A little electric water heater help please...

During the shoulder season I sometimes switch over to an electric water heater. Lately the wife has been complaining about lack of hot water, and when she went to fill the tub this morning there was some sediment in the water. I checked things out: I have 240 to the main thermoset control at the upper heating element. I have 240 to the upper element when the temp is below the set point and I can hear the water "popping" as the element heats up. The contact to the lower element shows 240 available to the lower thermostat if the upper is not calling for heat, but as soon as the upper kicks in this drops to 120 volts. I thought that both elements used 240.

Regardless I don't think the lower element is working because the lower half is always stone cold, so I'll replace that today.

So is the upper/lower set up normal? Is this something so that if one is running the other doesn't need as much?

Also which one do you set higher or do you set both the same?

Thanks

The lower element was indeed the culprit. I flushed the sediment out drained the tank (20 minutes) replaced the element (12 bucks and 5 minutes) and refilled the tank (10 minutes) and Bob's your uncle. The element had shorted out which is why I was seeing 110 volts when the upper was on. Now I get nothing until the upper shuts off.
The tank and timer were free 5 years ago on Craigslist so this is still a pretty good deal.

Thanks