This is s post about brewing in the cold and the importance of knowing your equipment. I love my Brewzilla and it’s a step up from normal brew in a bag.
My last brew was a NEIPA, New England Pale Ale. On the brew day, the temperature was well below -10°C. Because of the boiloff, I always brew outside in my garden. The system a Brewzilla 35L (Link to Amazon) is equipped with a neoprene jacket. The neoprene jacket does help and I would say that anyone brewing outside even in normal weather should use one. The heat transfer to the environment, heat dissipation, from an uninsulated kettle will be high, a neoprene jacket or if you DIY with an old outdoor sleeping mat cut to fit with some duct-tape will make a huge difference.
During this brew, the mash temperature was set to 66C and everything was going fine. There was no problem holding the temperature according to the kettle built-in PID controller. During the boil, I had to use both the 2000W and 500W elements to get a nice rolling boil.
One week later, the beer was kegged and time for the first tasting. I’m pressure fermenting and force carbonating to the process can be quick. There was no body present in the beer to handle the massive IBU and hoppy flavour. Let’s see how this beer develops over time as it still is young.
After thinking for a while the most likely reason for this is the temperature drop in the recirculation loop caused a lower temperature in the mash. The element and sensor are located at the bottom of the kettle, see picture. The temperature of the worth is controlled at the bottom and then pumped to the top of the grain bill. The recirculation loop is an uninsulated stainless tube going on the outside of the kettle. the flow is around 2 liter/min. With some wind and displacement of the air around the tube, the heat dissipation will be massive, especially at -10°C. I should have known better because of my work with fluid dynamic systems.
How to improve the kettle to be brewing in the cold
Next time I brew my plan is to do a temperature profile of my kettle to understand the heat dissipation in the recirculation loop. Before that, I will insulate the recirculation tube with some standard tube insulation.
Have a homebrew!
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