Originally Posted by nickfogler
Just to follow up on this - I brewed today with my newly installed thermometer in my MLT. Lost 4-5 degrees in the MLT during a 75 minute mash. I'm starting to see the benefit of HERMS!
4-5*F seems excessive. If I avoid opening my cooler, I lose just a couple of degrees during a 60-70 minute mash.
Where is your thermometer installed in your TUN? I put a thermowell in mine so that I could monitor temps without opening the thing, but I made the mistake of installing the thing too high up the wall of the MLT. For a 5 gallon batch, my probe is monitoring the liquid above the grain bed rather than the temp if the grain bed directly. This results in my thermometer reading temps that are about 5*F lower than the actual mash temp.
If I shake the cooler up then the temp on the thermometer rises and gives me a better reading, but as the grain settles back down below the probe, the temp on the display starts to fall.
Dumb mistake on my part with the location of the probe. It does
read accurately on 10 gallon batches, though.