I begin preparing invert syrup in early August using the recipe and technology from the…

I begin preparing invert syrup in early August using the recipe and technology from the textbook "Beekeeping" by N.I. Krivtsov, V.I. Lebedev, and G.M. Tunikov (2000). My homemade thermostat is located under a shelter outside, where electricity is available. In August, nighttime temperatures can drop to 0°C, so to save energy and use a low-power heater, the thermostat walls are made from a low thermal conductivity material. I used M-35 foam, known for its high mechanical strength, making it both an insulator and a structural material. Using an electric saw with a sanding disc, I cut four sheets measuring 500x500 mm and two sheets of 500x400 mm, each 50 mm thick. I glued the thermostat body, which measures 500x400x400 mm internally, with PVA glue. The remaining two sheets of 500x500 mm serve as removable bottom and lid (see Fig. 1).