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Condensing Tankless Water Heaters

 

The proven ultra-high-efficiency, eco-friendly, space-saving way to supply endless domestic hot water for homes and businesses.

View All Navien Condensing Products

How Condensing Tankless Water Heaters Work

Ultra high-efficiency tankless water heaters—also known as condensing tankless—use two heat exchangers to supply endless hot water when you turn on a faucet. They use less energy (and money) than traditional water heaters because they don't need to reheat the water over and over.

  1. When a hot water tap is opened, the tankless water heater detects the flow

  2. The flow sensor activates to determine the amount of hot water needed

  3. The igniter activates

  4. The gas control valve opens to supply the correct amount of gas

  5. The fan and venturi activate to provide the correct amount of gas and fuel

  6. The premix burner ignites providing a flame to heat the water

  7. Cold water is pre-heated in the secondary heat exchanger

  8. Pre-heated water passes from the secondary to the primary heat exchanger

  9. The unit determines outgoing set temperature and adjusts the flame to heat the water

  10. Heated water moves to the buffer tank

  11. Desired hot water amount delivered to the faucet

  1. When a hot water tap is opened, the tankless water heater detects the flow

  2. The flow sensor activates to determine the amount of hot water needed

  3. The igniter activates

  4. The gas control valve opens to supply the correct amount of gas

  5. The fan and venturi activate to provide the correct amount of gas and fuel

  6. The premix burner ignites providing a flame to heat the water

  7. Cold water is pre-heated in the secondary heat exchanger

  8. Pre-heated water passes from the secondary to the primary heat exchanger

  9. The unit determines outgoing set temperature and adjusts the flame to heat the water

  10. Heated water moves to the buffer tank

  11. Desired hot water amount delivered to the faucet

What’s the difference between condensing & non-condensing tankless water heaters?

A condensing tankless water heater changes the design of the heat exchanger to take advantage of the water vapor in the exhaust gas. Navien condensing gas tankless water heaters include a second heat exchanger in order to transfer more heat to the water and lower the exhaust gas temperature to a point where the water vapor condenses inside the heat exchanger, increasing the flow rates and overall efficiency of the water heater. Since the exhaust gases are much cooler when they leave the heat exchanger, the exhaust system can be made up of a wider range of materials, such as Polypropylene or PVC. Because the water vapor from the burner is condensing inside the heat exchanger the installation also requires a drain to dispose of the condensation that is produced.

The design of a non-condensing water heater or boiler is to have a heat exchanger that transfers enough heat to get the water temperature where it is needed, but not to lower the exhaust gas temperature to a point where the water vapor condenses. Navien non-condensing gas tankless water heaters are built with a single, or primary, heat exchanger and require exhaust systems that will tolerate higher temperatures.

Are condensing tankless water heaters better than non-condensing? 

It depends, condensing tankless water heaters offer higher flow rates, an efficiency rating of up to 0.96 UEF, and the lower exhaust temperatures allow them to use more cost-effective installation materials such as polypropylene or PVC. Condensing units do need to drain out acidic condensate, so they will require a condensate drain and potentially a condensate neutralizer to neutralize the pH of the condensate before it is drained.

Non-condensing tankless water heaters are smaller in design and don’t have to drain acidic condensate, which make them more flexible when it comes to installation location. With an efficiency rating of 0.81 UEF, it is still much more efficient than a standard tank type water heater.

Condensing vs Non-Condensing 
Tankless Water Heaters

  Condensing Non-Condensing
Initial cost Usually higher than comparable non-condensing Usually lower than comparable condensing
Long term operating cost Lower than typical non-condensing tankless and storage tank system Could be higher than condensing but lower than storage tank systems
Efficiency Ultra-high Efficiency (UEF up to .96) High Efficiency (UEF > .80)
Maintenance requirement Annual service recommended Minimal
Venting PVC acceptable 3" x 5" metal concentric required
Installation Location Indoor or Outdoor Choice of interior or exterior
Durability Stainless steel heat exchanger extend service life Stainless steel heat exchanger extend service life
Dimensions Slightly larger than non-condensing, about 70-80% smaller than tank system Slightly smaller than condensing, 80% smaller than tank system

Navien Condensing Tankless Water Heaters

The Navien NPE-2 series is a line of high-efficiency condensing tankless water heaters featuring a user-friendly control panel. These tankless water heaters can be installed indoors or outdoors, for residential or commercial use.

