I am using a USB-9211 to record 3 temperatures that are all connected to a waterbath that is set at 21C. The recorded temps vary over time more than a degree or 2 each way with no apparent pattern. There doesn't seem to be any reason for this. The water bath is calibrated and is accurate to +-.01C. I tried using an ice bath with the same results. Do you have any idea what could be causing this variation?
