If you look at it from a Bayesian point of view, you would say that the classical statistical tests are only valid when the prior, subjective probability of the tested hypothesis is around 1/2 or higher. If this hypothesis is very unlikely, you would probably not believe it, even if the data show a significant effect. On the other hand, if the hypothesis is very probable, you would believe it even after the data show no significant effect. Even while you cannot publish it, you would think that you had bad luck or that something went wrong with the experiment.

If I had time to tinker, I would consider to immerse the Pi in a jar filled with oil. The heat flows easily into the oil and especially if you expect only brief burst of intense heat generation, the large heat capacity of the oil would easily absorb these heat-waves. The advantage would be that the contraption is silent. The disadvantage of this solution might be that it would be easy to make a mess.

Is there a causal hypothesis about the adversarial health effects of increased levels of CO2? What causal, physiological, reasoning makes that people suspect slightly increased CO2 levels? The CO2 fraction in the lungs is under normal circumstances much higher than the elevated CO2 fractions that are discussed here (50,000 vs around 1000 ppm). In humans, under normal circumstances, the blood level of CO2 is the input of the physiological control system of ventilation and perfusion, so a slight increase of the CO2 fraction would at most cause an extra ventilation effort. On the other hand, increased CO2 levels in the air often go with poor ventilation and it can be imagined that the ventilation rates will have many confounding effects.

I think that when people say that a siphon works by gravity, they mean that gravity is the driving force that makes the water flow through the tube. You have shown that you need ambient pressure to make a siphon work, but that is similar as saying that you need a tube to make a siphon work. Saying that a siphon works by gravity and ambient pressure is equivalent to saying that a gas engine works by burning gas and sparks.

The plants that you burn in the machine pulled the carbon out of the air for you while they growed. Therefore the process is carbon-negative.