Quote:
Originally Posted by tis
Sailin, is this a hobby for you?
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My hobby is saving money while staying safe and healthy. I consider all precautions and suggestions I receive, especially those that are based on evidence, experience, and logic.
Example: Health safety of using only the top element. You can only answer that by thinking about questions like: Does water in the lower, middle, and upper zones mix together? Or does hot water at the top remain at the top, while lukewarm water remains in the middle? If water in the top zone is heated to 140 degrees for 32 minutes, is a short shower drawn only from the top zone, where Legionella has been killed? Or is there a risk that lukewarm water from the middle zone will end up in the shower water? Is using only the top element any different from using the top and bottom elements with regard to bacteria? After all, even with two elements, there are still heat zones in the tank from cold to lukewarm to hot, so wouldn't that be equally dangerous? When you're taking a shower you can sense when the water is getting colder---is that dangerous?
Somewhere in a two-element tank there has to be water in the 68°–122° (some sources say 130°) zone where Legionella grows. I surmise that if the thermostat is set to 140, the water in the middle zone never makes it to the faucets because hot water rises to the top of the tank. There is no way to ensure that the entire tank is 140 degrees all the time, and it's not necessary that that occur. So the question becomes, is there enough HOT water at the top of the tank for low usage, such that one element would be sufficient to provide Legionella-free water? And if a person uses more water, will one element replenish the hot water fast enough for safety? My intuition says that one element would be enough for my low use, but I will try to confirm that before turning off the bottom element.
Some people have no patience with such questions and say, "Just turn the heater on 24/7 and get it over with." But inquisitive people have spent a lot of time investigating just such questions because health safety, fire safety, and conservation of water and power are important to them.
Not being curious is what led to Legionnaire's disease outbreaks in apartment buildings and homes. People just blindly accepted statements that water heaters should be set at 110 degrees to conserve power, or that 125 degrees kills Legionella bacteria. Even the government issued such statements. Science proved them to be false. Now it's hard to go back and change people's minds about what they heard for years. Is your water heater set to less than 140 degrees? Why? Is that based on facts, beliefs, or habits?