Temperature control for beer kits

[Mash Monster]

I used to put the probe in a thermowell inside the fermenter. But since I started using a Keglands Rapt Pill I found that I get a more stable temperature by taping the inkbird probe to the outside of the fermenter.

Do you use an inkbird or rapt controller?

 

[Davegase]

Do you use an inkbird or rapt controller?

I use the inkbird to control temperature with the probe on the outside of the fermenter and the rapt pill (not the controller) to monitor temperature and gravity.
I ferment inside a converted freezer.

 

[Mash Monster]

I use the inkbird to control temperature with the probe on the outside of the fermenter and the rapt pill (not the controller) to monitor temperature and gravity.
I ferment inside a converted freezer.

The only reason I asked was that if you used the Rapt controller with the Rapt pill you wouldn’t need to use the probe and the pill would monitor the temperature.
I currently use either a Rapt controller or an inkbird with the probe inside the thermowell. The temperature is confirmed by my ispindel and it is usually within a couple of tenths of a degree.
I’ve tried both ways and personally Iget better control this way.
I suppose it depends on each individual set up so if it ain’t broke don’t fix it I suppose.

 

[GhostShip]

Do you folks with Inkbirds probe the air temperature or the beer temperature? I imagine in a small sealed chamber like a fridge the air will change temperature quite a lot faster than the beer (due to thermal mass as mentioned above). So with the probe in the air I expect the Inkbird will be switching on and off much more often than if it is in contact with the beer and possibly the beer temperature lags behind air temperature by an hour or more.

I have a ~20cm thermowell in the lid of one of my fermenters. It's okay for a cheapo thermometer I've got, but it's not a big enough bore for the Inkbird probe. Currently I don't have a fridge (as it rarely gets over 20C where I ferment and we're going into winter anyway), so taking air temperature is pretty useless - was planning to get another larger thermowell and use that, then add a cheap fridge to the setup at some stage.

As others have said, I tape the Inkbird probe to the side of the fermenter, covered with a patch of bubble wrap.

 

[norrie]

Ok quick update on this. I have now made several beers in my converted freezer with great success. I am no longer getting that tang in the beer. I've done ginger beer, Yorkshire bitter, lager and stout and also a winter ale. All have came out really well. I've got the temp set to heat at 18.5 and to cut out at 19. I just use a heat pad in the bottom of the freezer which is only 20 watts so very cheap to run.

 

[peterpiper]

Yeah I've seen that :) but what i mean is how quickly from the fridge compressor kicking in does it start to cool?

The big cooling lag would generally be, the time taken for a container of liquid to reach the surrounding air temperature, rather than time taken for air in fridge (or freezer) to reach the set temperature.
The former, will reduce, as the differential temperature increases (ie the colder the surroundings).

A flat bottom vessel, sitting on a cooling element would react the quickest. Fridges (& freezers) that circulate air, will cool the liquid quicker, than those that rely on convection (think wind chill factor).

As Antigozo pointed out, the temperature inside the fermenter goes up during active fermentation. This is because fermentation is exothermic, at that stage. And it's temperature can typically increase to 2 to 4°C above ambient.
A lower temperature setting might be recommended for the first few days, so that the exothermically increased temperature, doesn't exceed a good temperature for the yeast.

If say, the desired temperature is 20°C, the fridge is controlled to cool to 19C, and the heater to 21C. During vigorous fermentation, more heat is being generated, than would be removed at the 1°C difference (between set 19 and desired 20), so temperature will increase.
Having the temperature probe inside the fermenter, should give a big improvement on the above. Though I'm not sure, that I'd trust a regular inkbird probe to be waterproof.

But vertical position of probe, within the vessel, can still cause a fairly big difference, due to temperature stratification. As during less vigorous fermentation, the heated liquid from heater tube (usually towards top), being lighter stays around the top. While liquid, cooled by contact with the base and walls, being heavier sinks to the base.
I'd be interested, in seeing fridge stratification figures, if anyone's done any tests.

I don't have a fridge system. But using a heatpad, in a cold garage, and under lots of bubble wrap, the temperature (vessel exterior wall) can be over 6°C cooler towards top (of liquid). Despite the helpful convection currents, in this situation.