Single Element Hot Water Heater

[tonitunes]

Hi there,
I have an approximately 7 year old single element hot water heater. Up until a couple of days ago it was just fine, water was hot. Then over night, the water became lukewarm, nothing was changed. I could understand if it were a dual element and one element went bad and the other was trying to heat the entire thing, but it is not.
Most of the troubleshooting I can find online refers to a dual element water heater so I'm not exactly sure where to proceed from here. Any advice/suggestions would be greatly appreciated.

[Dan O.]

water was hot. Then over night, the water became lukewarm

If it suddenly stopped heating it would take a while for the water too cool or be used up and replaced by cold. Are you certain it is still heating at all?

Dan O.

[tonitunes]

Yes, since then I've showered, used the water to do laundry and other things just as I normally would, and the water maintains this constant (much lower) temperature. I have already checked to make sure it has not been turned down and it has not.

[HayZee518]

have you tried to reset the thermostat? that's the red button on the controller. is your source voltage 240 or 120?

[tonitunes]

I pushed on the red button but it seemed like it was in as far as it would go, it didn't go in and like click or anything. Should I try pressing harder?
Also it's a 220 water heater.
Thanks!!

[HayZee518]

the reset is called a thermodisc. it should click when you reset it. if it doesn't replace it. shut off the power before you replace it. remove wires connected to it and it just moves upward out of a set of aluminum clips.