After brewing outside during the winter months I came to the conclusion that there is a need to improve the Brewzilla 35L. The heat loss from the system is too high when using the naked kettle as it comes from the box. This is something I recommend everyone do even if you are using your system indoors.
Why you need to insulate the Brewzilla
One of the most important steps in the brewing process is the mashing step when you do an all-grain brew. The grains are hydrated and the temperature of the wort will activate the malt enzymes. The enzymes are responsible for the conversion of the grain starches into fermentable sugars. Different wort temperature will activate different enzymes resulting in more or less fermentable sugars. A rule of thumb is the higher temperature in the range of 60-70C the more non-fermentable sugars are produced and more body will be present in the finished beer.
When brewing my first NEIPA when I did a brew in -10C, the beer should have been mashed at 66C, it most likely was a 2-degree difference in the grain bill during the mash will give a totally different beer in the end.
Most all-grain systems have a recirculation of the wort during the mashing step to try and hold the temperature in the mash at a stable. Circulating wort from the bottom where the heating element and temperature probe is located to the top of the grain bill. The importance is to have the same temperature at the bottom of the kettle as the top and the middle of the mash.
Insulate the brewing kettle
Insulating the system will become even more important when brewing outside at colder temperatures. To improve the Brewzilla the first thing is to insulate the body of the brewing kettle, if you have a Brewzilla they have an insulation jacket that I use and recommend. If you want to DIY, buy a cheap foam sleeping mattress and cut it to fit your kettle. Hold it together with some duct tape and you will have the same function for just a couple of dollars.
Insulate the recirculation arm
To improve the Brewzilla even more from a thermal point of view the next step is to insulate the recirculation arm. During the mash, the wort will be circulating with a flow of around 1-2 liters/min. The metal construction of the recirculation arm will have a good heat dissipation to the environment resulting in a temperature drop of the wort being dispenced at the top.
The diameter of the tube is 1/2 inch, 12.7 mm, making a normal 1/2 inch tube insulation perfect for the task. If the insulation doesn’t have a slit to push the tube into, use a scissor to cut it open. If you decide to insulate the racking arm use tape to keep the insulation in place.
Improving the thermal effciancy of the Brewzilla
Doing these steps above will improve the Brewzilla from a thermal efficiency point of view. All types of all-in-one systems or brewing kettles benefit from this type of improvement. After insulating the kettle and recirculation arm the system will have a faster heat-up time and a higher boiloff. There will be a need to either reduce the amount of power during the boil or increase the pre-boil volume to compensate for the better efficiency of the system.
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