Walter is right, these are great pumps at high temps in a closed system. If you are trying to pump any liquid near its boiling point in an open system like brewing, however, your plumbing needs to be proper. Are you having problems only when the kettle is being heated and at 190? It is likely that spot boiling is causing small bubbles to be sucked into the inlet of the pump, which is at a partial vacuum.. Ideally, you would place your pump well below the bottom of your kettle and have the plumbing have no points that can form an air trap... (even a dip tube can hold air that causes pump problems, but the real culprit is usually a flexible line that goes up and down a little bit over other lines, cords, between brackets, etc... this is just a nightmare on the suction side of the pump) I have had good luck in having the plumbing go straight down, make a single U-band back up, and there is where I place the pump, with flow going vertically up, so if it gets an air bubble in it, it is very self-clearing... for the first year we used centrifugal pumps in homebrew, we cursed them... then we plumbed right, got our pump-chi, and have been going good for 10 years...