Navien NPE-2 High Efficiency Condensing Tankless Water Heaters

NPE-A2 Series

Advanced condensing tankless water heaters featuring Navien’s patented ComfortFlow® system.

NPE-180A2
Max Input: 150,000 BTU/h
Indoor or outdoor wall-hung
Residential/Commercial

ComfortFlow® Technology

NPE-180A2
View model
NPE-180A2
NPE-210A2
Max Input: 180,000 BTU/h
Indoor or outdoor wall-hung
Residential/Commercial

ComfortFlow® Technology

NPE-210A2
View model
NPE-210A2
NPE-240A2
Max Input: 199,900 BTU/h
Indoor or outdoor wall-hung
Residential/Commercial

ComfortFlow® Technology

NPE-240A2
View model
NPE-240A2

NPE-S2 Series

Navien’s standard ultra high-efficiency condensing tankless water heaters.

NPE-150S2
Max Input: 120,000 BTU/h
Indoor or outdoor wall-hung
Residential/Commercial

ComfortFlow® Technology

NPE-150S2
View model
NPE-150S2
NPE-180S2
Max Input: 150,000 BTU/h
Indoor or outdoor wall-hung
Residential/Commercial

ComfortFlow® Technology

NPE-180S2
View model
NPE-180S2
NPE-210S2
Max Input: 180,000 BTU/h
Indoor or outdoor wall-hung
Residential/Commercial

ComfortFlow® Technology

NPE-210S2
View model
NPE-210S2
NPE-240S2
Max Input: 199,900 BTU/h
Indoor or outdoor wall-hung
Residential/Commercial

ComfortFlow® Technology

NPE-240S2
View model
NPE-240S2

Navien NPE-2 Series condensing tankless water heaters deliver an endless supply of hot water for any size home.

Besides providing hot water where and when it’s needed, the NPE-2 Series offer homeowners the following benefits:

  • Much more energy efficient than old fashioned tank systems
  • Ultra high energy efficiency —
    up to 0.96 UEF
  • Backed by the industry's strongest warranty – 15 years on heat exchangers
  • Energy Star certified
  • Takes about 80% less space than old fashioned tank heaters
  • Longer lasting than tank heaters
  • Easy to use control panel
  • Elegant, clean appearance
  • Improves resale value
  • Ideal for replacements or new construction

Benefits of Navien Condensing Tankless Water Heaters

The Ultimate Endless Hot Water Solution For Your Home

  • Npe-2-feature-heatexch

    Durable, Long-Lasting Construction

    Navien NPE-2 condensing tankless water heaters use durable dual stainless steel heat exchangers.

  • Nfc-feature-flat-plate

    Eco-Friendly

    Condensing technology reduces energy consumption and greenhouse gas emissions.

  • Npe-2-feature-navilink

    Control from Your Phone

    Optional NaviLink™ Wi-Fi control system gives you access to your Navien systems from anywhere in the world.

  • Feature-images

    Multiple venting options

    For homes with extra high demand, NPE-2 Series units can be cascaded without an external control.

  • Npe-2-feature-hotbutton

    On-demand Recirculation

    HotButton on-demand recirculation option with built-in controller.

  • Npe-2-feature-h2air

    Optional Forced Air Systems

    H2Air combination space heating and domestic hot water supply optional for NPE-A2 models.

The ultimate in energy efficiency

Navien condensing technology provides up to 0.96 UEF. These extremely efficient and eco-friendly units provide extra energy savings over traditional tank and non-condensing tankless water heaters.

Operating Cost

Navien Tankless
179.0 therms
$195*
Other Tankless
228 therms
$249
50 Gallon Tank
293 therms
$319
* Based on Energy Guide cost estimates using $1.09 per therm of natural gas. Cost is in US dollars.
Npe2-large-bottom

Protect the environment
as you add value

 
Navien condensing stainless steel heat exchangers recover extra heat that would be lost in non-condensing boilers. The result is a reduction in energy consumption, lower CO2 emissions and low exhaust temperatures allowing the use of less expensive venting materials such as Schedule 40 PVC.

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