Ok, well, my educated guess is that this is a fan that will have the free-air flow rating of 2010 cfm drop pretty badly when put in front of or behind a rad. There are a few with that type of design that flow OK but most do not. Being an inexpensive fan is another indicator that it is likely not very good; the good ones of that design cost much more. And 2010 cfm free flow is not a whole lot to start with anyway. This would explain the problem you are having.
