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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.

woman smiling while using a handheld shower head

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

running showerhead with the words condensing or non-condensing

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

Condensing gas tankless water heaters include a second heat exchanger which uses heat from the exhaust gas to preheat incoming cold water. This technology increases the hot water flow rate, improves energy efficiency, and lowers the exhaust gas temperature. 


Cooler exhaust means you have a wider range of venting material options, including PVC and polypropylene. Because water vapor condenses inside the unit as the exhaust gas cools, condensing tankless water heaters require a drain (and potentially a pH neutralizer) to dispose of the acidic condensation water.


Non-condensing tankless water heaters have a single heat exchanger and do not recycle heat from the exhaust gas. Because the exhaust gas is very hot when it leaves the unit, metal concentric venting is required. Because water vapor does not condense inside the unit, there is no drain required for installation.

washing hands in sink with the words condensing or non-condensing

Are condensing tankless water heaters better than non-condensing? 

It depends on your priorities: 


Condensing tankless water heaters offer higher flow rates, an efficiency rating of up to 0.96 UEF, and allow the use of more cost-effective venting materials such as polypropylene or PVC. But condensing units require a drain, which can limit your installation location options.


Non-condensing tankless water heaters are smaller than comparable condensing models and offer more flexibility for installation since they don't need a drain. Non-condensing units have an efficiency rating of 0.81 UEF, which is still far more efficient than tank-style water heaters.

Condensing Water Heater FAQ'S

As water is heated, the burner creates hot exhaust gas. Condensing tankless water heaters use the heat from exhaust gas to preheat cold water, making them very energy efficient. As it cools, the exhaust gas condenses and turns into water vapor which eventually flow out to the drain.

Yes, condensing tankless water heaters need a drain for the condensation water that forms in the secondary heat exchanger.

Condensing tankless water heaters can be vented through a wall or the roof, up to 75 feet with 2” vent pipe. Because condensing tankless water heaters have relatively cool exhaust gas, you can use 2” PVC or rigid/flexible polypropylene venting. Condensing tankless water heaters cannot share venting with other appliances, and cannot be vented through a chimney.

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.

ComfortFlow® includes a buffer tank, recirculation pump and fine-tuned controls which resolve the “cold water sandwich” effect and flow rate issues common in other tankless water heaters.

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

ComfortFlow® Technology

Navien NPE-180A2 advanced high efficiency condensing tankless water heater
View model
NPE-180A2
NPE-210A2
Max Input: 180,000 BTU/h
Indoor or outdoor wall-hung
Residential/Commercial

ComfortFlow® Technology

Navien NPE-210A2 advanced high efficiency condensing tankless water heater
View model
NPE-210A2
NPE-240A2
Max Input: 199,900 BTU/h
Indoor or outdoor wall-hung
Residential/Commercial

ComfortFlow® Technology

Navien NPE-240A2 advanced high efficiency condensing tankless water heater
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

Navien NPE-150S2 standard high efficiency condensing tankless water heater
View model
NPE-150S2
NPE-180S2
Max Input: 150,000 BTU/h
Indoor or outdoor wall-hung
Residential/Commercial

ComfortFlow® Technology

Navien NPE-180S2 standard high efficiency condensing tankless water heater
View model
NPE-180S2
NPE-210S2
Max Input: 180,000 BTU/h
Indoor or outdoor wall-hung
Residential/Commercial

ComfortFlow® Technology

Navien NPE-210S2 standard high efficiency condensing tankless water heater
View model
NPE-210S2
NPE-240S2
Max Input: 199,900 BTU/h
Indoor or outdoor wall-hung
Residential/Commercial

ComfortFlow® Technology

Navien NPE-240S2 standard high efficiency condensing tankless water heater
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

  • dual stainless steel heat exchangers

    Durable, Long-Lasting Construction

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

  • stainless steel flat plate secondary heat exchanger

    Eco-Friendly

    Condensing technology reduces energy consumption and greenhouse gas emissions.

  •  person using NaviLink app at airport to control tankless water heater via Wi-Fi

    Control from Your Phone

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

  • four condensing tankless water heaters with common venting

    Multiple venting options

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

  • illustration of condensing tankless water heater using recirculation to provide hot water to shower

    On-demand Recirculation

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

  • illustration of condensing tankless water heater providing space heating and domestic hot water

    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.
Navien NPE-2 condensing tankless water heater displaying 120°F

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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