I'm not familiar with the project that inspired this one, but you should pay attention to hot spots, heat should be equally spread across the whole plate.
plus you should have good sensors and provide controllable configuration of heat points for soldering different components according to the manufacturer's datasheet.
@SiLeX So it may be due to an incorrect connection? Pins of module are untagged and I connected them according to the positions of schemes that I found online. All modules have same pinout?
@jvdk I agree with the point made by @evb , why would you want to wire connect the ultrasonic node rather than the usual radio connection ? You are adding levels of complexity and power demands for what reason ?
My ultrasonic water tank node (pro-mini+rfm69) is now 2 years on the same 2xAA batteries sending in levels every hour (RTC), the only problem encountered - condensation forming a drip on the face of the ultrasonic head during very low temperatures.