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April 17, 2024

Hydronic Air Handler vs Hydro-Furnace

Navien’s new NPF Hydro-Furnace is an innovative leap in hydronic forced-air heating, while hydronic air handlers have been around for decades. Understanding the similarities and differences between these two forms of hydronic forced-air heating will help you decide which technology is best for your project.


  • Hydronic air handlers and hydro-furnaces both use hot water and a water-to-air heat exchanger to heat the conditioned airstream.
  • Both systems use forced air (blower fans) to distribute heated air throughout the home.
  • Both systems are available in upflow or horizontal orientations for installation flexibility.
  • Both systems can be paired with a heat pump or air conditioning system for year round comfort.


  • Hydronic air handlers rely on a separate tankless water heater, boiler or combi-boiler to supply hot water. A hydro-furnace is connected to water and gas lines directly. It's one piece of equipment that heats and circulates the water, and has an integral high-efficiency variable speed ECM blower and hydronic water-to-air coil to transfer the heat energy into the air and distribute it throughout the home.
  • A hydronic air handler won’t be able to provide space heating while the connected water heater or boiler is undergoing maintenance/repairs. A hydro-furnace is able to provide space heating regardless of the status of a separate water heater/boiler.
  • Our hydro-furnace has an advanced ECM motor for greater efficiency, quieter operation and a longer service life compared to PSC motors commonly used in hydronic air handlers.

What is a hydronic air handler?

A hydronic air handler consists of a coil, pump, blower and controls contained in a cabinet connected to a building's air ducts. A hydronic air handler is a specialized HVAC product that gets its heat by connecting to a separate tankless water heater, condensing boiler or combi-boiler.

When the thermostat calls for heat, the hydronic air handler’s pump moves hot water from the separate water heater or boiler through the hydronic air coil. Air blows over the coil and absorbs heat, then distributes it through the ducts.

diagram showing how a hydronic air handler works, with water and air flows indicated

Navien’s H2Air accessory lets you connect our NPE-A2 tankless water heater to a hydronic air handler so you can enjoy endless hot water and comfortable home heating.

What is a hydro-furnace?

The NPF hydro-furnace contains all the components in one cabinet: a combustion heat exchanger to burn gas (at a 97% efficiency level) to heat the water, a hydronic coil to transfer the heat energy into the air, a circulating pump to move the water between heat exchangers, controls, and an ECM variable speed blower to circulate the air over the hydronic coil and distribute that heated air through the home.

Our NPF hydro furnace burns gas to heat water in a sealed combustion heat exchanger out of the airstream. The heated water is then pumped through the furnace’s hydronic heat exchanger, where the heat is transferred from the water to the conditioned airstream. The heated air is then quietly and evenly circulated through ductwork and the home.

diagram showing how a hydronic forced air furnace works, with hydronic coil and heat exchanger labeled

Learn more about Navien’s NPF Series hydro-furnace, or find an installer today.

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