Hello,

I am researching flues for my new boiler. I understand that a
conventional flue is the "exhaust" from the boiler and that it has to
draw the air it needs from the room its in, whereas a balanced flue
has an air intake as well as an air outlet built-in.

But I cannot work out what high level and low level flues are. Can
anyone enlighten me?

Thanks,
Stephen.