[ondaedg]

I have read that article. BillA does do alot of work in this area. Great info. The problem is that increasing the flow rate lowered the radiator's performance less than 10% in some cases and increased their performance in others which leads me to believe that perhaps this isn't really an issue that should be addressed when selecting a pump. So in my opinion, opting for the more powerful Eheim (that is the original topic right?) is not going to hurt his performance to the point that he should have gone with the smaller pump. Furthermore, it gives him headroom to add more blocks for other components (if he feels like gettin crazy) . Technically, you are right that it did in some instances lower the radiator's btu/hr rating. I just think that the difference is so minimal, that it really should be a non issue. Feel free to argue otherwise. =]