The article reminds me of a story from a friend that was an engineer at a major water heater company. Modern electric water heaters are already fairly efficient, but every model gets tested by the government to be given an efficiency rating.
The test consists of replacing the anode with a rod that has a series of temperature probes to measure the water at different levels in the water heater. Since water would form layers of different temperatures you needed measure at multiple locations to know the overall energy in the water. Then a series of water draws are performed with pauses between them and the total energy used is compared to the energy delivered.
Our engineer realized that if he could put the temperature layers at just the right locations then the calculations with the limited number of probes could be skewed. And this can be done by tweaking the height of the 2 heating elements. Just moving them a few inches.
The first time he tried this, an internal test came back at 101% efficiency. At little more tweaking and the test returns a consistent 99.x% that was respectable.
The test consists of replacing the anode with a rod that has a series of temperature probes to measure the water at different levels in the water heater. Since water would form layers of different temperatures you needed measure at multiple locations to know the overall energy in the water. Then a series of water draws are performed with pauses between them and the total energy used is compared to the energy delivered.
Our engineer realized that if he could put the temperature layers at just the right locations then the calculations with the limited number of probes could be skewed. And this can be done by tweaking the height of the 2 heating elements. Just moving them a few inches.
The first time he tried this, an internal test came back at 101% efficiency. At little more tweaking and the test returns a consistent 99.x% that was respectable.