where to read my mash temps on my new HERMS

[Boomvang]

I am building a flat HERMS system here at home. I am wondering on which end of the mash recirc should I put the thermocoupler that will control the heat under the HLT containing my heat exchanger? My thinking is that it would be best at the top of the recirc so that it is measuring the actual temp of the wort going back into the MT. Any thoughts?

[EagleDude]

That is exactly where I would put the thermocouple. If you end up placing is elsewhere, it won't really matter as long as you are consistent and adjust your brewing process accordingly (might have to set temps a degree or two higher/lower that a recipe calls for). Good luck with the new system build!

[CRBrewHound]

Neither!

If I am understanding you correctly you are wanting to measure the temperature of the wort going through for control of the HLT "water" heating. That is incorrect and will most likely give you issues with temperature overshoots and undershoots that decreases until balance is reached. You should instead measure and control the heat of the water in the HLT.

The liquid can never get higher then the temp of the heat transfer medium. so measure and control that. You should probably have a second temp gauge so that you can measure the temp of the mash and know the difference between the two so you can see when the mash temp has stabilized to that temp and "start the clock" on your mash.

[EagleDude]

Neither!

If I am understanding you correctly you are wanting to measure the temperature of the wort going through for control of the HLT "water" heating. That is incorrect and will most likely give you issues with temperature overshoots and undershoots that decreases until balance is reached. You should instead measure and control the heat of the water in the HLT.

The liquid can never get higher then the temp of the heat transfer medium. so measure and control that. You should probably have a second temp gauge so that you can measure the temp of the mash and know the difference between the two so you can see when the mash temp has stabilized to that temp and "start the clock" on your mash.

I have a non-automated HERMs system and I do it exactly as BrewHound describes. I know that my HLT needs to be ~6 degrees higher than my desired mash temp.

Also, upon thinking about this more ... measuring the output from the HERMS will fluctuate quickly with HLT temps, but not necessarily track quickly with actual Mash temp changes.

[Boomvang]

Neither!

If I am understanding you correctly you are wanting to measure the temperature of the wort going through for control of the HLT "water" heating. That is incorrect and will most likely give you issues with temperature overshoots and undershoots that decreases until balance is reached. You should instead measure and control the heat of the water in the HLT.

The liquid can never get higher then the temp of the heat transfer medium. so measure and control that. You should probably have a second temp gauge so that you can measure the temp of the mash and know the difference between the two so you can see when the mash temp has stabilized to that temp and "start the clock" on your mash.

I obviously need to work on my descriptive writing. I am looking to do exactly what you described above. I want the thermocouple to read the temp of the actual wort that will control the heat under the HLT. So you are saying to have a thermometer in the mash and have the PID control. That makes sense. It is just a matter of finding the water temp that gives me the correct mash temp. I am using an inline thermometer on the mash recirc. I can put it on the top side, or on the out at the ball valve coming from the MT. Which would give me the best idea of the actual temp in the tun? or should I just put a thermometer in the actual grain bed?

[codewritinfool]

No, he said measure the HLT temp and control THAT.

Additionally, measure the mash temp so YOU know when you've hit your temp so you can start your mash timer or whatever.

[Boomvang]

My writing is embarrassing. Esp when I am half drunk. Code, I got it. I guess what I am really wondering is, how big is the temp differential between the beginning and end of the recirc? Does it become homogeneous? or is there some temp lost through the lines and pump that is measurable?

[spiderwrangler]

My writing is often complete gibberish when I'm drunk. Normally if I screw up while typing, I backspace and make sure that I've written everything correctly. Drunk typing involves more misses, and often no correction.