Main Boiler Components

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Main Boiler Components

8 March 2023
 Categories: , Blog

A boiler uses hot water to provide heat throughout your home. It generates "clean heat" and operates more efficiently than furnaces, but boilers also have a lot of different components that can go out. When you need boiler repair, consider replacing one of the components before placing the entire unit. 


The burner starts the heating process by creating ideal conditions for ignition. A valve opens to allow gas to the burner, where it will combine with oxygen and ignite in the combustion box. If the burner goes out, the heat exchanger and water will never get hot. 

Heat Exchanger 

The heat exchanger indirectly transfers heat from hot coils to the water inside the boiler tank when it drops below the temperature setting. The heat exchanger receives heat directly from the burner and combustion box. 

Your boiler's heat exchanger is one of the most expensive components, so if the heat exchanger breaks, most homeowners will be better off getting a new boiler. 


Boilers transport heat through radiators around the house in a similar fashion to the way furnaces transport heat through ducts. Radiators provide more even heat. Additionally, radiators don't accumulate dust and debris the way ducts do, contributing to better indoor air quality (IAQ). 

The radiators last a long time, but if you ever notice a radiator leaking, the radiator needs to be replaced (not the boiler). 

Recirculation Pump

Recirculation pumps transport hot water through the radiator system using an electric water pump. The pump keeps water constantly flowing so that users can access heat quickly when they need it. If the recirculation pump breaks down, you will notice that it takes longer for certain areas of the house to get heat. When you replace the pump, the system should function normally again. 

Expansion Tank 

An expansion tank protects the boiler from excess pressure. Heat expands, so when the water inside the boiler gets hot, it expands. Suddenly, the 20-gallon boiler must hold 21 gallons of water. The pressure can weaken the boiler tank material if it doesn't have a place to go. That's where the expansion tank comes in. The expansion tank receives the extra water and pressure that is created through the heating process until water escapes the boiler, making room for the extra water in the expansion tank. 

When you need boiler repair, you may need to repair one of the numerous components making the device work. Contact a heating repair contractor for assistance or for more info.