Mash Tun controlling HLT during mashing?

[-CHRIS-]

I built a electricbrewery clone out of keggles and ran my first all grain batch this weekend, a vanilla bourbon stout. I ended up with 74% mash efficiency which I was pretty pleased with my first batch.

I am using 3 x Mypin TD4 for control and monitoring. Of course, the MLT PID is only used for measuring temperature.

What I am wondering is should I switch control of the HLT heating element to the MLT controller to maintain temp during mashing? I am presuming I could have a problem with overshooting the MLT temp due to the thermal mass of the mash and delay in temperature change?

I think I could swap SSR control pretty easily.

Chris

 

[augiedoggy]

I built a electricbrewery clone out of keggles and ran my first all grain batch this weekend, a vanilla bourbon stout. I ended up with 74% mash efficiency which I was pretty pleased with my first batch.

I am using 3 x Mypin TD4 for control and monitoring. Of course, the MLT PID is only used for measuring temperature.

What I am wondering is should I switch control of the HLT heating element to the MLT controller to maintain temp during mashing? I am presuming I could have a problem with overshooting the MLT temp due to the thermal mass of the mash and delay in temperature change?

I think I could swap SSR control pretty easily.

Chris

why not just swap temp probe from the HLT to the MLT if you want to do it that way?

 

[JoshuaW]

You are correct, you will have overshooting problems. Say you mash in and your temp is 5* under. Your HLT element will now be firing the entire time, until you get your mash temp up. So if it takes 5 minutes to get your mash to temp, then now your HLT will be 5-10* over temp, which will gradually pull your mash temp up higher.

You want the quickest response time possible. That is why when we use RIMs tubes, we put the temp probe on the outlet of the tube, so that it is measuring the already heated wort and responding to that, not to the mass of wort that we are trying to heat up. Of course, the only real harm is that you might lose a batch, so if you want to try that, swap around some temp probes and let us know how it works! We only have these established methods because someone at some time tried it differently and decided that didnt work!

 

[-CHRIS-]

That is what I figured, I had flashbacks of my Signals and Systems class in engineering school. I did add 18 pounds of grain to 6.6 gallons of strike water, so it was a massive heat sink. I guess I should try increasing my strike water temp before making any other changes.

Chris

 

[orangehero]

The best two options are to use the temp of the wort returning from the heat exchanger to control the HLT or to use the temp of the water in the HLT and monitor the temp of the wort returning from the heat exchanger to determine the offset required. It's probably not necessary to monitor the grain bed temp assuming you're constantly recirculating.