.. The newer types have a thermostatic control and will allow whatever speed you need.. they're magic! ;-) Lester On Jan 19, 2009, at 4:00 PM, Billy Zoom wrote: > Don't overlook the fact that if the water moves too fast, it won't > be able > to transfer enough heat to the radiator. That's why you need a block- > off > plate if you run without a thermostat.