I received some parts for a new homebrewing system & thought I’d better calibrate the thermometers to ensure the desired mash conditions, where temperature is critical.
To start, I heated water to approximately mash temperature and put it in an insulated mug. I used a reference mercury thermometer and a Thermapen™ for reference, plus the thermometer being calibrated.
It’s difficult to see in the photo, but the mercury thermometer and the digital thermometer agreed to within about +/- one °F. The photo was taken after I adjusted the analog dial brewing thermometer (a Blichmann Brewmometer™), also to within about a degree. Let the zymurgy begin!