[MaxxxRacer]

the barb would be a few C cooler than the water i would think. the metal of the barb would disipate the heat faster than the water would so it would cool off. Feeling the brass barb on my rad right know I can confirm that it is noticably cooler than the water in the loop is..

Its best if you can get the probe to actually touch the water... but even then, the accuracty of the nurse is not.. well its just not accurate. A while back pH did some tests with the thermal probes compared to a calibrated high end measuring unit, and the temps varied from relatively accurate to 3-5C (if i recal correctly) off the mark... imo, i would call accurate within 1C of the actual temperature.. that being accurate only for the cheap probes that we purchase for computer related stuff.. the real probes are accurate within .1c...