I've been wondering for a while, and not least now that I've found a post here about how to solve my calibration issues on the Sestos S1D PID, whether the ambient temperature surrounding the mashing container will effect the container in such a way that I may need to recalibrate depending on season?

I live in Iceland and I usually brew on my balconies. This means that I'll be brewing in temperatures ranging from -5°C to maybe +15°C. I have a 50 liter steel pot and a 5500 W element. I usually mash with around 35 liters in the pot, excluding grains.

To formulate my question specifically: Would a 20°C difference in ambient temperature significantly alter the mashing temperature or would the PID be able to keep it under control?

1 Answer 1


As far as the temp controller it doesn't care what the ambient temp is, unless the ambients exceed the tollerance of the controller IC it's self. Dry -5°c shouldn't be an issue with it working properly.

However, you have to consider the exposes areas of the pot are a huge heatsink. Insulate it the best you can.

Your biggest concern would be cold spots, mainly the edges and top. A recirculating mash or often stiring will help.

If left to only diffuse heat from the element, the mash in close proximity to the element may reach denaturing temps trying to heat to where the temp sensor is.

  • Thanks for that. My temp sensor is close to the element, so I figure that won't be a huge issue. Would you then agree that insulation and recirculation would be the steps to take to reduce the impact of ambient temperature fluctuations between seasons? I'm thinking something along the lines of blanketing the pot in reflectix and getting a proper pump to pump from bottom to top. Commented Feb 14, 2018 at 15:01
  • @ÞórgnýrThoroddsen whatever you can do to try and keep the temp even top to bottom, side to side. Insulating, mixing, recirc. May even need to insulate your lines and pump at those temps. Commented Feb 14, 2018 at 15:03

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