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April 17, 2024

Different Types of Hydronic Heating

Hydronic heating uses hot water to heat an indoor space, and there are several different types of hydronic heating systems, including:

  • Boilers
  • Combi-boilers
  • Hydro-furnaces
  • Hydronic heat pumps
  • Hydronic air handlers

Let’s take a closer look at how each type of hydronic heating system works, to understand what makes them different.


Boilers burn fuel (natural gas or LP) to heat water, which then heats your home as part of a closed hydronic heating system. The heated water can be pumped through radiators, baseboard heaters, hydronic radiant floor systems, or other components.


Combi-boilers provide hydronic heating the same way that boilers do, and they also provide hot water for faucets, dishwashers, showers and washing machines.


Hydro-furnaces heat water by burning fuel (natural gas or LP) in a sealed combustion heat exchanger, completely isolated from the airstream. The heated water is then circulated through a hydronic heat exchanger inside the furnace. A high-efficiency variable speed ECM blower gently transfers the heat into the air and quietly distributes it through the home. Built-in controls constantly monitor and dynamically adjust water temperature, water flow and air temperature as necessary to optimize comfort and efficiency.

Hydro-furnaces heat homes using forced-air ducting, but because water is used to heat the air (instead of heating the air directly, like a conventional furnace) there’s less of an impact on the conditioned air humidity level. This minimizes the need for add-on humidifiers and the associated consumables, creating a much more comfortable living environment.

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Hydronic Heat Pumps

Hydronic heat pumps absorb thermal energy from outdoors by using refrigerant, which allows them to extract heat from outside air, even on cold days.

After absorbing heat, the refrigerant is compressed, which increases the temperature. Heat from the compressed refrigerant is transferred to a heat exchanger coil which then heats water. The heated water is pumped through a closed hydronic heating system such as radiators, baseboard heaters, etc.

Hydro-Furnace Compatible with Heat Pumps

Navien’s NPF hydro-furnace is dual-fuel compatible (gas or electric heating with heat pump) when paired with any AHRI-matched heat pump. The NPF not only enhances the efficiency of heat pump systems, it provides independent airflow settings to maximize year-round comfort.

Hydronic Air Handlers

Hydronic air handlers work with a boiler or water heater to heat your home. The boiler or water heater heats water, which is then circulated through a water-to-air coil inside the hydronic air handler. The heat from the water is transferred to the air when air it circulates through the heat exchanger, and the heated air is then circulated throughout the home.

Choosing a Hydronic Heating System for Your Home

Whether your home is heated using a closed hydronic heating system (such as radiators/baseboards) or forced air, Navien offers high-efficiency hydronic heating solutions with superior reliability and unmatched performance:

  • Navien condensing heating boilers have industry-leading turndown ratios and heating capacity for homes of all sizes in a compact, wall-hung unit perfect for tight spaces and retrofits.
  • Navien combi-boilers provide whole-home heating along with endless hot water on demand, and take up significantly less space than a floor-standing boiler and tank water heater.
  • Navien’s hydro-furnace provides consistent, comfortable forced-air heating with minimal energy consumption, minimal sound and easy, intuitive controls.
  • Navien’s H2Air accessory for our NPE-A2 Series tankless water heaters provides high-efficiency space heating and endless domestic hot water by integrating the tankless water heater with a hydronic air handler.

Ready to get started? Find a certified Navien installer in your area.

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