Spark 3 temperature overshoots during mashing

So I have a different brewery layout to many on here & during my last two brew days the temperature overshot by 10C & the ony way I could get the temperature down again was by adding 10L cold water from the tap from my sparge water amount, I didnt realise until about 20 minutes that my temperature was too high, the beer tastes crap & had to be tipped so I’d like to get it fixed asap.

My set up is a HLT with a 3.6Kw heating element & a temp probe.

MT that recirculates through another small vessel with a 3kw heating element & coil inside, the MT & outlet of the small vessel both have temp probes.
BK with two 3.6Kw heating elements & a temp probe.

I run two Topsflo TD5 Brewblox CTL log 05.01.22.txt (284.5 KB)
24V PWM pumps.

Just to add to this I changed the following parameter after reading some posts from here:

Ti to 3m
Td to 1m

MT filled with water & temp set to 68C
Temperature when getting close to 68C was constantly dropping the power percentage in increments, temperature reached 70.3C & the percentage was at zero, the temperature is slowly dropping to its set point of 68C its currently at 69.8C but its taken 16minutes to drop this far, any pointers or do I just set mt desired temp to be 2.3C lower than I want?

Apart from settings, your log show quite a lot of events for temp sensors disconnecting/connecting. Is this manual, or indicative of hardware issues?

Hi Bob, I bought some temp probes from China & they often have me wondering if the temperature they are reporting is correct, so I take the temperature sensors from my cooling set up

It seems to happen every few seconds. The “New|TempSensorOneWire-1” seems to be the main offender, but I also saw two other addresses.

A downside of OneWire is that if a single device hangs, it brings down the others. This may cause issues for your DS2413.

For the settings side, could you please screenshot the heater PID graph?

It may be more informative to include the legend, and use the PID block graph. You can find it in the service page. In the actions menu is an option to show block values in a graph.

Do you use the HERMS setup generated by the wizard where the HLT setting is managed based on the mash setting? Your small vessel sounds similar to what the HLT is in that setup.

That prevents overshoot by not heating the HLT/vessel more than what will eventually transfer to the MT.

I’m sorry Bob I’m not sure how to do that on my iPad, do I have to log on using a laptop?

It should all be possible on an iPad, and if not, that’s something we should fix. What is the problem?

I had a brew day planned today & still the same constant temperature overshoots, ending up adding cold water to get the temp back down, then again back to within a degree of final temperature & we are still at 50% power, I resorted to controlling the power output using the maximum power constraints.

I think that the RIMS wizard is more compatible with my small HERMS coil & will test this set up, I will use this for when I’m mashing to see if I can stop the constant temperature overshoots.

I have added my log from the brew day, one thing to note is I have only two SSR’s connected at present & once I’ve completed the mashing & sparge, I disconnect the HLT & Hermit elements & swap over to the two elements for heating the BK, I change temp sensors in the HLT & MT to the BK temperature sensors.

Please share how you have set up your PIDs, sensor locations and volumes of the things that you heat.

Also share the internal graph of all PID blocks (click the PID and slide out the graph).

We don’t have enough information to help you.