Temperature controle of HERMS


I am building a new HERMS setup and are planing to use BrewPi for temperature controol of the system.

Is it any best placment of temperature probes?




Place one in your herms tank for the buffer (as with the fridge in a fermenter setup), ideally away from the coil and element as they’ll be pulling the temp down/up respectively. I think the coil should be more stable so favour being near the coil and away from the element if you need to choose. I think the ideal would be in the centre of the ring of the herms coil, tbh, but there aren’t long enough wall-mounted sensors available for the BrewPi. I think one of the “waterproof” sensors in a conventional thermowell would have too much metal to get a responsive reading.

The equivalent of the fermenter in this setup is the mash tun. The temp will vary throughout your mash so try and pick somewhere representative & stable. So not near your inlet that’ll be affected by the heating element coming on/off & not tucked away in a corner where it might not see as much flow and might dissipate heat quicker through the walls. Of course, try and insulate your tun as well as possible to avoid temp variations. There’s also been talk about being able to average readings from multiple temp probes in Brewblox. I think in a mash tun having a sensor in the middle, one closer to the edge, and maybe a few others to average would be ideal as you can have large temp variations throughout a mash tun. Esp at micro-brewery scales.

While probes on the inlet/outlet of your coil might be interesting (you’d ideally want the temp at these points to be as close to each other as possible), I don’t think they’re of much use. The bulk of your wort is in your tun. Thats the thing you want to keep stable and that’s where the bulk of the conversion is going to be taking place.


I’m going to suggest an alternative approach here: place the probe near your HERMS coil exit.
That’s the temperature you will be most interested in, because that’s what the beer temp exiting the coil will be.

Here is how I placed it in my new setup. Herms exit at the bottom, because the water will be warmer there.



Thanks for the answers.

So a sensor setup like this would be good for regulation?

Hot Liquor Tank: one sensor sensing the hot water close to the outlet of the HERMS coil.

Mash Tun: one sensor in the "center" of the mash bed.

Boil Kettle: one sensor in the “center” of the worth volume.




I think that would work :slight_smile: