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When your heating system is supposed to use hot water to heat your home, it can have a problem when air gets in there. The more air that gets in, the worse the system is likely to perform. Removing that air safely may be confusing. Fortunately, it isn’t too difficult to cut this problem down to size and get on with your day.

Airbound Heating Pipes – Not a Good Thing

When your hot water baseboard heating system has air in the lines, it becomes what is known as airbound. This is a noisy problem that can actually disrupt its ability to heat your home, which is a serious problem in a lot of ways. You can typically tell when your system has become airbound by getting too much air in it because of a gurgling or a bubbling during operation. In some cases, with too much air you may find that your heating system can’t heat your home at all because there’s no circulation left.

There are several ways this can happen. One way airbinding can occur is through a small leak in the system. This leak can cause hot water to evaporate out to a tiny extent — so small you likely couldn’t even see it with the naked eye. But over time, even the most miniscule leak can cause enough air to intrude into the system that your heating equipment no longer works as it’s intended to.

Another way air can enter the system is during routine maintenance. Often there is either a blockage of water into the system or the system is closed, meaning that no water enters. If even a small amount of water leaves the pipes during a replacement or other type of service, the system can easily become airbound due to this water loss and the air that fills the void as a result.

The reason why having an airbound system is bad for your heating apparatus and your building as a whole is because heat cannot travel effectively this way. There is not much power in most hot water pumps. They generally use the recently heated water in the system to push other, cooler water through, which keeps hot water moving all the time. When hot water doesn’t circulate, cool water sits in the system and power gets wasted for nothing.


The easiest way to tell if your system has gotten airbound is to see if some of the heating baseboards aren’t getting hot. The radiators and baseboards should all get hot at the same time, and the areas that the baseboards and radiators serve should be warming up when the circulator pump is running. This is a very common problem, and this is the most common reason why there isn’t heat when by all rights there should be.

Fixing the Problem

Hopefully, your system already has air bleeder valves installed high up, since air tends to rise in water. To handle this, you want to turn off the boiler at the service switch. Then you want to check by touch to make sure there are actually sections not heating up even though the boiler is working and the circulator pump is running. After this, you want to connect a hose to the boiler drain to allow air to escape. Finally, if there is a water feeder bypass, you want to open this and let city water flow into the system at enough pressure to force out air in the system. Once the system has enough pressure and the air has bled out, you can close the drain and reactivate the system to heat up.

Don’t feel confident performing these steps yourself?  Seek out a trained technician that can save you time and money by expertly servicing your system.