I just stumbled over the thing again today, so I did some search and came to nothing conclusive, thus I thought about asking here on Skeptics. But, first, I'd like to know if it is a question that can fit the rules.
Subject: Hot water boilers.
Half of the world claim that it's better to keep them always on. The other half, that it should be turned on and off following necessity.
Half of Internet agree with the second claim. The other half with the first.
I can't find any number, as simply as it should be taking a boiler and measuring its power consumption in both cases.
Can one of the two above claims be scientifically proved?