How Does Air Get Into a Hydronic Heating System?

Hydronic heating systems send heated water to baseboard radiators.
Hydronic heating systems send heated water to baseboard radiators. (Image: white radiator image by Ekaterina Sidorenko from

A hydronic heating system uses heated water to heat a house, building or floor. The heated water travels through a system of tubes or pipes that may be located under floors or lead to baseboard radiators.

Video of the Day

How Air Gets In

During fill or back flush hydronic system operations, city or well water enters the system. Water has compressed air in it. As the water flows through the system, the air settles in to high spots. Over time the resulting air pockets reduce the efficiency of the hydronic heating system and create noise in the pipes.

Get Air Our

In order to get trapped air out of the system you will need to circulate cold water through the system, one loop at a time. The water must be cold. Heated water will compress the air and it will not be released as it passes the scoop and vents. Your owner’s manual has instructions on how to release air from your particular hydronic heating system.


Air will always enter your system and build up overtime. The time span between flushing your system with cold water will depend on two things: Make sure that each loop or area has a vent, and if your system does not have a whole house air scoop, get one installed. The implementation of these two preventative measures will keep your system working at peak performance.


Promoted By Zergnet

You May Also Like

Is DIY in your DNA? Become part of our maker community.
Submit Your Work!