Not enough hot water is normally the result of a heating element gone bad.
A lukewarm shower or a shower that goes from hot to cold very quickly is likely the result of a faulty hot water heater element. Replacing a hot water heater element is an inexpensive fix, compared with the cost of replacing the entire hot water heater. Once you've checked and identified the broken element, you can then decide whether to do the repair work yourself or not. Does this Spark an idea?
Instructions
1. Shut off power to the hot water heater. Locate the hot water heater's breaker at the circuit panel and flip it to the off position.
2. Locate the two access covers on the water heater. These will look like two small doors.
3. Remove the screws for the upper access cover with a screwdriver. Set aside the access cover and screws.
4. Remove the insulation covering the element. Be careful not to disrupt any of the wiring.
5. Pull off the plastic cover over the element. This should easily just pop off.
6. Disconnect one element wire from the upper heating element by unscrewing one screw and removing the wire.
7. Test the upper element with your multimeter. To do this, set your multimeter to RX1000. Touch one lead to the element bolt and the other lead to one of the screws. If your multimeter reads "infinity," your element is fine. If it reads "a closed circuit," then the upper element must be replaced. If you are unsure read your multimeter, please refer to the instructions that came with it.
8. Test the lower element the same way as the upper element.
Tags: water heater, your multimeter, upper element, access cover, heater element, heating element