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Boilers 101: How Hydronic Heating Systems Work

Boilers burn fuel (natural gas or LP) to heat water as part of a closed hydronic heating system. This video explains how Navien high-efficiency condensing heating boilers work, and features of the different boiler types available.

Learn More About Navien Boilers

Navien’s advanced burner technology offers the highest energy efficiency in the industry - up to 95% AFUE. Learn more about the benefits of Navien residential boilers.

Navien’s NHB series boilers are compact, easy to install, and include our advanced burner system.

Navien’s NFB-H series boilers are the most advanced condensing fire tube boilers available today, with capacity for homes of all sizes.

What's a Boiler

A boiler is the Heart of your Hydronic Heating System 
In the simplest terms, a boiler is a vessel that heats water, which is then pumped through radiators, baseboard heaters or other components of a closed hydronic heating system.


Boiler Applications

Most boilers are only used for hydronic space heating.

Boilers that are used for both space heating and domestic hot water production are called combi-boilers.


Navien boiler external connections 
Boilers are fairly straightforward – you’ll see connections for combustion air, exhaust, boiler return, boiler supply, gas and condensate drainage


Boilers internal components
On the inside, the critical components include the heat exchanger, controls, fan, burner, gas valve, control wiring and internal piping.


How a Navien Boiler Works 
Similar to a forced-air heating system, your home’s thermostat senses a drop in temperature and signals the boiler to turn on.

Using natural gas or propane, the boiler heats the water in the system. This heated water then flows through your house via radiators, hydronic baseboards or in-floor radiant heating systems to warm your home.

As the system heats the home/space, the water cools and returns to the boiler to be reheated.

This process continues until your home reaches the set temperature and your thermostat calls for the boiler to turn off. Your boiler remains in this standby mode until the thermostat calls again for heat.


Selecting a Navien boiler type  
When selecting the right boiler for your home, there are several factors that need to be taken into consideration, including space heating capacity requirements, efficiency, fuel type, heating type, physical size, and boiler output.

Navien requires that every unit sizing and installation be performed by a qualified contractor and conform to the installation and operation manual included with the unit.


Navien offers a wide range of high efficiency, high capacity home heating boilers. Navien has 6 residential boiler models that are available from 55,000 BTU/h up to 199,900 BTU/h.


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