In the above I cant work out why the solenoid ball valve hasn’t kicked in to allow flow of Glycol to keep the the temperature at 4.0C. Running a test with water in Chronical fermenter, in Beer Constant.
Any help greatly appreciated its hovering .5 above so I’ve obviously not set something.
Glycol supplied through converted maxi 310 cooler via python pump. Glycol recirculated through python loop to avoid pump stress when solenoid ball valves are closed.
Flow of Glycol to conical fermenters controlled via solenoid ball valves controlled via SSRs attached to spark via one wires, running latest brewblox release!
In your service page, could you please take a screenshot of your relations diagram (top right toggle), and export your blocks (top right action menu). That should clear up whether there are any unset links.
Ok so I think I may have found a potential contributor to the problem. See attached graph of cooling. This is just a test with me trying to get my head around the settings so excuse the mid flight changes.
I notice that the python pump on the Maxi 310 is not overly powerful, I think as a result of this, the length of my lines to the fermenter (appx 0.5-1m too the cooling coil and same on the route back), plus the volume of the cooling coil itself, means that with a minimum on time of 10secs there’s just not enough time for the freshly cooled Glycol to travel around the coil and provide sufficient cooling. As a result there is a lot of cycling of the solenoid valve to drop the temperature. I would estimate that I would need at least 20-30secs of on time for the Glycol to travel from the Maxi 310 along the cooling lines, through the coil and back again. Is this something I should look at increasing, my only concern here is around potential opposite effect of what I’m seeing overshoot v’s undershoot!
I can’t verify whether the used channels match the physical connectors, but the software configuration looks good: no broken links, disabled blocks, or any other obvious culprits.
Your reasoning is correct: if your glycol has a lot of travel time, then your system needs a longer minimum on constraint. The cool PWM period is now set at 10 minutes, but can easily be even longer.
For comparison: the default settings for a fridge include a period of 30 minutes, and a minimum on time of 3 minutes.
Increasing the minimum on / period has the potential to mess with the stability of your system, but first things first.
You can start with increasing the Minimum ON constraint until you clearly see your temperature responding whenever your actuator triggers.
Depending on what the result of that is, increase the PWM period to retain its period / minimum on time ratio.
If the temperature starts overshooting, increase the PID Td to compensate. If the error starts getting overly bouncy at that point, feel free to post some graphs of your PID history, and we’ll tweak some settings based on that.
Ok so looks like setting the minimum on time to 4 minutes seems to definitely show a temperature response although difficult to be truly accurate as at this temperature the SS Brewtech chronicals seem to suffer fairly badly from stratification due to very little mixing going on!
Could you expand a little on this point you made on how best to go about this
Depending on what the result of that is, increase the PWM period to retain its period / minimum on time ratio.
Yeah as I said I wonder if a big part of the problem is the stratification in so much as even though the time on period was short, in the initial period of crash cooling the graph above showing temperature drop relative to acutator state, the system did actually bring the temperature down. Little change was then observed once temperature reached around 5oc. That said however, when i then removed the fermenter lid and stirred to mix, it could be observed that the temperature reported by the probe then dropped to the actual set-point temperature, leading me to my conclusion that stratification was at play.
I suppose my question would be to you, is there anything that would concern you about the graph above tracking temperature relative to actuator state? does the temperature drop follow the pattern you’d expect over time? If not then perhaps the problem is with the stratification and therefore inaccuracy this brings to the reading at this crash cool lower temperature.
I’ve read other post on the forum suggesting that during normal fermentation control where thermal dynamics would be at play and therefore natural mixing that stratification and therefore innacurate reporting of temperature from the thermowell would not come in to play. I’m loath to make a change simply to cater for this crash cool scenario which may well cause issues with temperature control during active fermentation all be it its bit of a pain.
Honestly, I’m not qualified to offer an informed opinion on how the lower temperature will impact mixing.
The peaks between 1400 and 1500 in your graph are rather weird - I’m inclined to assume that’s you adding or replacing the measured liquid for testing purposes.
From 1500 onwards it’s consistent with glycol travelling slowly. Temperature consistently goes down while the system is more active.
Starting at 1830 the output drops, and then fails to be effective (temp creeps up). It looks like that is the moment you stirred the fermenter?
To isolate glycol travel time, maybe run some tests at a higher temperature (10-15C, depending on room temperature).
I heated the water to 18oc and then started a test cool cycle down to 15oc, left the 4 minute minimum on time?
Looks like the glycol had to be on for 1 minute before the temperature started to change, i stopped the cooling short before the cycle completed hence the sharp drop off.
Will do another test once i get it back up to 180c and try a crash down to 10oc and post back.
I’d put the value at 3 minute minimum on, and a 30 minute PWM cycle, but that’s more of a ballpark figure.
To test you could set up a Setpoint Profile that ramps up and down a few times, to see how well it tracks.
I think the best solution here would be to see if you can wrap some insulation around your glycol lines.
Otherwise the glycol will heat up in the lines before it reaches the conical if the pump speed is low.
In my home setup, I have a 10m period and a 10s minimum time. Keeping the conical at temp often requires less than 5% duty.
I’ve already got all of the glycol lines insulated with armaflex glycol line insulation.
Just running through a test at the moment and i can concur with your settings as it looks like with the longer on time and PWM cycle its overshooting the setpoint temperature.
I think the issue i was seeing was at the very low temperature and it looked like the glycol was not moving the temperature when in fact it was maintaning but not registering due to stratification.
I’ll post the graph once i have run through the profile test.
Thats the Brewey page i was on and its showing blank. I hit refresh in the browser after i did this and it showed that no layout selected message. I have a dashboard with a layout that i can edit in the builder but cant see it like i could before in the brewery area!
