Storm Brewing wrote: ↑Thu Oct 07, 2021 4:37 pm
I have been reading up on Thermowells - can you recommend one?
Cheers!
I have found that thermowells don't actually work that well in a fermentation fridge because the probe is effectively immersed in a liquid that has a thermal capacity something like 20x that of air. This means that if, for example, your wort is 2C below the required temperature then the heating element will come on and stay on until the wort has reached the required temperature. However, the air surrounding the fermenter will heat up a 20x more quickly and can get very hot indeed if your heater is powerfull. The hot surrounding air continues to heat the wort even after the wort has reached required temperature and the heating has switched off, and you get over-shoot. Of course, your cooling (fridge) then kicks in, but now you get the opposite effect and the air in the fridge ends up too cold and you get overshoot in the opposite direction, which kicks in the heating again, and so on.... The end result is that you waste a lot of energy trying to control wild temperature swings in your fermentation fridge.
I tape a foam insulation pad to the outside of my fermenter and then slide the temperature probe between the pad and the fermenter. This way, the probe is primarily measuring the temperature of the wort through the wall of the fermenter, but is also getting enough feedback from the air, through the insulation pad, to cut off the heating/cooling if the air temperature become substantially different from that of the wort. The result is a much more constant temperature in both the air and the wort.
This is dependant on your setup though: if you have a fermenter with an insulated wall then it wouldn't work; nor would it be effective if you were heating/cooling the wort directly rather than the air around it.
A fine beer may be judged with only one sip, but it's better to be thoroughly sure.