My house has monoflow hot water heat. Since buying the house we have made a couple changes, nothing major to heating system. The problem I have is that I cannot get the air out of the system. I have gotten it to a point that you could not hear any air flowing in the pipes but then a day or two later its back. My wife thinks I am nuts, spending countless hours bleeding and searching for air/water leaks to eliminate this problem.

A friend of mine said that this is a common problem with this type of system, and if I wanted to keep it this way that I need to make a couple changes. These being to install an "air scoop" ( to remove the air in the main loop)and a new expansion tank (current one is the original bladderless type).

Any insight and advise would be appreciated. Thanks, Ed