<a href=showthread.php?s=&postid=7059719#post7059719 target=_blank>Originally posted</a> by phlipper84
As to the Velocity T4, I have a theory, and trust me it is only a theory. The heat problem has not really been an issue for me. The issue has been pump failure. Unlike other pumps, the Velocity's seem prone to calcium build up on the impeller and the cup that is on the inside (don't know what to call it). Anyhow, not knowing of this problem, the pumps stopped functioning. Upon disassembly I found the calcium that needed to be chipped off with a knife. And even when it was off, the motor had seized. Here comes the theory. As this obviously took time to develop, perhaps the added friction causes the motor to generate more heat as it strains to turn the impeller. This pump is truly the quietest I have run, but the failure rate makes them totally unacceptable to me.