Temp Probe Location 3 Vessel E-HERMS

[Beer:30]

Having no luck with the search function. I know I've seen discussions on this before; thoughts on best temp probe locations for two temp probes in a 3 Vessel E-Herms? Running two Brew Commanders for control. Thanks!

 

[Ruint]

I have a 3 vessel herms system myself. I unfortunately have only 1 controller with the temperature probe on the output side of the coil from the hlt. I reasonably think that the other probes' best location would be on the mash tun itself, if I was to try to control another location.

 

[gavinr]

I have had a 3-vessel (15 gal) eHerms setup for 2 years, and have tried various positions for the probes, having finally settled on this:

Mash: Control probe directly in HLT, 7" from bottom; Monitor probe directly in MT, 6.5" from bottom. Additional monitor probe on HERMS return on outside of HLT. This extra probe gives me an immediate snapshot of the delta between the temp after the HERMS, and the temp in the MT.

Boil: Control probe directly in BK, 5" from bottom, Monitor probe directly on output of CF chiller.

I have found this to be the most temp-stable control configuration for my setup. The only potential downside, is that you have to be careful when stirring the mash or boil, so as to not whack the probes with your spoon. You can use a thermowell to protect the probe, but will have accuracy and speed issues. I'm careful while stirring, and use short probes in the kettle - have never had an issue. I also circulate the mash and HLT continuously with two pumps, and the probes are spot on because of no temp stratification.

I am not crazy about probes hanging off tees near output ball valves, and with my current setup, probes and cables are out of the way around the side and back of the kettles. Yes, you have to drill small ports on your kettle, but the weldless sensors from Auber are totally leak proof. Also, make sure to calibrate your controller/probes with a reliable instant-read thermometer.

 

[Bobby_M]

Agree. In HLT and in BK. You learn what the system offset is by probing the mash and comparing that temp to the HLT controller readout. Enter that offset in the controller settings. Now the actual mash should match the readout on the screen.

 

[LarMoeCur]

I run my HLT and MLT probes in Ts right off the valves. Like Ganinr hinted at they are protected in the T. I've had to replace my boil probe twice from being lazy and stirring with a mash paddle. Bent probes still work but it bothers my OCD. I also think you get a better temp reading from the bottom of the MLT. Wort coming out of the HERMS coil is sometines .5 degree hotter but never seems to make it into the grain bed. In the past I have ran my old thermometer in my MLT because I didn't trust the PIDs. The grain bed and my exit temps were virtually identical.

 

[mabrungard]

If there is a PID controlling an element, have the temp probe as close as possible downstream of that element.

 

[stevehaun]

I have the control thermocouple at the return to the top of the mash. I have a second monitoring thermocouple at the mash tun exit. At steady state, these two thermocouples either read the same temp or the control thermocouple reads 1C higher than the exit thermocouple.

 

[mabrungard]

Having the control thermocouple at the wort return to the tun is OK, but having it even closer to the heat source is better. The greater the distance, the more the PID algorithm is going to have to guess when heat is needed and it makes the system more dependent on having a decent flow rate. Sometimes the mash permeability won't allow a high flow rate. I find that the permeability of a mash is often significantly lower early in the mash and it becomes more permeable as the extract is pulled out of the grist.

I often see a larger difference in wort temperatures between the tun inlet and outlet locations when stepping the mash to another temp, but that's a temporary thing. 1C loss isn't too bad for a tun at steady state.

 

[LarMoeCur]

Having the control thermocouple at the wort return to the tun is OK, but having it even closer to the heat source is better. The greater the distance, the more the PID algorithm is going to have to guess when heat is needed and it makes the system more dependent on having a decent flow rate. Sometimes the mash permeability won't allow a high flow rate. I find that the permeability of a mash is often significantly lower early in the mash and it becomes more permeable as the extract is pulled out of the grist.

I often see a larger difference in wort temperatures between the tun inlet and outlet locations when stepping the mash to another temp, but that's a temporary thing. 1C loss isn't too bad for a tun at steady state.

The biggest problem is the kettle itself. If we could only put the probe in the center of the bottom. Why not add a bottom drain too. Now that would be awesome! It would be protected by the heating element and pretty darn close to the heat source. Someone needs to build kettle stilts like conical fermenters have!

 

[sicktght311]

My 3vessel system uses a temp probe in the outlet of the herms coil to control Mash Temp, and then a probe in the side of the boil kettle to control the boil.

The HLT is usually about 1.5-2degrees higher than the target mash temp.