standard series is that the A series has a buffer tank and recirculation pump. The recirc feature is only for homes that have hot water recirculation pipes installed throughout the home. This feature slightly reduces energy efficiency, but only by 2%. The S series is the most efficient gas tankless water heater with an AFUE of 98 to 99%.

Q4: Do the NPE series heaters include a remote control?
A4: No. It is an optional accessory. In the blue Related Gadgets tab above, look for the NR-20DU wired remote control or the NaviLink wireless controller.

Q5: How high can I set the water output temperature?
A5: The NPE A and S series heaters ship from the factory with a maximum set water output temperature of 140°F. However, on the front panel the heater can be set to Commercial Mode which allows for setting a higher output temperature, up to a maximum of 182°F.

Q6: I noticed this unit has 3/4" size gas connections. Is this unit compatible with my 1" gas lines?
A6: Yes, the NPE series can use 1" gas lines. Oversizing gas lines is possible provided the minimum WC (water column) meets the minimum 3.5" and maximum 10.5" WC.

Q7: What are the differences between the NPE series and the NR series heaters?
* Efficiency of the NPE is slightly higher.
* NPE has a front panel display where you can change the temperature as well as see diagnostic messages. On the NR, temperature changes can only be done with the remote control or inside the unit.
* The gas valve on the NPE is negative pressure. On the NR it is positive pressure, which relies on the pressure of the gas line.
* The gas connection on NPE is on the left. On the NR it is on the right.
* NR has 3" exhaust and intake venting. The NPE has 2" exhaust and intake venting. Conversion from 3" to 2" can be done with a common 3" to 2" reducer here: Both the NR and NPE use Schedule 40 PVC.
* NR dimensions: 17.0 W x 28.0 H 14" D
* NPE dimensions: 17.3 W x 27.4" H 11.4" D
* The NPE series has many more improvements over the NR series.

Q8: What is the maximum decibels that this unit emits?
A8: As of February 2019, none of the NPE units have been tested to establish a decibel rating. Navien's engineers are aware of this issue.

Installation Help and Recommendations

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Consumer purchases through the internet or other e-commerce channels shall void Navien's warranty. As with all products we sell, all Navien products we sell are brand new, recently manufactured ("factory fresh"). We guarantee delivery in perfect condition to our customers.

The NAVIEN, KD NAVIEN, ComfortFlow, Ready-Link, and NaviLink trademarks are the property of Navien America, Inc. and/or KyungDong Navien. Navien is not affiliated with and does not sponsor, endorse or warranty/support or products on this website.

Alternate model number spelling: NPE240S