HERMS Mash Temp Reading

[scruff311]

Hi,

I converted my old 15 gallon kettle to a mash tun and put in a thermowell to house the probe for my thermostat in my new HERMS system. The thermowell sits about 5" from the base of the mash tun which puts it at about the 4.5 gallon mark. On a typical batch, this is maybe 1" below the top of the mash. I've found that while the HERMS thermostat is reading a mash temp of say 150F, I am reading 145-146 at the bottom of the mash with my ChefAlarm thermometer. I can stir the mash and it will even out some, but once the pump kicks back on, the stratification will soon develop again. I don't want to have to keep stirring throughout the whole mash.

If I am targeting a mash of 150, should I be concerned that only the top of the mash is reading 150 with the bottom being 4-5 degrees less than that? Should I set the HERMS temp to be 152 so that maybe the middle of the mash is 150?

Thanks!

 

[Gnomebrewer]

There will always be temperature variation across the mash. The important thing is that you get to know your system. If you mash at 150, is the beer too thin? too much body? just right?
You might need to set the HERMS temp to 152, 154 or maybe 150 is just right. If it was me, I'd do the first batch at 152 and see how it goes - adjust for the next batch if necessary.
Also, insulating the mash tun might help to reduce the variation.

 

[gotraut]

For 1 bbl batches using eherms, I am 2-3 degrees hotter in the hlt compared to the mash tun thermowell. I have my pump valves fully open. It does take a bit for the temp to normalize - probably 15 minutes.