Water heater elements - top and bottom

[Stephen Tashiro]

Do the two heating elements in a typical hot water heater turn on and off independently? Or are they wired so that one (the bottom element?) won't turn on unless the other's thermostat has turned it on?

[Wayne Lovell]

The idea is that if you run completely out of hot water the top element will come on and heat approximately the upper third of the tank and then the lower element will come on and heat the rest of the tank. Like air the hot water will tend to rise to the top of the tank so you should set the lower element slightly cooler than the top so they don't both come on at the same time'

[Stephen Tashiro]

The idea is that if you run completely out of hot water the top element will come on and heat approximately the upper third of the tank and then the lower element will come on and heat the rest of the tank.'

Ok, but my question concerns whether the elements are wired so they work independently.

[Mike Cutler]

Technically, from a process control scheme, they do not work independently. It is a crude " and/or"
circuit as wired by the manufacturer.The upper element is the permissive for the lower element.
However, if you get a copy of your owners manual, it will detail how they work, and can be wired for different needs/ modes.
Look at the wiring and you'll see how they work together. There are many good web articles on how they work.

[Matt Marsh]

Only one element is powered at a time. The thermostat for the top element must have first reached it's set-point before it diverts power to the lower thermostat. The bottom element then maintains the entire tank of water to it's set-point, until the temperature at top thermostat falls below it's set-point.