Prevent fermenter cooling overshoots by pulsing glycol chiller control#141

The digital temperature controller on the Grainfather conical fermenter switches on cooling when the fermenter hits the hysteresis limit for the target temperature and switches it off when the temperature sensor detects the temperature is back to the target value.

However, due to the fact that the cooling jacket it is high up in the fermenter and the temperature sensor is near the bottom, there is a time lag between the temperature drop at the cooling jacket and the the sensor detecting that the temperature has changed. In my observations, this lag is typically between 30 to 40 seconds.

As a result, this causes cooling overshoots - typically 0.8 to 1.0 degrees Celsius, which is a big drop if your yeast has a fermentation temperature range of only 4 degrees, for example.

Depending on ambient temperature, the hysteresis setting and how often cooling is initiated, this can generate a sub-optimal fermenter temperature cycle of short periods at target followed by sudden drops to below target followed by long periods recovering to target. Such periodic temperature shocks are not good for yeast and the result is an average fermentation temperature below target.

So, a long preamble about how cooling works, which I am sure the engineers at Grainfather are aware of. My suggestion:

It would be great if the digital controller for the conical fermenter were able to handle cooling lag by “pulsing” the cooling process. That is, by initiating cooling for a short period (e.g. 60 seconds) and then waiting the same period before testing the temperature. If the temperature is still too high, then another pulse can be sent to the cooler. This would then allow time for the temperature change to propagate to the sensor and would prevent cooling overshoots.

This could also be a selectable setting, so that it did not operate when trying to cold crash, etc.

I have been thinking about building such a controller and placing it in the control line between the glycol chiller and the fermenter, but would have thought the current controller could be reprogrammed to add this capability without too much difficulty. It already has the required timer, for example.

Alternativey, this function could be added to the glycol chiller itself.

Hi Anthony

many thanks for your very in-depth feedback. I have passed your suggestion on to our NPD department who will consider this for inclusion in our product development roadmap.

Many Thanks

Did anything ever come of this? I’m finding myself having a similar issue. I have the pump cooling kit set up with a glycol chiller I built myself and have set the temperature control on the chiller to -2.5C. Whenever the conical initiates a cooling cycle it overshoots by ~1C which causes the heating element to kick in. It seems rather wasteful and I’m wondering if there’s anything I can do on my end to minimize this overshooting.

Hello, I have the same issues with the cooling overshoot. This happens after a few days. I’m using the Conical Fermenter combined with the Glycol Chiller. All standard setup with the wifi controller which has de latest firmware (he says).

I’m experiencing a -1.5 c overshoot when cooling is initiated. So: target temp is 20c, hysteresis is 0.5, temp gets on 20.5 and the cooling is initiated (glycol at -4.5c). When 20c is reached, the glycol input stops and the controller goes back to ‘tracking’. But, the cooling does not stop and the temp keeps dropping very quickly, 0.1c per second all down to 18.5, eventhough the heating kicked in when temp reached 19.5c.

I’ve tried to set the glycol temp to -1.5c but this has no effect. What can I do? Room temp is now 20.6c. This was 21.5 last week. So maybe this has something to do with it. I now turned of cooling and enabled heating only, also because i have rais the temp according to fermentation schedule. Please help! The option that was suggested in the first post would be great. Please give us more options so we can tune the cooling process. Hope to hear from you soon

Hello, I also have the same issue and as far as I understand the temperature controller is a simple thermostat and not a PID controller. Thats the problem. Last summer I experienced the same problems with overshooting, then heating, overshooting again. I raised de GC4 glycol temp to +12 degrees Celsius. This helps a little but is not the solution. This set of fermenter and glycol chiller is sold as “professional fermentation control, just like the commercial breweries!” Well this part of it, is not. The option that Anthony Cook suggested is a solution that will do the job! Even with the simple thermostat function on the fermenter it is possible for Grainfather to implement this. I don’t know why this is still not taken care of 3 years later? Please Grainfather fix this!

I have the same issue. When using the default temperature settings (-4C) on the glycol chiller, the cooling cycle drastically overshoots my target temperature by up to 1.5C. I was achieving more stable fermentation temperature control using an old fridge and an ink bird, so I feel this is unacceptable for a $2,000 CAD pro-sumer system.

The only solution was to increase the glycol temperature to ~12C in order to maintain fermentation at 18C (+/- 0.3C). The problem is that now I can’t lager or cold crash while fermenting ale, so I have 3 unusable glycol ports.

Is this issue still on the product roadmap?

@James Varga I have not heard from Grainfather since I made my original post three years ago. This issue is unfortunately a major defect in this product and Bevie appears to have no interest or intention in remediating it. My feeling is that product innovation at Bevie ceased when the business that developed the original product range was sold to the Rahr group in 2018. We have seen bigger versions of the Grainfather and the conical fermenter, but nothing really new since then. I was disappointed to see that they did not even bother putting a cooling jacket layer into their new 70l fementer, for example, which is really lazy design and a big miss as far as leveraging the integration of their glycol chiller goes. I am thinking of scaling up to 70 litres but will not be using Grainfather products to do it. In the meantime, I will do what you do and set my glycol temperature to around 12 degrees C to prevent overshoot. As you note, this means I cannot lager or cold crash using the chiller, which was a key reason why I originally bought the product. For others who have posted here, I suggest you also look elsewhere for a solution.